zte umts ran equipment redundancy feature guide

RAN Equipment Redundancy WCDMA RAN

Feature Guide

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RAN Equipment Redundancy Feature Guide

ZTE Confidential Proprietary © 2010 ZTE Corporation. All rights reserved. I


Version Date Author Approved By Remarks

V4.5 2010-10-15 LouDeGang YuFeng Not open to the Third Party

© 2010 ZTE Corporation. All rights reserved.

ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.

Due to update and improvement of ZTE products and technologies, information in this document

is subjected to change without notice.


ZTE Confidential Proprietary © 2010 ZTE Corporation. All rights reserved. II

TABLE OF CONTENTS

1 Functional Attribute ............................................................................................ 1

2 Overview .............................................................................................................. 1

2.1 RAN Equipment Redundancy............................................................................... 1

3 Technical Description......................................................................................... 1

3.1 Board Redundancy Protection of RAN ................................................................. 2 3.1.1 Brief Introduction to Board Redundancy Protection ............................................. 2 3.1.2 General Process of Board Switching.................................................................... 3 3.1.3 Board Fault Detection ........................................................................................... 7 3.1.4 Redundancy Protection Solution for RNC Boards ............................................... 8 3.1.5 Redundancy Protection Solution for Node B Boards ......................................... 28 3.2 Port Redundancy Protection............................................................................... 31 3.2.1 Backup of Ethernet Port...................................................................................... 31 3.2.2 Backup of E1/T1 Port .......................................................................................... 33 3.2.3 Backup of SDH Port ............................................................................................ 33 3.2.4 Backup of Level-1 Switch Optical Port ............................................................... 33 3.3 Redundancy Protection of Communication Link ................................................ 36 3.3.1 ATM Link Backup ................................................................................................ 36 3.3.2 IP Link Backup .................................................................................................... 36 3.3.3 SCTP Link Backup .............................................................................................. 36 3.3.4 Data Division Transmission Backup ................................................................... 36

4 Parameter Description ..................................................................................... 36

4.1 Parameter List ..................................................................................................... 36 4.1.1 Configuration Information on Board Redundancy Protection ............................ 36 4.1.2 Configuration Information on Port Redundancy Protection ............................... 37 4.1.3 Configuration Information on Communication Link Redundancy Protection ..... 37 4.2 Parameter Configuration..................................................................................... 37 4.2.1 Configuration Information on Board Redundancy Protection ............................ 37 4.2.2 Configuration Information on Port Redundancy Protection ............................... 39 4.2.3 Configuration Information on Communication Link Redundancy Protection ..... 39

5 Counter and Alarm............................................................................................ 39

5.1 Counter List ......................................................................................................... 39 5.2 Alarm List ............................................................................................................ 39

6 Glossary ............................................................................................................. 42


ZTE Confidential Proprietary © 2010 ZTE Corporation. All rights reserved. III

FIGURES

Figure 3-1 Principle of Hybrid 1+1 Backup.............................................................................. 3

Figure 3-2 Active/Standby Switching Process......................................................................... 6

Figure 3-3 Active/Standby Interlock Circuit ............................................................................. 7

Figure 3-4 Connection of Major Boards in the RAN ................................................................ 9

Figure 3-5 Before Switching .................................................................................................. 10

Figure 3-6 After Switching of Optical Port ............................................................................. 11

Figure 3-7 After Switching Because of the Fault of Network Port of Internal Media Plane .. 11

Figure 3-8 After Switching Because the Active Board is Offline ........................................... 12

Figure 3-9 DTA Before Switching .......................................................................................... 12

Figure 3-10 DTA After Switching ........................................................................................... 13

Figure 3-11 DTA Hybrid 1+1 Backup Signal Flow................................................................. 13

Figure 3-12 DTI Before Switching ......................................................................................... 15

Figure 3-13 DTI After Switching............................................................................................. 16

Figure 3-14 DTA Hybrid 1+1 Backup Signal Flow................................................................. 16

Figure 3-15 Before GIPI4 Switching ...................................................................................... 17

Figure 3-16 Before EIPI Switching ........................................................................................ 18

Figure 3-17 SDTA2(1:1backup)before switching .................................................................. 23

Figure 3-18 SDTA2(1:1backup)After Switching of Optical Port Abnormal ........................... 23

Figure 3-19 SDTA2(1:1backup)After switchover caused by internal media plane Ethernet port fault .................................................................................................................................... 23

Figure 3-20 SDTA2(1+1 Backup) Before switching of Internal Media Plane Ethernet Port Failure ....................................................................................................................................... 24

Figure 3-21 SDTA2(1+1backup)After switching of Internal Media Plane Ethernet Port Failure ....................................................................................................................................... 24

Figure 3-22 SDTA2 After switching of active board off-line .................................................. 24

Figure 3-23 SDTI before switching of optical port ................................................................. 25

Figure 3-24 SDTI After switching of optical port.................................................................... 26

Figure 3-25 SDTI(Hybrid 1+1backup)Before switching of internal media plane Ethernet Port failure ........................................................................................................................................ 26

Figure 3-26 SDTI(Hybrid 1+1backup)After switching of Internal Media Plane Ethernet Port Failure ....................................................................................................................................... 26

Figure 3-27 After switching of active board is offline............................................................. 27

Figure 3-28 Typical Configuration of B8200 .......................................................................... 28


ZTE Confidential Proprietary © 2010 ZTE Corporation. All rights reserved. IV

Figure 3-29 FE Routing Interconnection Between UIM and UIM.......................................... 32

Figure 3-30 Trunk Interconnection of Control Plane ............................................................. 33

Figure 3-31 GUIM-GLI Connection........................................................................................ 35

Figure 3-32 Double-Shelf Interconnection Between GUIM Boards ...................................... 35

TABLES

Table 3-1 Backup Modes of RNC Boards ............................................................................... 8

Table 3-2 describes the backup mode of each board in the B8200. .................................... 28

Table 3-3 Backup Modes of B8200 Boards........................................................................... 28

Table 3-4 FE Routing Ports and Trunk Ports Supported by Various Boards ....................... 31

Table 3-5 GE Ports Supported by the GUIM/GLI .................................................................. 34


ZTE Confidential Proprietary © 2010 ZTE Corporation. All rights reserved. 1

1 Functional Attribute

System version: [RNC V3.09, Node B V4.09, OMMR V3.09, OMMB V4.09]

Attribute: [Optional]

Involved NEs:

UE Node B RNC MSCS MGW SGSN GGSN HLR

- √ √ - - - - -

Note:

*–-: The NE is not involved.

*: The NE is involved.

Dependency: [None]

Mutual-exclusion function: [None]

Remarks: [None].

2 Overview

2.1 RAN Equipment Redundancy

The 1+1 backup mode is configured for the key boards of the RNC and Node B, for

example, the system clock board, operation & maintenance board, and control plane

processing board. The load sharing backup mode (also called the resource redundancy

pool) is configured for the user plane processing board and various interface b oards.

Thanks to the redundancy configuration, the functions and performance of the whole

system are not affected in case one board is faulty. The interface board that processes

fiber transmission is configured with automatic protection switching (APS), th us ensuring

the reliability of high-speed lines, especially optical port transmission.

3 Technical Description

There are three types of redundancy protections in the RAN, that is, board redundancy

protection, port redundancy protection, and communication link redundancy protection.



3.1 Board Redundancy Protection of RAN

The RAN system provides diversified board backup modes, so as to ensure normal

system operation in case a board is faulty.

3.1.1 Brief Introduction to Board Redundancy Protection

In the RAN system, the board redundancy backup mode can be configured through the

BackUpMode parameter. The BackUpMode parameter can be configured to

BOARD_BACKUP_MODE_NONE (no backup) or the following values:

1+1 backup (BOARD_BACKUP_MODE_MASTERSLAVE)

For the mutual-backup boards, only one board carries services (including access

and processing) at a time and the standby board does not carry any service.

Hybrid 1+1 backup (BOARD_BACKUP_MODE_MASTERSLAVE)

Hybrid 1+1 backup is one type of 1+1 backup, which only has 1+1 backup at

processing boards but not interface boards.

1:1 backup (BOARD_BACKUP_MODE_1TO1)

Only one board processes data at a time. The interface units can be distributed in

the mutual-backup boards.

Load sharing (BOARD_BACKUP_MODE_MULTI_ONE)

All boards in the resource pool are active to share the load. In the redundancy

configuration mode, the system is not affected in case one board is faulty.

The comparison between the 1+1 mode and 1:1 mode is as follows:

Common feature

The two mutual-backup boards share one logical address (compared with physical

address, a logical address indicates a logical node for service. When function is

implemented, the active/standby board configuration is not concerned) and one

suite of bearer resources (for example, the circuit resource an d internal media

stream resource)

Difference

1+1 backup: Only one board is running in active status at a time.

1:1 backup: Resources and interfaces are divided into groups, and protection

switching is implemented in each group. The two mutual-backup boards work

cooperatively. The groups in a board can be in different working states. However,



make sure that if one group in a board is active, it must be standby in the other

board For example, in one board, Group A is active and Group B is standby. Then,

in the other board, Group A is standby and Group B is active. As a result, the two

boards may both have active resources at the same time and can process the

access service. For the SDTA2, SDTI and APBE boards, the corresponding optical

ports in the active board and standby board compose an APS group. The

active/standby state of a board is independent from the active/standby state of the

external optical port of the board.

Principle of Hybrid 1+1 backup:

As it is shown in 错误！未找到引用源。: The coming data stream A and B are

distributed into standby and active board respectively. Data stream A on standby

board will form as internal data stream after processing and connects to active

board through dedicated channel between active and standby board. Active board

will process the data stream from standby board and combines it with the data

stream B into new data stream C. Data stream C is a logical channel, the up level

processing only needs to process the data stream itself but not needs to know

the exact access point. Compare to the multi boards load sharing, hybrid 1+1

backup doesn’t need extra internal switching network.

Figure 3-1 Principle of Hybrid 1+1 Backup

Data stream

A

Data stream B

Access

Standby Board

Cross

board

Channe

l

Active Board

A,B combine into C by

load sharing

3.1.2 General Process of Board Switching

For the boards or devices in the 1+1 backup mode or 1:1 backup mode, the system not

only reports an alarm, but also takes preventive and self-healing measures (for example,

switching) in case a board is faulty. When the active board is faulty, the standby board



takes over its work, thus preventing the service functions from being affected for a long

time.

In addition, the system also provides some means to adjust the active board manually.

To verify whether the current standby board can work normally, manual switching can be

initiated to switch the standby board to the active state.

The RAN system provides the basic common switching reasons for the boards in 1+1

backup mode and in 1:1 backup mode. For different boards, the RAN provides different

switching reasons for different devices and functions on the boards. The following

section describes the general switching reasons and switching process.

3.1.2.1 Reason for Board Switching

The general switching reasons are as follows:

1 Man-machine Command

The system allows user to initiate a switching to the specified board from the OMC

by command.

2 Key-press switching

Each board supports the switching that is initiated through manual intervention from

a panel key-press. Press EXCH key in the panel of the active board, and then user

can initiate the active/standby switching.

3 Abnormal switching due to reset of active board

This is an abnormality processing flow after the active board is reset. If the active

board is reset due to manual intervention or its abnormal operation, the original

standby board automatically initiates the abnormal switching process, thus switches

itself into the active board. In this switching mode, the active board is suddenly

reset, so some service data cannot be synchronized to the standby board. After the

standby board takes over the work, some service data is lost.

4 Abnormality of network interface of the control plane

Boards work on the basis of messages of the control plane. When the network

interface of the control plane is abnormal, the normal operation of boards is surely

affected. If detecting that the network interface of the control plane does not receive

any packet, the system resets the board and thus attempts to restart the network

interface. Before the reset, the system instructs the standby board to initiate the

switching process through the primary channel so that the standby board can takes

over the ongoing services.

5 Removal of board

Each board is configured with an unplugging switch. Before a board is removed,

the system initiates the active/standby switching through an interrupt notice. The



standby board takes over the work first before the active board is out of position.

Meanwhile, the system reports the switch-on alarm and lights up. During the

switching, the ENUM indicator flashes quickly at a frequency of 5 Hz. Upon

completion of the switching, the ENUM indicator flashes at a frequency of 1 Hz.

Before the ENUM indicator flashes at a frequency of 1 Hz, do not remove the board.

Otherwise, the system triggers the abnormal switching process due to the reset of

the active board, as described in 3).

Besides the common reasons described above, other reasons, such as operation faults

of board, may trigger the active/standby switching.

3.1.2.2 Switching Priority Control

Board switching is intended to restore the system from the faulty state. If the standby

board has severer problem than the active board , the switching process is of no use. To

avoid this problem, user can configure the switching reason according to the fault

severity.

Except for the switching initiated by manual intervention, other types of switching are

initiated by the system automatically, that is, each switching reason corresponds to a

specific board fault. If detecting a fault in the acti ve board, the system initiates the

active/standby switching. If detecting a fault in the standby board, the system sets a fault

flag (hereinafter referred to as the switching barring reason). According to the severity of

faults, the system sets some levels for the switching reasons and switching barring

reasons. The higher the level is, the severe the fault is. When the active board initiates

the active/standby switching, the standby board compares the level of the switching

reason with the level of the switching barring reason. If the level of the switching reason

is higher, it indicates that the fault of the active board is severer and thus the system

allows the active/standby switching. Otherwise, the fault of the standby board is severer

and thus the system bars the active/standby switching.

To avoid frequent active/standby switching and switching -back, the system sets a low-

level 5-minute switching barring every time a switching process is complete.

3.1.2.3 Switching Flow

When both the active and standby boards work normally, every functional module in the

active board synchronizes the key information to the standby board at real time.

A normal switching process comprises three phases including preliminary switching,

standby-to-active (SA) switching, and active-to-standby AS) switching, thus switching the

board process and communication link, as shown in Figure 3-2.



Figure 3-2 Active/Standby Switching Process

Active board Standby board

Begin：

communication

link switch

SA

End：

communication

link switch

back

AS

Pre：

Sync data

Hardware

active/standby

switch

Starting switch

After receiving a switching request, a board first makes necessary judgment, for

example, whether the current board is an active board, and whether the standby board

is in position. If the switching conditions are met, the active board sends a preliminary

switching command. The standby board compares the level of the switching barring

reason with the level of the switching reason. If the level of the switching barring reason

is higher, the system bars the active/standby switching. Otherwise, the system

implements the preliminary switching operation, that is, instruct the active board and

standby board of the registered process to perform necessary active/standby data

synchronization. In this phase, the active board is always in active state and can

implement normal service functions. After the preliminary switching is complete, the

system implements the active/standby switching between the active process and

standby process. The active process and standby process are in different boards, so the

ongoing services are affected transiently. To minimize the impact, the system

implements link switching upon completion of the preliminary switching, that is, instruct

another service board to cache messages and send the cached messages to the new

active board upon completion of the active/standby switching.

In the SA(Slave to Active) phase and AS(Active to Slave) phase, the system instructs

the registered processes to implement the active/standby switching. The detailed

switching is implemented in each process respectively .

After the SA switching and AS switching are complete, the system switches to the

original link and sends the messages cached by another service board to the new active

board.



All normal active/standby switching processes follows the above flow. For the a bnormal

switching due to reset of the active board, the system cannot follow the above switching

flow because the active board is not in position. After receiving the interrupt message

because the active board is reset or out of position, the original stan dby board

immediately implements the SA switching and link switching and then takes over the

services of the original active board.

3.1.3 Board Fault Detection

The RAN provides diversified mechanisms for checking whether a board works normally.

The following section describes some fault detection mechanisms common to multiple

boards. In addition, different functional boards also provide other fault detection

mechanisms.

3.1.3.1 Partner Board In-Position Detection

Through an interlock circuit, the active and standby boards implement the active/standby

competition and check whether the partner board is in position. Figure 3-3 shows the

interlock circuit.

Figure 3-3 Active/Standby Interlock Circuit

单板 B 单板 A

O_MS-VIE O_MS-VIE

I_MS-VIE I_MS-VIE

MASCT MASCT

Board A Board B

MASCT (reverses the phase of output signals or MASCT inside the logic) is the

active/standby competition signal controlled by software, and is used for the

active/standby competition between boards. I_MS -VIE and O_MS-VIE are the interlock

signals between boards. If the actual level of MASCT is a high level, it indicates that the

board is competing for the active state. If the actual level of MASCT is a low level, it

indicates that the board does not compete for the active state. If the actual level of

O_MS-VIE (I_MS-VIE signal of the peer board) is a low level, it indicates that the board

is in active state. Otherwise, it indicates that the board is in standby state.

If the active board detects that the standby board is in position, the active board

synchronizes its data to the standby board through the primary channel. If the standby



board detects that the active board is offline, the standby board is switched to an active

board.

3.1.3.2 Communication Check for the Internal Media Plane

If a board (for example, APBE, RUIB, and EUIP) has the internal media plane

communication capability, the board can also provide a mechanism of checking the

communication in the internal media plane. Through this mechanism, a board can trigger

the active/standby switching if detecting the abnormal communication in its internal

media plane.

The port check mechanism in the internal media plane is as follows: The board regularly

sends a check packet to the switching board GUIM from the specified media plane port .

After receiving the check packet, the GUIM loops back the check packet. If the board

does not receive the looped check packet within a certain period, the board determines

that the communication of the media plane is abnormal.

After detecting the abnormal communication of the media plane, the active board

triggers the switching.

3.1.3.3 Internal HW Communication Detection

If a board (for example, the IMAB and EUIP) has the internal HW communication

capability, the board can also provide a mechanism of checking the internal HW

communication. The check mechanism is as follows: The board sends a check packet to

the switching board GUIM at Timeslot 0 of HW. The GUIM loops back Timeslot 0. The

board checks whether the received loop back data is consistent with the sent data. If not,

the board determines that the HW link is faulty.

The active board triggers the switching process after detecting the fault of the HW link.

3.1.4 Redundancy Protection Solution for RNC Boards

The table describes the backup mode of each board in the RNC.

Table 3-1 Backup Modes of RNC Boards

Functional Board

Backup Mode Remarks

APBE

1:1 backup

When the active board is switched to a standby board, the original active board is not reset.

The 1:1 backup mode must be configured if APS between boards is required.

Support the APS of two pairs of STM-1 interfaces in a board or one pair of STM-1 interfaces between boards.

DTA Hybrid 1+1 backup, 1:1 None



Functional Board

Backup Mode Remarks

backup

DTI Hybrid 1+1 backup, 1:1 backup

None

SDTA2 Hybrid 1+1 backup None

SDTI Hybrid 1+1 backup None

GIPI4 1+1, load sharing None

GLI Load sharing None

GUIM 1+1 backup None

ICM 1+1 backup None

THUB 1+1 backup None

PSN Load sharing None

PWRD No backup None

RCB 1+1 backup None

ROMB 1+1 backup None

RUB Load sharing None

SBCX 1+1 backup None

UIMC 1+1 backup None

Figure 3-4 shows the connections of the main boards in the table.

Figure 3-4 Connection of Major Boards in the RAN

Resource Shelf BGSN

GUIM

Control Shelf BCTC Switch Shelf BPSN

GUIM

PSN

GLI

APBE

CHUB

UIMC

RCB

ROMB

GIPI DTB RUB GIPI

GLI

UIMC

User Plane Control Plane

Iu/Iur/Iub Port

STM-1 E1 FE

OMC-B

FE

OMC-R

Circuit（HW）

ICMGPS

Antenna

GE

EIPIIMAB

RCB

Control Plane Data Stream

User Plane Data Stream

Circuit Data Stream Processing Unit

Switch Unit

Interface Unit



3.1.4.1 APBE Troubleshooting Process

The APBE provides four external STM-1 optical ports. The APBE boards support the 1:1

backup between boards. In this case, APS should be configured for the optical ports

between the APBE boards. When the inter-board APS is configured, 4 optical port APS

protection groups between boards are supported. The protection of optical ports of the

APBE boards complies with G.841[1], and supports the 1:1 bidirectional protection of

APS. For details on APS, refer to ZTE UMTS ATM Transmission Feature Guide.

The switching of the APBE boards can be triggered by the following reasons:

1 The active optical port is abnormal.

2 The communication to the internal media plane is abnormal.

3 The active board is offline.

Figure 3-5 shows the switching triggered by the fault of the active optical port. The

colored lines indicate the connection that data transits currently. The colored blocks

indicate the processing units that data transits currently. Before switching:

Figure 3-5 Before Switching

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

Active Board Standby Board

Workig Optical

Port

Protection Optical

Port

Inner Media Plane

Ethernet Port

Inner Media Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Inner Control Plane

Ethernet PortControl

Plane

Processing

Unit

Media

Plane

Processing

Unit

Through the APS mechanism for optical ports, the system initiates the switching after

detecting that the frame of the active optical port is lost. Meanwhile, the media plane

processing units of the faulty APBE are switched to the APBE where the protected

optical port is located. After switching:



Figure 3-6 After Switching of Optical Port

主板Active Board

Inner Media Plane

Ethernet Port

Inner Media Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Standby Board

Working

Optical Port

Protection Optical

Port

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

After the active board detects that the communication to the internal media plane is

abnormal (for details, see Section 3.1.3.2”Communication Check for the Internal Media

Plane”), the active board is switched over. After switching:

Figure 3-7 After Switching Because of the Fault of Network Port of Internal Media

Plane

Active Board

Inner Media Plane

Ethernet Port

Inner Media Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Standby Board

Workin Optical

Port

Protection Optical

Port

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

When the active board is reset or is removed, the standby board detects that the active

board is offline through the interlock circuit (for details, see Section 3.1.3.1”Partner

Board In-Position Detection”). Then, the standby board is switched to the active board,

and completely functions as the active board. After switching:



Figure 3-8 After Switching Because the Active Board is Offline

Active Board

Inner Media Plane

Ethernet Port

Inner Media Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Standby Board

Working

Optical Port

Protection Optical

PortMedia

Plane

Processing

Unit

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

Control

Plane

Processing

Unit

3.1.4.2 DTA Trouble shooting process

DTA board directly provides E1/T1 interfaces. It supports inter-boards 1:1 backup and

Hybrid 1+1backup.

The following reasons may cause faulty switch of DTA:

Communication to internal media plane is abnormal

Active board is offline

The switching process of DTA board is shown in the following figures. The lines in color

depict the active path where data is currently carried on. Whilst, the blocks in color

shows the active unit where data is currently processed. Before switching:

Figure 3-9 DTA Before Switching

Control

Plane

Processi

ng Unit

Media

Plane

Processi

ng Unit

Control

Plane

Processin

g Unit

Media

Plane

Processin

g Unit


Internal Media

Plane Ethernet

Port

Internal Media

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

DT

Access

DT

Access

Cross Board

HW

External

DT

access

Extern

al DT

access

After switching caused by any reasons:



Figure 3-10 DTA After Switching

Control

Plane

Processi

ng Unit

Media

Plane

Processi

ng Unit

Control

Plane

Processin

g Unit

Media

Plane

Processin

g Unit


Internal Media

Plane Ethernet

Port

Internal Media

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

DT

Access

DT

Access

Cross Board

HW

External

DT

access

Extern

al DT

access

When active board detecting abnormal communication of internal media plane, its will

initiate switching process. Detection mechanism refer to 3.1.3.2.

When detecting active board offline, standby board will switch over to active board and

take over all of active board’s function.

Principle of DTA hybrid 1+1 backup is shown below:

E1/T1 signal input through DTA interface is processed into internal HW and converged

into active board through TDM switching chip. TDM signal is send to IMA processing

chip which supports IMA group. EMA link messages from multiple E1 belong to one

logical path, IMA chip will make load sharing on active IMA links. At the back plane,

message of IMA group link connects to NP through SPI.

Figure 3-11 DTA Hybrid 1+1 Backup Signal Flow

TDM SwithAccess processing

Link

processing

Load sharing

processing

TDM SwitchAccess processing

Link

processing

Load sharing

processing

32 E1/T1

access

32 E1/T1

access

8*8MHW

8*8MHW

2×32MHW

m*n MHW

m*n MHW

Message

processing

Message

Processing

SPI

SPI

To

Internal

Switch

Network

To

Internal

Switch

Network

Totally there are 64 E1/T1 in the unit, the first 32 E1/T1 connect to the left board in order,

the second 32 E1/T1 connect to the right board in order. When configuring link

group(IMA link group, MP), equably distribute the PPP/IMA links to the right and left

board in order to get the best protection.



Physically the 2 *32 M HW is multiplied on one pair of LVDS (Low Voltage Differentiate

Signal). This LVDS only exists in BGSN frame, so this backup scheme can only be

applied to BGSN.

The connectivity logic of left and right board is same, but the connectivity result is

different due to different mapping relationships. For example: Suppose link group C is

composed of link group A and B, A is configured at No.1 E1 (first port of left board), B is

configured at No. 33 E1 (first port of right board). When left board is active, it connects

No.1 E1 to A, and the first E1 on right board will connect to B through HW. When right

board is active, it connects its No.1 E1 to B, and left board will connect its No.1 E1 to A

through HW.

3.1.4.3 THUB Troubleshooting Process

In the RAN system, the THUB is the center of data exchange between control planes in

different shelves. The THUB boards work in the 1+1 backup mode. The port of the

control plane undergoes high-resistance multiplexing. The communication of the control

plane is implemented through the active port of the active board. When a port of the

THUB is abnormal, the control plane communication is interrupted between the shelf

connected to this port and other shelves and thus the shelf cannot work normally. When

the THUB is abnormal, the control plane communication is interrupted among all shelves

and thus the system cannot work normally. To avoid the problem, the THUB boards

provide port redundancy backup and board redundancy backup. There are the following

backup scenarios:

1 The control plane communication between shelves is abnormal

In the TRUNK interconnection mode, the system checks the link of the control

plane according the hardware status of the control plane and packet

receiving/transmitting status. If detecting that one or more ports in a TRUNK gro up

in the active board are abnormal for at least one minute, the system switches over

the board, so as to ensure normal communication of the control plane.

2 GE port protection inside BCTC shelf

The THUB is interconnected to the UIMC in the same shelf through the GE port of

the backplane. If the link is interrupted, the control plane communication between

other shelves and the other service boards in this shelf is interrupted, thus causing

a great impact. The THUB checks the receiving/transmitting status of the packets

between the THUB and the GE port of the backplane of the UIMC. If detecting that

data receiving/transmitting is abnormal, the THUB performs board switching and

thus attempts to recover itself.

For further information on THUB backup, see Section 3.2.1.



3.1.4.4 DTI Troubleshooting Process

DTI board directly provides E1/T1 interfaces. It supports inter-boards 1:1 backup and

hybrid 1+1backup.

The following reasons may cause faulty switch of DTI:



The switching process of DTI board is shown in the following figures. The lines in color

depict the active path where data is currently carried on. Whilst, the blocks in color

shows the active unit where data is currently processed.

Before switching:

Figure 3-12 DTI Before Switching

Control

Plane

Processi

ng Unit

Media

Plane

Processi

ng Unit

Control

Plane

Processin

g Unit

Media

Plane

Processin

g Unit


Internal Media

Plane Ethernet

Port

Internal Media

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

DT

Access

DT

Access

Cross Board

HW

External

DT

access

Extern

al DT

access

After switching caused by any reasons:



Figure 3-13 DTI After Switching

Control

Plane

Processi

ng Unit

Media

Plane

Processi

ng Unit

Control

Plane

Processin

g Unit

Media

Plane

Processin

g Unit


Internal Media

Plane Ethernet

Port

Internal Media

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

DT

Access

DT

Access

Cross Board

HW

External

DT

access

Extern

al DT

access

When active board detecting abnormal communication of internal media plane, its will

initiate switching process. Detection mechanism refer to 3.1.3.2.

When detecting active board offline, standby board will switch over to active board and

take over all of active board’s function.

Principle of DTI hybrid 1+1 backup is shown below:

E1/T1 signal input through DTI interface is processed into internal HW and converged

into active board through TDM switching chip. TDM signal is send to NP (Network

Processing) after framing processing of HDLC. According to configuration, one MP (Multi

PPP) link may be formed by multiple PPP links. Under hybrid 1+1 backup, those PPP

will be distributed at active and standby board. NP only needs to process the MP links

and doesn’t need to care about the PPP itself which form the MP and where is the

bottom signal of the PPP.

Figure 3-14 DTA Hybrid 1+1 Backup Signal Flow

TDM SwithAccess processing

Link

processing

Load sharing

processing

TDM SwitchAccess processing

Link

processing

Load sharing

processing

32 E1/T1

access

32 E1/T1

access

8*8MHW

8*8MHW

2×32MHW

m*n MHW

m*n MHW

Message

processing

Message

Processing

SPI

SPI

To

Internal

Switch

Network

To

Internal

Switch

Network

Totally there are 64 E1/T1 in the unit, the first 32 E1/T1 connect to the left board in order,

the second 32 E1/T1 connect to the right board in order. When configuring link



group(IMA link group, MP), equably distribute the PPP/IMA links to the right and left

board in order to get the best protection.

Physically the 2 *32 M HW is multiplied on one pair of LVDS (Low Voltage Differentiate

Signal). This LVDS only exists in BGSN frame, so this backup scheme can only be

applied to BGSN.

The connectivity logic of left and right board is same, but the connectivity result is

different due to different mapping relationships. For example: Suppose link group C is

composed of link group A and B, A is configured at No.1 E1 (first port of left board), B is

configured at No. 33 E1 (first port of right board). When left board is active, it connects

No.1 E1 to A, and the first E1 on right board will connect to B through HW. When right

board is active, it connects its No.1 E1 to B, and left board will connect its No.1 E1 to A

through HW.

3.1.4.5 GIPI4 Troubleshooting Process

The GIPI4 provides an external 1000/100M GE port directly. The GIPI4 boards support

the 1+1 backup mode and load sharing mode.

The failures of the GIPI4 boards that may trigger switching are as followings:

1 The external Ethernet port is faulty.

2 Within 2 seconds, the external Ethernet port receives more than 128 bad frames.

3 The communication to the internal media plane is abnormal.

Figure 3-15 shows the GIPI4 switching process. The colored lines indicate the

connection that data transits currently. The colored blocks indicate the processing units

that data transits currently. Before switching:

Figure 3-15 Before GIPI4 Switching

Outer Ethernet

PortOuter Ethernet

Port

Control

Plane

Processing

Unit


Inner Media Plane

Ethernet Port

Inner Media Plane

Ethernet Port

Inner Control Plane


Plane

Processing

Unit

Inner Control Plane

Ethernet Port

Media

Plane

Processing

Unit

Media

Plane

Processing

Unit

Figure 3-16 shows the result after the switching triggered by any reason:



Figure 3-16 Before EIPI Switching

Outer Ethernet

PortOuter Ethernet

Port


Inner Media Plane

Ethernet Port

Inner Media Plane

Ethernet Port

Inner Control Plane

Ethernet Port

Inner Control Plane


Plane

Processing

Unit

Media

Plane

Processing

Unit

Control

Plane

Processing

Unit

Media

Plane

Processing

Unit

The external Ethernet faults are judged according to standard Ethernet circuit signals. In

case frames are lost, the system determines that the Ethernet is faulty and thus triggers

the switching process.

Bad frame detection is implemented according to the check result of the Ethernet frames

received by the bottom-layer chip. If more than 128 bad Ethernet frames are received

within 2 seconds, the system determines that the Ethernet works abnormally and thus

triggers the switching process.

After the active board detects that the communication of the internal media plane is

abnormal, the system initiates the switching. For details on the check mechanism, see

Section 3.1.3.2”Communication Check for the Internal Media Plane ”.

When the active board is reset or is removed, the standby board detects that the active

board is offline through the interlock circuit (for details, see Section 3.1.3.1”Partner

Board In-Position Detection"). Then, the standby board is switched to the active board,

and completely functions as the active board.

3.1.4.6 GLI Troubleshooting Process

The GLI is the exchange center of the media plane data between shelves. The board

backup mode is load sharing.

The GLI has four media-plane GE optical ports. In a Level-1 switching system, the

corresponding GE interfaces of the GLI work in the 1+1 backup mode. The

active/standby states of the GE interfaces are independent from each other. A whole

GLI has four independent active/standby GE modules. Two GLIs in the load sharing

mode may both have active GE modules. If one active GE module is abnormal, the

associated services are affected. If the whole GLI is abnormal, none of the GE modules

in the GLI can work normally, and the related services are interrupted. The redundancy

backup of the GLI and GE interfaces can prevent this problem effectively without

affecting the services. For details, see Section 3.2.4”Backup of Level-1 Switch Optical

Port”.



In addition, the GLI is interconnected to the PSN through the HSSL. The switching chip

in the FLI can identify the status of the HSSL. If the HSSL is interrupted, no packets are

sent from the HSSL to the PSN for switching.

3.1.4.7 GUIM Troubleshooting Process

The GUIM is the switching center for media plane communication, control plane

communication, and HW communication in the resource shelf (BGSN). During inter-shelf

communication, the GUIM has the routing function for the control plane and media plane.

The GUIM boards work in the 1+1 backup mode. The rear insertion card provides a pair

of external routing interfaces and one pair of TRUNK interfaces for interconnection of the

control plane. The panel provides two external GE interfaces. Like the THUB and GLI,

the system takes the redundancy backup measure without affecting the system when

the control plane link or media plane link in the GUIM is abnormal.

The GUIM is protected in following respects:

1 Redundancy protection for the control plane link, including board protection and port

protection. For details, see Section 3.1.2”General Process of Board Switching” and

Section 3.2.1”Backup of Ethernet Port”.

2 Media plane link protection: The media plane of the GUIM forwards the

active/standby state of the GE ports together with the active/standby state of boards.

The system checks a link by receiving and transmitting the link check packet. If

detecting that the link of the optical port in the active board is faulty, the system

switches over the optical module or the board. For details, see Section

3.2.4”Backup of Level-1 Switch Optical Port”.

3 For the network interface of the internal control plane, the system periodically

queries the receiving/transmitting statistics of the network interface of the control

plane. If detecting that the network interface of the control plane is abnormal, the

system switches over the board and thus the original standby board takes over the

work.

4 For the network interface of the internal media plane, the board in the shelf with the

media plane communication capability checks whether the link is normal through

packet interaction. If a faulty board cannot heal itself, the board with the media

plane communication capability sends a message to instruct the GUIM to switch

over the faulty board, thus removing the fault of the network interface in the active

GUIM.

5 The GUIM periodically checks the status of the HW communication links used in the

shelf. If all HW links are faulty, the system switches over the GUIM.

3.1.4.8 ICM Troubleshooting Process

The ICM provides the clock management and output function, and works in the 1+1

backup mode. In case a clock is faulty, the system has an extremely high requirement



for the recovery time. Therefore, the ICM is automatically switched over in hardware,

and software switching follows hardware switching. After software receives the interrupt

caused by hardware switching, the switching flow is the same as described in Section

3.1.2”General Process of Board Switching”. The ICM mainly provides the following

protection mechanisms:

The ICM checks the GPS module periodically. In case the active ICM is abnormal, the

system initiates the switching process. In case the standby ICM is abnormal, the system

sets switching barring.

The hardware in the ICM checks the status of the active and standby boards and

compares hardware signals. If the active board is abnormal but the standby board is

normal, the hardware automatically initiates hardware switching. After the hardware

switching is complete, the interrupt informs the software that the hardware switching is

complete. After receiving the interrupt, the software implements software switching, thus

keeping the active/standby consistency between the software and hardware.

The ICM supports the input of multiple clock benchmarks, thus providing redundancy

protection between clock benchmarks. The ICM checks the validity of each access clock

benchmark. If detecting that the clock benchmark is invalid, the ICM gives an alarm and

switches over the clock benchmark as configured.

3.1.4.9 PSN Troubleshooting Process

The PSN mainly exchanges the media stream data between the GLIs. The PSN boards

work in the load sharing mode. If two PSN boards are normal, the media streams are

shared by the two boards for forwarding. In case one PSN cannot work normally or the

HSSL is interrupted, the switching chip in the GLI automatically stops sending packets in

the HSSL. Instead, packets are sent only in a normal HSSL.

In case one PSN board is abnormal, the maximum switching capacity is halved. Based

on the current design, one PSN board is enough to satisfy the needs of service

switching.

3.1.4.10 RCB Troubleshooting Process

The RCB and ROMB are both a MP board. Except the functions and orientations, their

troubleshooting modes are similar to each other. The following section describes the

RCB troubleshooting process in detail.

The RCB is connected to the switching unit, and is responsible for protocol processing of

the control planes of Iu, Iub, and Iur. The active RCB is connected to the standby RCB

through a 100M Ethernet. The RCB boards work in the 1+1 backup mode.

The software running in the active RCB is the same as that running in the standby RCB

except for their working state (active or standby). During the initial power-on operation,



the two RCB boards compete for the working state. Hardware interlocking is configured

between the active RCB and standby RCB (for details, see Section 3.1.3.1”Partner

Board In-Position Detection"), thus avoiding the dual -active or dual-standby inclination.

After the active/standby competition is complete, the active and standby RCB boards are

up in different capacities respectively. The active RCB needs to read the configuration

data and receives the requests of other boards. The standby RCB actively interacts with

the active RCB, so as to ensure the consistency of software versions and static data. If

the data of the active RCB is changed during the normal operation, the system

synchronizes the changing data to the standby RCB through regular synchronization or

real-time synchronization. During the normal operation, the standby RCB receives the

synchronized data of the active RCB and keeps the consistency of static data between

the active RCB and active RCB, thus taking over the work of the active RCB smoothly in

real time.

In case the active RCB fails (for details on the reason, see Section 3.1.2.1”Reason for

Board Switching”), the standby RCB is automatically switched into an active RCB, its

logical address becomes the logical address of the active RCB, and the bottom -layer

communication link is also switched, thus ensuring normal communication between the

new active RCB and other boards. The original active RCB is automatically reset. After

the rest, the original active RCB becomes a standby RCB.

3.1.4.11 ROMB Troubleshooting Process

The ROMB processes a global process, controls the operation and maintenance of the

entire system (including the operation and maintenance proxy), connects itself to the

OMC through a 100M Ethernet, and isolates the internal network segments from the

external network segments. The ROMB also serves as the core of operation and

maintenance of the ZXWR RNC. It monitors and manages the boards in the system

directly or indirectly. The ROMB boards work in the 1+1 backup mode.

The ROMB troubleshooting process is similar to the RCB troubleshooting process.

3.1.4.12 RUB Troubleshooting Process

The backup mode of the RUB boards is load sharing, or called the resource redundancy

pool.

The RNC can be configured with multiple resource shelves, each resource shelf is

configured with multiple RUB boards, and each RUB board is configured with one CPU

and 14 (VTCD board) OR 15 (VTCD_2) DSPs. For RUB troubleshooting, the minimum

resource unit is a DSP.

When configuring a RCP module (the RcpModule parameter) through the OMC, you

need to configure the subsystem number (the SubSystem parameter) corresponding to

the preferred shelf for the RCP module. To obtain the RUB resources for new service

setup in the RCP, the RUB boards in the preferred resource shelf are polled. If a RUB



board is available, the RUB board is selected for service setup. Otherwise, a RUB board

is selected from another alternative shelf.

After the RCP selects a RUB board, a DSP will be selected in the RUB according to a

certain strategy. After the DSP is selected, the RUB board notifies the DSP number to

the RCP.

When a DSP in a RUB board is faulty, the status of the DSP is Unavailable. After

receiving the Unavailable notice, the RCP releases the DSP-related service, thus

avoiding resource deadlock. When a subsequent service is set up, the faulty DSP in the

RUB board is not selected for service setup until the DSP becomes normal again. If all

DSPs in the RUB board are faulty or the CPU of the RUB board is faulty, the RCP does

not select the RUB board for setting up a new service.

3.1.4.13 SDTA2 Troubleshooting Process

SDTA2 provides 4 CSTM-1 optical ports, and supports 246 E1 (each optical port support

maximum 63 E1) and maximum 168 IMA groups.

SDTA2 supports inter-board 1:1 backup and hybrid 1+1 backup, and 4 groups of inter

board optical ports APS protection are supported in this case. APS supports the

following protection types: 1+1 uni-direction, 1+1 bi-direction, 1:1 uni-direction and 1:1

bi-direction. All E1s accessed to the active optical port of backup board are transferred

to active board for processing (IMA links are also processed on active board). In case of

hybrid 1+1 backup, there is no backup on optical ports, all E1’s access to standby board

are transferred to active board for processing.

SDTA2 faulty switching includes the following reasons:

Active optical port is abnormal



The switching process of SDTA2 board is shown in the following figures. The lines in

color depict the active path where data is currently carried on. Whilst, the blocks in color

shows the active unit where data is currently processed.

For 1:1 backup, diagram of before switching is shown below:



Figure 3-17 SDTA2(1:1backup)before switching

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Active board Standby Board

Internal Media Plane

Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port

Working PortProtection Port

For 1:1 board backup mode, when detecting active optical port abnormal, active board

switching over will be triggered. Status after switching over is shown below:

Figure 3-18 SDTA2(1:1backup)After Switching of Optical Port Abnormal

Control

Plane

Processin

g unit

Media

Plane

Processin

g unit

Control

Plane

Processin

g unit

Media

Plane

Processin

g unit


Internal Media

Plane Ethernet

Port

Internal Media

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Working PortProtection

Port

Main Data

Path

In this case, when SDTA detecting abnormal communication to internal media plane, it

will trigger switchover. Diagram after switchover is shown below:

Figure 3-19 SDTA2(1:1backup)After switchover caused by internal media plane Ethernet port fault

Media

Plane

Processing

Unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit


Working portProtection Port

Internal Media plane

Ethernet PortInternal Media plane

Ethernet Port

Internal control

plane Ethernet portInternal control

Plane Ethernet port

Path for active and

standby data

Control

Plane

Processing

unit

For 1+1 hybrid backup, before switching is shown below:



Figure 3-20 SDTA2(1+1 Backup) Before switching of Internal Media Plane Ethernet Port Failure

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit



Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port

Working PortWorking Port

Active-standby Data Channel

For 1+1 hybrid backup, when active board detecting internal media plane

communication abnormal (refer to 3.1.3.2), switching will be triggered. After switching

status is shown below:

Figure 3-21 SDTA2(1+1backup)After switching of Internal Media Plane Ethernet Port Failure

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit



Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port



When active board resets or it is removed, standby board will detect active board off-

line(refer to 3.1.3.1) through inter-lock circuit and switch to active board to take over all

active board’s function.

Figure 3-22 SDTA2 After switching of active board off-line

Media

Plane

Processing

Unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit


Working portWorking Port

Internal Media plane

Ethernet PortInternal Media plane

Ethernet Port

Internal control

plane Ethernet portInternal control

Plane Ethernet port

Control

Plane

Processing

unit



3.1.4.14 SDTI Troubleshooting Process

SDTI provides 2 groups of CSTM-1 optical ports, and each group has two optical

ports(W,P).

SDTI supports inter-board 1:1 backup and hybrid 1+1 backup, and media plane and

control plane units switch separately. APS protection configuration is independent from

board configuration, it maximum 2 groups of inter board APS. APS supports the

following protection types: 1+1 uni-direction, 1+1 bi-direction, 1:1 uni-direction and 1:1

bi-direction. The switching of two groups APS is separated. The reason for optical switch

includes: LOS, LOF, SF, SD.

SDTI faulty switching includes the following reasons:

Active board is offline or reset.

APS switching includes the following reasons:

LOS, LOF, SF, SD on optical ports.

The switching process of SDTI board caused by the first optical port is shown in the

following figures. The lines in color depict the active path where data is currently carried

on. Whilst, the blocks in color shows the active unit where data is currently processed.

Before switching:

Figure 3-23 SDTI before switching of optical port

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit



Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port

Working PortProtection Port

When detecting frame loss on optical port through APS protection mechanism, it will

initiate optical port switching and all media plane processing units will switch to standby

board. After switching:



Figure 3-24 SDTI After switching of optical port

Control

Plane

Processin

g unit

Media

Plane

Processin

g unit

Control

Plane

Processin

g unit

Media

Plane

Processin

g unit


Internal Media

Plane Ethernet

Port

Internal Media

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Internal Control

Plane Ethernet

Port

Working PortProtection

Port

Main Data

Path

In case of hybrid 1+1 backup, before switching:

Figure 3-25 SDTI(Hybrid 1+1backup)Before switching of internal media plane Ethernet Port failure

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit



Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port



For 1+1 hybrid backup, when active board detecting internal media plane

communication abnormal (refer to 3.1.3.2), switching will be triggered. After switching

status is shown below:

Figure 3-26 SDTI(Hybrid 1+1backup)After switching of Internal Media Plane Ethernet Port Failure

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit



Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port





When active board resets or it is removed, standby board will detect active board off-

line(refer to 3.1.3.1) through inter-lock circuit and switch to active board to take over all

active board’s function. Status after switching is showing below:

Figure 3-27 After switching of active board is offline

Control

Plane

Processing

unit

Media

Plane

Processing

unit

Control

Plane

Processing

unit

Media

Plane

Processing

unit



Ethernet Port


Ethernet Port

Internal Control

Plane Ethernet Port

Internal Control

Plane Ethernet Port



3.1.4.15 UIMC Troubleshooting Process

The UIMC board is the switching board of the control plane communicatio n in the control

shelf (BCTC) and switching shelf (BPSN). The UIMC provides the shelf interconnection

interfaces (including the FE routing interface and trunk interface) through a rear insertion

card, and provides the control plane network interface internally.

The UIMC boards are under the redundancy protection in the following respects:

1 Redundancy protection for the control plane link between shelves, including board

protection and port protection.

2 For the network interface of the internal control plane, the system periodically

queries the receiving/transmitting statistics of the network interface of the control

plane. If detecting that the network interface of the control plane is abnormal, the

system switches over the board and thus the original standby board takes over the

work.

For details, see Section 3.1.2”General Process of Board Switching ” and Section

3.2.1”Backup of Ethernet Port”.

3.1.4.16 SBCX Troubleshooting Process

When acting as OMM server, SBCX managers all the NE of RNC and adopts 1+1

backup to avoid OMM service single point failure.

The reason of SBCX failure switching is shown below:

Active SBCX is off-line



Active SBCX abandons active status

The rear insertion board of SBCX is off-line

Active OMM software is fault

Active and standby SBCX have the same software running on them, including OmmHost,

OMMservice and Oracle database software. Two SBCX boards will compete for active

and standby during starting up. There is a hardware inter -lock mechanism(refer to

3.1.3.1) which will prevent system from double active or double standby. After the active

and standby competitive status end up, active board and standby boards work in its

status respectively. Only the OMM server software starting up with active status will work

and manage RNC, OMM in standby board only runs active -standby process to ensure

real-time data synchronization between active and standby boards.

When active board is faulty, standby board will automatically switch to active status.

Original communication links between former active OMM and RNC as well as MINOS

will automatically switch to new active board. Former active board will start up into

standby status.

3.1.5 Redundancy Protection Solution for Node B Boards

Figure 3-28 Typical Configuration of B8200

Table 3-2 describes the backup mode of each board in the B8200.

Table 3-2 Backup Modes of B8200 Boards

Functional Board Backup Mode Remarks

CC 1+1 backup

FS None

PM 1+1 backup

SA None

BPC Resource pool

PM

SA

CC

FS

FAM



3.1.5.1 CC Troubleshooting Process

Primary control

The active and standby CC boards work in the 1+1 backup mode. The active and

standby CC boards have completely the same hardware, run the same software,

and implement NBAP processing and the processing of the IP/ATM protocol stack

between the control plane and user plane. At a time, only one CC board is active.

The active CC board carries services, including access and processing. The

standby CC board does not carry any service, but receives the synchr onized data

of the active CC board and keeps the same running conditions as the active CC

board.

There exists an independent communication channel between the active CC board

and standby CC board. The active and standby CC boards run the same software,

but are in different modes. During the initial power-on operation, the two CC boards

compete for the active/standby state. Upon completion of the competition, the

standby CC board actively interacts with the active CC board, so as to ensure the

consistency of software versions and static data. During the normal operation, the

active CC board synchronizes the changing data (for example, database data,

control information of the control plane and user plane of the current access,

software parameters, and software versions) to the standby CC board through

regular synchronization or real-time synchronization. During the normal operation,

the standby CC board receives the synchronized data of the active CC board and

keeps the consistency of static data between the active CC board and active CC

board, thus taking over the work of the active CC board smoothly in real time.

The system can initiate the active/standby switching in the OMC. Alternatively, the

active/standby switching is triggered by a severe fault of the active CC board. In

this case, the current active CC board switches the current hardware and software

to the standby state, and only processes the synchronized data of the new active

CC board without processing any service. The original standby CC board swi tches

its software and hardware to the active state and takes over the work of the original

active CC board by using the synchronized static data and real-time operation data,

thus minimizing the impact of the fault of the original CC board on the entire system.

Clock

In case the active CC board is faulty, the active CC board is automatically to the

standby CC board.

Clock extraction redundancy design for multiple E1/T1 links: In case an E1/T1 link

is faulty, the system can automatically switch the faulty E1/T1 link to another

normal one for clock extraction.

Configuration of multiple clock reference sources: In case the current clock

reference source is faulty, the current clock reference source is automatically

switched to the standby clock reference source.



Clock holdover: When all clock reference sources are faulty, the system can keep

working normally for at least 90 days. (the BB8200 can be held over for at least 180

days)

3.1.5.2 PM Troubleshooting Process

The PM troubleshooting process is divided into two parts:

1 Active/standby switching mechanism of the PM board itself (including the PM

hardware/software processing)

2 Processing in the CC board

Active/standby switching of the PM board itself

The PM boards work in the active/standby mode. Both PM boards have an voltage

over a channel (in the 8200 device, every slot has a separate power supply channel)

to be powered. In terms of final selection, the hardware mechanism ensures that

the voltage of only one PM board acts on a specific power supply channel. In case

of the active/standby PM switching, switching is implemented immediately, thus

avoiding power-off of the boards.

Processing in the CC board

In the CC, the active/standby PM backup mode has three actions:

When the active PM board detects that a new board is inserted to a specific

slot, the active PM board immediately sends a message to the CC board. If

the CC board decides to supply power for the newly inserted board, the CC

board sends a power supply command to both the active and standby PM

boards, thus ensuring that both PM boards enable the output of the

corresponding channel.

The CC board sends the active/standby state reported by a PM board to the

OMC in real time, so that the OMC can display the active/standby state of

each PM board correctly.

The CC board periodically checks whether each PM board enables each

power supply channel, and synchronizes the result returned by the active PM

board to the standby PM board, thus ensuring that the active power supply

and standby power supply in the same power supply state.

3.1.5.3 BPC Troubleshooting Process

The cells set up in a baseband pool share all the baseband resources in the baseband

pool.



In case a baseband board is faulty, Node B assigns the cell setup and radio link setup

initiated by the RNC to another available baseband board in the baseband pool.

For the existing UEs in the faulty baseband board, Node B sends a reset request to the

RNC, requesting the RNC to reset the UEs in the faulty baseband board. The public

resources (for example, cells) in the faulty baseband board are deleted, and Node B

notifies the deletion result to the RNC through an audit response. The RNC initiates cell

setup and radio link setup again, and Node B assigns them to another available

baseband board in the baseband pool.

3.2 Port Redundancy Protection

3.2.1 Backup of Ethernet Port

Ethernet port backup mainly refers to the backup of the Ethernet ports between the

interconnected shelves. The shelves are interconnected to each other by different

means, mainly routing interconnection and TRUNK interconnection.

1 Routing interconnection: A pair of networks cables is used in two ends respectively.

At every end, one network cable is active and the other network cable is standby. In

case a working port is faulty, the faulty port is switched to another port for

continuous communication.

2 TRUNK interconnection: Through LACP protocol defined in IEEE802.3, the four

physical ports of the same attributes are aggregated, thus increasing bandwidth and

redundancy.

Port backup is also accompanied by board backup. The board backup mode is 1+1

backup. At a time, the Ethernet port in the active board receives and transmits data. In

case the port of the active board is faulty, the active/standby switching is triggered. The

Ethernet port of the new active board is active for transmitting and receiving data.

Table 3-3lists the FE routing ports and trunk ports supported by various boards.

Table 3-3 FE Routing Ports and Trunk Ports Supported by Various Boards

Board Routing Port (two FE ports in each pair)

Trunk Port (four FE ports in each group)

UIMC In the BCTC shelf and BPSN: 3 In the BCTC shelf: 1

GUIM 1 1

THUB 1

In a minor environment, the FE routing interconnection between UIM (including UIMC

and GUIM) boards can be used for networking. In a major environment, a THUB board

needs to be interconnected to other shelves for networking. In 0, a pair of routing ports

or a group of trunk ports can be interconnected between two shelves.



3.2.1.1 Routing Interconnection

Routing interconnection is also called FE interconnection. The UIM (including UIMC and

GUIM) board and UIM/THUB board can each provide one pair of FE ports for

interconnection. The boards work in the 1+1 backup mode. The Ethernet between the

active board and standby board communicates with the external world through high

resistance. 0 shows the connection mode. The blue channels indicate the available

communication links, and the read channels indicate the high-resistance channels. The

two available communication links include an active link and a standby link. All control

plane communication streams are in the active link. When the active link is faulty, the

system switches the faulty link to the standby link. In this communication mode, the

traffic is only 100M because only one channel is really used.

Figure 3-29 FE Routing Interconnection Between UIM and UIM

Active

UIM UIM

Active

Standby Standby

3.2.1.2 TRUNK Interconnection

The routing scheme only supports the t raffic of 100M, and cannot satisfy the needs of

high traffic. Therefore, the inter-shelf cascaded boards are interconnected through a

trunk, so as to increase the inter-shelf cascading traffic (theoretically, the maximum

traffic is as high as 400M). Trunk interconnection complies with the link aggregation

protocol. The physical links with the same transmission media type and transmission

rate are bundled together. Logically, these bundled physical links appear to be one link.

Link aggregation is also called t runking, which allows the peer physical link between

switches or between a switch and a server to multiply its bandwidth. Therefore, trunking

is an important technology whereby to increase the link bandwidth and ensure the

flexibility and redundancy of link transmission.

0 shows the connection mode. The blue channels indicate the available communication

links, and the red channels indicate the high-resistance channels. The four available

communication links are aggregated into a group of trunk ports. In case one link is faulty,

communication is implemented through another link.



Figure 3-30 Trunk Interconnection of Control Plane

Standby

Active

Standby

Active

UIM/THUB UIM/THUB

3.2.2 Backup of E1/T1 Port

In the ATM mode, multiple E1 ports, as IMA links, are bundled in an AIM group. When

some E1 links are interrupted, the services carried over the E1 ports are transferred to

other E1 links.

In the IP mode, multiple E1 ports, as PPP links, are bundled in a MLPPP group. When

some E1 links are interrupted, the services carried over the E1 ports are transferred to

other E1 links.

3.2.3 Backup of SDH Port

SDH ports can be backed up in three modes: port backup plus board backup, APS, and

load sharing of optical port.

Port backup plus board backup: The board backup mode is 1+1 backup. At a time, the

optical port in the active board receives and transmits data. In case the port of the active

board is faulty, the active/standby switching is triggered. The optical port of the new

active board is active for transmitting and receiving data.

APS: Support the APS for the optical ports in a board and the optical ports between

boards. For details on APS, refer to ZTE UMTS ATM Transmission Feature Guide.

Load sharing of optical port: The board backup mode is 1:1 backup. At a time, the

optical ports of the active and standby boards both transmit and receive data. The data

received by the optical port of the standby board is forwarded to the active board.

3.2.4 Backup of Level-1 Switch Optical Port

The Level-1 switch system is an IP packet switching system, which mainly comprises

GUIM, GLI, and PSN boards. The GLI and the PSN are cross-connected through a



HSSL. The PSN boards work in the load sharing mode, that is, two PSN boards switch

packets at the same time. The port backup mode is applied between GLI boards. The

GLI boards are cross-connected to the GUIM boards in another shelf respectively. At

each end, every GE port has two optical modules for backup. Through active/standby

port backup and optical module backup, the backup proportion between physical links

and logical links is 4:1, thus providing a reliable link assurance for the access of IP

packets to the switching center.

The GUIM has two GE ports. Active/standby GE port backup is accompanied by board

backup. Every GE port has two optical modules. The GLI has four GE ports, and every

GE port has two optical modules. The two GE ports with the same GLI sequence

number have an active/standby relation. The active/standby relation between the GE

ports with different sequence numbers is independent from each other. 0 lists the GE

ports supported by the GUIM/GLI.

Table 3-4 GE Ports Supported by the GUIM/GLI

Board Number of GE Ports Number of Optical Modules per GE Port

GUIM 2 2

GLI 4 2

Every GE port has two optical modules, thus enabling the double-t ransmitting & one-

receiving mechanism through hardware. Both optical modules transmit data to the

external world. At a time, only the active optical port receives data. The hardware also

provides the switching function for the packet-receiving optical module.

The following section describes the inter-shelf fiber interconnection mode in detail.

3.2.4.1 GUIM-GLI Interconnection

In the GUIM, there are two optical ports interconnected to the GLI. The active/standby

relation between the two optical ports is also accompanied by board backup. In normal

cases, the two optical ports both forward the media streams. Traffic balance is attained

between the two GE ports in the GUIM through a certain algorithm. The system

compares the number of the available GE ports in the boards. The system prefers the

GUIM with a larger number of available optical ports as the active end. In case the GE

port of the active GUIM is faulty, board switching is initiated. 0 shows the detailed

connection mode.



Figure 3-31 GUIM-GLI Connection

1

2

3

4

GLI#1

1

2

3

4

GLI#2

2

1

GUIM

#1

2

1

GUIM

#2

3.2.4.2 Interconnection between GUIM Boards in Two Shelves

In a small switch office, the GLI-PSN switch mode is not needed. Instead, the GUIM-

GUIM double-shelf interconnection mode is enough for the service traffic. In this case,

the following double-shelf interconnection mode can be used. Unlike the GUIM-GLI

interconnection, only one optical port is provided for interconnection in this mode, as

shown in Figure 3-32.

Figure 3-32 Double-Shelf Interconnection Between GUIM Boards

GUIM#1

GUIM#2

GUIM#3

GUIM#4



3.3 Redundancy Protection of Communication Link

3.3.1 ATM Link Backup

ATM link backup is configured through the bottom-layer redundant link. According to the

link status, the upper-layer application selects an available link for backup. The link

status is fed back by monitoring the on/off state of the physical layer, and is obtained

through the OAM check of the ATM.

3.3.2 IP Link Backup

IP link backup is configured through route redundancy. According to the link status, the

upper-layer application selects an available route for backup. The link status can be

obtained by monitoring the on/off state of the physical layer or through the IP layer

detection protocol (for example, BFD). In case an external interface of the system is

faulty, the route related to the faulty interface also fails. When sending data, an

application selects another route. If the BFD mechanism detects that the corresponding

route is not available, the application does not select the corresponding route, either.

Instead, the application selects another normal route.

For details about BFD, refer to ZTE UMTS IP UTRAN Feature Guide.

3.3.3 SCTP Link Backup

SCTP uses the Multihomed SCTP mechanism, that is, support the multi -access mode.

In a SCTP couple, there are multiple pairs of IP addresses that support the transmission

of SCTP data. In case a pair of IP channels is interrupted, the status of the SCTP couple

is not affected.

3.3.4 Data Division Transmission Backup

When multiple interfaces (of the same type or different types) support the transmission

of the same service, the data transmitted through a faulty interface is migrated to

another normal interface.

4 Parameter Description

4.1 Parameter List

4.1.1 Configuration Information on Board Redundancy Protection

No. Abbreviated name Parameter name



1 BackUpMode Backup Mode

2 RcpModule RCP Module

3 SubSystem SubSystem

4.1.2 Configuration Information on Port Redundancy Protection

For details on the parameters related to APS of optical ports, refer to ZTE UMTS ATM

Transmission Feature Guide.

4.1.3 Configuration Information on Communication Link Redundancy Protection

For details on the BFD parameters of the IP link, refer to ZTE UMTS IP UTRAN Feature

Guide.

4.2 Parameter Configuration

4.2.1 Configuration Information on Board Redundancy Protection

4.2.1.1 Backup Mode

OMC Path

Path: View->Configuration Management ->RNC NE->RNC Ground Resource

Management-> RACK->Create->Board->Available Board

Parameter Configuration

Related description

None

Interface parameter description:

The parameter indicates the backup mode of boards. Its value is as follows:

0 No backup

1 1+1 backup (the name is BOARD_BACKUP_MODE_MASTERSLAVE; only one

board is running normally at any time)

2 Load sharing (load sharing or port backup only applies to the boards in adjacent

slots)



3 Back-to-back backup (not used currently)

4 N+1 backup

5 1:1 backup

Note: The backup mode is specified when the corresponding boards are configured.

Recommendation: Configure the backup mode according to the field networking

mode

4.2.1.2 Rcp Module

OMC Path


Management-> RACK->Create->Board->RCP-> Module 1 / Module 2


Related description

None

Interface parameter description:

The parameter indicates the module number of the RCP. Its value is 3 to 127.

Recommendation: none

4.2.1.3 Sub System

OMC Path


Management-> RACK->Create->Board->RCP-> Module 1 / Module 2


Related description

None

Parameter description: none

The parameter indicates the subsystem number of the resource shelf of the RCP.

Its value is 0 to 19. The invalid value is 0xFF. When the Iub interface is carried in

the ATM, the available SubSystem [0] of the RCP must be the resource shelf that is



accessed by Node B under the jurisdiction of the RCP, and the number of available

shelves is 1.

4.2.2 Configuration Information on Port Redundancy Protection

N/A.

4.2.3 Configuration Information on Communication Link Redundancy

Protection

N/A.

5 Counter and Alarm

5.1 Counter List

N/A.

5.2 Alarm List Alarm Code 198005376

Description Internal Port of Board Is Down

Severity Level Level 2

Cause

1. The number of internal ports configured for this board and the neighboring slots exceeds the number of physical slots.

2. Pin Healthy of this slot on the backplane is damaged.

Alarm Code 198066003

Description Control plane communication abnormal between board and its home module


Cause

1. The board is configured in the database but not powered on.

2. The board is powered on but the control plane link to its home MP is broken.

3. The board is powered on and DIP switch ENUM is switched on.


Description Board HW Error




Cause

1.The NE clock is abnormal.

2. The TDM connection chip is abnormal.

4. The board hardware has faults.

5. The back board hardware has faults.


Description Board Doesn't Exist/ CPU is in Reset Status for a Long Time


Cause

1. The board configured in the database is not on position.

2. An error occurs during board resetting.

3. Pin Healthy of this slot on the backplane is damaged.


Description Control plane communication abnormal between MP and OMP


Cause

1. The MP board is configured in the database but not powered on.

2. The MP board is powered on but the control plane link to the OMP is broken.

3. The MP board is powered on and DIP switch ENUM is switched on.


Description Input Clock Abnormal


Cause The clock board runs exceptionally, and is not in the normal

working status. No clock reference is input to the c lock board or the clock reference is exceptional.


Description External Port of Board Is Down


Cause

1.The network interface at the local end or the peer end is faulty.

2.The work modes of network interfaces at both ends do not match.

3. Physical connection has faults.

4.The GEMAC on this board does not support the 100M speed of the negotiate mode.




Description DSP Resource Unavailable


Cause

1. DSP does not succeed in loading the version and can not work normally.

2. DSP has HPI interface exception.

3. The media plane loop back fails.

4. Lan91 link is broken.

5. The link of 5328 port is broken.

6. DSP running halts.

7. The system initialization of the Tone resource DSP fails. Different formats of tone resources or even no tone resource exists on the board.


Description Clock reference source lost (Level 3 alarm)


Cause Clock reference lost is detected for the first time.




Cause Clock reference lost has been detected for more than 10 minutes.




Cause Clock reference lost has been detected for more than 24 hours.


Description Communication Link between Active and Standby Boards Off


Cause

1. Active and standby boards are configured on OMC, but no standby board is physically plugged.

2. The communication link between active and standby boards is off.




Description Notification of Active/Standby Changeover

Severity Level Notification Level 4

Cause It is hardware system fault. The active and standby boards switch over due to artificial operation.


Description Physical link down between active port and standby port


Cause Physical Link Down Between Active Port and Standby Port


Description The rate of error code in a mate link is high at GUIM


Cause The rate of error code in a mate link is high. It is adventive

6 Glossary

AC Access Control

APBI ATM Process Board Interface

APBE ATM Process Board Enhanced Version

APS Automatic Protection Switching

ATM Asynchronous Transfer Mode

BHCA Busy-Hour Call Attempts

BME Base station Multiplex Equipment

BM-SC Broadcast Multicast Service Centre

BRS Bearer Subsystem

CBC Cell Broadcast Centre

THUB Trunk HUB

CN Core Network

DASF Dynamic Radio Bearer Control



DBS Data Base Subsystem

DDN Digital Data Network

zte umts ran equipment redundancy feature guide

Documents