alcatel - isa ethernet technical description

ED 01 - CONFIDENTIAL It.01

All

right

s res

erve

d. P

assi

ng o

n an

d co

pyin

g of

this

do

cum

ent,

use

and

com

mun

icat

ion

of it

s con

tent

is n

ot

perm

itted

with

out w

ritte

n au

thor

izat

ion

from

Alc

atel

site

VIMERCATE TRANSMISSION SYSTEMS

Originator(s)

M. RICCI

ISA Ethernet

Technical description

Domain : ALCATEL OPTICSDivision : Transmission Network Division Rubric : OMSN Product Management Type : Distribution code Internal External X

ABSTRACT

This document technically describes the architecture and the basic provisioning of the ISA Ethernet plug-in module for Metro OMSN product family

HISTORY

ED 01 IT 01 2002/03/19 Draft Technical description of Rel.1.

TND ISA_Eth_tech_ED_10.doc 1/4


All

right

s res

erve

d. P

assi

ng o

n an

d co

pyin

g of

this

do

cum

ent,

use

and

com

mun

icat

ion

of it

s con

tent

is n

ot

perm

itted

with

out w

ritte

n au

thor

izat

ion

from

Alc

atel

1. INDEX 1. INDEX..............................................................................................................................................................2 2. GENERAL DESCRIPTION.............................................................................................................................2 3. ARCHITECTURE............................................................................................................................................3 4. PROVISIONING..............................................................................................................................................4

2. GENERAL DESCRIPTION ISA Ethernet provides 10/100baseT interfaces in Metro OMSN family allowing the interconnection of two LANs in a point to point configuration as in Figure 1. The card acts as a gateway towards the SDH network.

OMSN withOptical Ethernet ISA

SDH Ring/Network

Customer Box:either LAN Switch or Router

Ethernet frame mapped in SDH VC

Ethernet frame de-mapped from SDH VC12, VC3, VC4

SDH level Protection

The Optical Ethernet ISA Boards are present only at

each terminating node

Site to Site Traffic is mapped on dedicated

SDH VC

Figure 1 – ISA Ethernet: Network view

The traffic received by the 10baseT or 100baseTX Ethernet interfaces on the ISA Eth card is mapped into VC12, VC3, or VC4 SDH transport structures, more precisely the Ethernet traffic passing through 1 x Ethernet physical interface is mapped into one specific VC-n (n=12, 3, 4). Each Ethernet frame is mapped without modifications into a Generic Framing Procedure frame (GFP – ITU-T G.7041). Such GFP frame is afterwards mapped inside the specific VC-n according to SDH standard protocol stack as represented in Figure 2.

EthernetEthernetGFPGFPSDHSDH

Figure 2 - ISA Ethernet: Protocol Stack and Buffering

In fact the Ethernet traffic is transported transparently by the SDH Network and the ISA Eth card inside an OMSN extracts and receives the Ethernet traffic coming from LAN switches or routers without “terminating” the Ethernet frames.

The nominal peak-rate of Ethernet is 10 Mb/s and Fast Ethernet is 100 Mb/s hence mapping of a full-rate Fast Ethernet in VC-4 and full-rate Ethernet in VC-3 does not require any buffering stage.

In order to better take advantage of the available resources and allowing the deployment of standard 10/100baseT interfaces even if no full-rate is required by the end user, the mapping represented in Figure 2, is provided. This mapping introduces the rate-adaptation feature in the traffic flow, while taking into account the bursty profile of the Ethernet traffic.



All

right

s res

erve

d. P

assi

ng o

n an

d co

pyin

g of

this

do

cum

ent,

use

and

com

mun

icat

ion

of it

s con

tent

is n

ot

perm

itted

with

out w

ritte

n au

thor

izat

ion

from

Alc

atel

The rate adaptation relies on the introduction of a buffer (see Figure 3) that acts as a bucket which smoothes the bursty Ethernet traffic. The peak rate that the card is able to adsorb without discarding any Ethernet packet/frame is directly proportional to the bucket “depth”. In practice no discarding can be achieved because the ISA Eth card features the mechanism of traffic flow control specified in IEEE 802.3x. Thanks to this control, when the buffer reaches a fixed threshold a particular frame is generated communicating to the Source (i.e. LAN switch or router) to stop its transmission for a certain time period (specified in this frame). In this way frame discarding is avoided.

Ethernet Sink

GFPEncapsulationElastic

Buffer

SDH Mapping

EthernetEthernet EthernetEthernet EthernetEthernet

Ethernet I/F

Figure 3 – ISA Ethernet: Rate Adaptation and buffering

3. ARCHITECTURE The architecture of the ISA Eth card is represented in Figure 4. ISA Ethernet is made of two cards:

1. Port-card: main card providing 11 Ethernet 10/100BaseTX auto-sensing interfaces 2. Access-card: expands the number of auto-sensing 10/100BaseTX ports of the main card with

14 additional 10/100BaseTX auto-sensing interfaces The Ethernet traffic, specifically mapped in the SDH transport structures, is transmitted from the ISA Ethernet plug-in module toward the SDH matrix through the back-plane (which has 4 STM-1 equivalent throughput), then the SDH matrixes connects each VC-n with the appropriate STM-n port card to the WAN transmission side. The bandwidth associated to each 10/100baseT interface is such that the 25 interfaces within a single slot ISA Ethernet plug-in module, considered all together, cannot transport more than 4 x VC-4 payload equivalent bandwidth.



All

right

s res

erve

d. P

assi

ng o

n an

d co

pyin

g of

this

do

cum

ent,

use

and

com

mun

icat

ion

of it

s con

tent

is n

ot

perm

itted

with

out w

ritte

n au

thor

izat

ion

from

Alc

atel

ISA EthPort Module

x I/F

ISA EthAccessModule

x I/F

ISA EthPort Module

x I/F

ISA EthAccessModule

x I/F

SDH PORTSDH PORT

STM

STM

--NN RX

TX

TX

RX

SDH PORTSDH PORT

STMSTM--NN

SDH MATRIXSDH MATRIX

SDHXconnection

SDHVC

Backplanebus

connections

ISA EthPort Module

x I/F

ISA EthAccessModule

x I/F

ISA EthPort Module

x I/F

ISA EthAccessModule

x I/F

11

14

11

14

11

14

11

14

Figure 4 – ISA Ethernet: System architecture

4. PROVISIONING The operator provisioning main options are:

1. 10bseT interface traffic mapped into: – 1 x VC-12 or – 1 x VC-3;

2. 100baseTX interface traffic mapped into: – 1 x VC-12 or – 1 x VC-3 –1 x VC-4.

The operator will always have to provision for each 10/100baseT interface:

1. Type of interface (Ethernet or Fast Ethernet) 2. Mapping in SDH resources (see above) 3. Sensing behavior (Manual or Automatic)

a. The Manual sensing implies that the interface types are explicitly manually chosen in terms of rate (10 or 100 Mb/s) by both the LAN switch/router and the OMSN with ISA Eth card installed.

b. The Automatic sensing implies that the interface types (10baseT or 100baseTX) are negotiated with standard auto-sensing procedure by both the LAN switch/router and the OMSN with ISA Eth card installed. Automatic sensing requires the mechanism of auto-sensing to negotiate the parameters between the two interfaces (local: OMSN and remote: LAN switch/router). These parameters are: – Rate (10/100Mb/s) – Directionality: half-duplex or full duplex. Having ISA Eth Full-duplex interfaces the

negotiation will agree always this type of connection. Note that half-duplex interfacing method is unreliable when applied to large-scale geographical networks and therefore results obsolete in these applications.

– IEEE 802.3x Flow-Control activation always considering that the back-panel is able support a maximum throughput of 4 x VC-4.


alcatel - isa ethernet technical description

Documents