2-broadband networks and atm
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8/12/2019 2-Broadband Networks and ATM
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IEEE Communications standards*
Standard Also known as Medium Access Topology /frequency band
IEEE 802.3 LAN/Eathernet Metcalfe /Xerox CSMA/CD Star to olo
IEEE 802.4 LAN (developed by General motors) Token Bus Bus topology
IEEE 802.5 LAN (developed by IBM) Token Ring Ring topology
. . .
IEEE 802.15.1
IEEE 802.15.4
PAN/Bluetooth (developed by
Ericsson)
PAN/ZigBee/WSN (Wireless Sensor
-- ISM band at 2.4GHz
ISM bands**
RF
&
2.4GHz
e wor s --
IEEE 802.16d
IEEE 802.16e
IEEE 802.16j
BWA/Fixed WiMAX
BWA/Mobile WiMAX
BWA/Relay WiMAX
OFDM
OFDMA
OFDMA
2 GHz to 66 GHz (initially 10 GHz
to 66 GHz was allocated for LOS
but to support NLoS 2 GHz to 11
IEEE 802.16m BWA/Very high data rate OFDMA GHz was allocated later)
IEEE 802.20 MBWA/Mobile-Fi ( Will support
connectivity up to 250 km/h mobile
-- Licensed Bands (below 3.5 GHz)
*IEEE provides communication standards for Physical & MAC layer only
** ZigBee operating frequencies 868 MHz in Europe, 915 MHz in the USA and Australia, and 2.4 GHz rest of the world
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• Broadband networks can be classified as
– Wide Area Network (WAN) (Transports signals over longdistances)• Optical fiber backbone network
• ease nes
• Satellites Communication
• Telecommunication networks (BS to BS or backbone network)
– Access network (BS or local exchange to customer • Cable modem , DSL & ADSL
•
• WiMAX
• Telecommunication Networks from BS to MS (3G networks likeUMTS/CDMA 2000)
BS=Base StationMS= Mobile Station
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. as tec no ogy
• WiMAX stands for Worldwide Interoperability for Microwave Access
• WiMAX forum is a non-profitable group
• WiMAX forum ensures the interoperability of devices developed by various
vendors using IEEE 802.16 specifications
• WiMAX forum Promote the development and deployment of WiMAX
systems
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• CBR constant bit rate:
• VBR(Variable bit rate)• ABR (Available Bit Rate:-minimum guarantee rate)
• UBR (Unspecified bit rate: Traffic is allocate to all)
• Services based on type of QoS (Quality of Service)
– UGS (Unsolicited Grant Service)
– ert s extended real time ollin service
– rtps (real tile polling service)
– nrtps (non real time polling service)
–
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CIF/SIFD= connection
Identifier/Subscriber
identifier
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•
• Internet
• ATM
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• Developed by Metcalfe's (Xerox company got patent)
• MAC address (48 bits) is used as address of a device.• CSMA/CD is used for multiple access.
•
• Pure Eathernet is no more in use, at present combination of Eathernet andn erne s use n .
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• Develo ed b IETF
• TCP/IP protocol suite covers network and transport layers.
• IP address are used for addressing of devices.
• Packet size is variable
• Two versions IPv4 (32 bits) and IPv6 (128 bits) are available
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• Developed by ITU-T
• Combination of best features of circuit switched & acket
switched networks• It uses asynchronous time division multiplexing
• Packet size is fixed (53 Bytes = 5 header +48 payload)
• ATM is a vital part of B-ISDN, SONET and several
telecommunication backbone/backhaul network technolo ies.
• It’s a Virtual Circuit switched network (connection oriented)
(three phases are Set-up connection, transfer data and tear down
connection)
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• The ATM reference model is com osed of the followin lanes
which span all layers: – Control —This plane is responsible for generating and managing
.
– User —This plane is responsible for managing the transfer of data.
– Mana ement — This
lane contains
two
com onents:
• layer management that manages layer‐specific functions, such as the
detection of failures and protocol problems
•
system.
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• The ATM reference model is composed of three ATM layers:
– h sical la er: mana es the medium-de endent transmission
– ATM Layer: provides cell multiplexing, cell-switching and routing services. To dothis, it uses the VPI and VCI information in the header of each ATM cell.
– ATM adaptation layer: segments the data into 48-byte cell payloads.
• There are five types of ATM Adaptation Layers (AAL)
– AAL1: (CBR) used for voice and videoconferencing
– AAL2: (VBR) real time or non real time voice or video bursts in nature
– AAL3 and AAL 4:VBR services, supports both connection‐oriented and
connectionless data
– AAL5: used for Data services, supports both
connection
‐oriented
and
connectionless data, example IP over ATM.
• Which AAL is used in a cell is not encoded in the cell, it is negotiated
between end devices prior to data transmission
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ATM Virtual Connections
Virtual Paths
Physical Link
Virtual Channels
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Exam le of Virtual ath & Virtual Channel in ATM
NN: Network Node
CPN: Customer
Premise
Node
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1. ATM network is organized as a hierarchy.
User’s e ui ment connects to networks via a U I User-Network
Interface). Connections between provided networks are made through NNI
- .
2. ATM is connection-oriented .
A connection (an ATM channel) must be established before anycell/Packet transmission.
3. Two levels of ATM connections:
virtual channel connections
4. Indicated by two fields in the cell header:
virtual path identifier (VPI)
virtual channel identifier (VCI)
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Private
UNI
Private ATM
network ATM Network Architecture
X X
Private
NNI Public ATM
X X
network A
X
NNI
Public
UNI
X
B‐ICI Public ATM
network B
X X
Public
UNI
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ATM Network Architecture Two types of networks are included in the ATM architecture:
Private Networks: Customer Premises Networks, permit the use of lower
traffic speed
Public Networks : supports Wider area
UNI: User to Network Interface
NNI: Network to Network Interface (Three types of NNI)
NNI-ISSI Inter‐Switchin
S stem
Interface
that connects switches in the
same Local Transport Area
NNI-ICI (Inter Carrier Interface) that connects ATM networks of different
carriers
Private NNI that connects different switches in a private network.
BICI: Broadband Inter Carrier Interface
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UNI Cell Format
GFC (4 bits) VPI (4 bits)
VPI (4 bits) VCI (4 bits)
VCI (8 bits)
CLP
ATM cell header
VCI 4 its PT 3 its(1 bit)
HEC (8 bits)
Payload
(48 bytes)
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GFC (4 bits): Generic Flow Control
"uncontrolled access" this field is set to all zeroes
controlled access t is ie is set to all ones w en congestion as occurre .
VPI (8 bits): Virtual Path Identifier VCI (16 bits): Virtual Channel Identifier
PTI 3 bits : Pa load T e
use information or Layer Management Information
CLP (1 bit): Cell Loss Priority
Indicates the cell's priority in the ATM selective loss algorithm. Set by the initiatingequ pmen , w en s se o , e ce s g ven pre erence over ce s w se o
1 during cell discarding (loss) process.
HEC (8 bits): Header Error Control
Provides a capability to correct all single bit errors in the cell header as well as the
detection of the majority of multiple-bit errors.Payload (48 Bytes): User or management Data
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Pa load T e 3 bits)
cont.
•The first bit indicates the type of ATM cell that follows. A first bit set to
0 n cates user ata; a t set to 1 n cates operat ons, a m n strat on &
management (OA&M) data.
journey from source to destination. This bit is also called the Explicit
Forward Congestion Indication (EFCI) bit. The second bit is set to 0 by
cell, it sets the bit to 1. After it is set to 1, all other switches in the path
leave this bit value at 1.
Destination ATM end oints can use the EFCI bit to im lement flow
control mechanisms to throttle back on the transmission rate until cellswith an EFCI bit set to 0 are received.
•The third bit indicates the last cell in a block for AAL5 in user ATM
cells. For non-user ATM cells, the third bit is used for OA&M functions.
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VPI (12 bits): Virtual Path Identifier
VCI (16 bits): Virtual Channel Identifier
PTI (3 its): Pay oa Type
use information or Layer Management Information
CLP 1 bit : Cell Loss Priorit
Indicates the cell's priority in the ATM selective loss algorithm. Set by the initiating
equipment, when this set to 0, the cell is given preference over cells with CLP set to 1.
s : ea er rror on ro
Provides a capability to correct all single bit errors in the cell header as well as the
detection of the majority of multiple-bit errors.
Payload (48 Bytes): User or management Data
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Data transmission through ATN network
User
information
User
information
AAL AAL
ATM ATMATM ATM
PHYPHY PHY PHY
…
End system End
systemNetwork
Cell Switching and Routing is performed in ATM Layer
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