Download ECE544

ECE544: Communication
Networks-II, Spring 2010
D. Raychaudhuri
Lecture 3
Includes tutorial materials from the ATM Forum & U VA
Today’s Lecture
• Switched Networks
– Switched Ethernet
• Concepts
• Learning bridge, spanning tree
– ATM networks
• Overview
• Signaling
• PNNI Routing (basics)
Ethernet Hub
• Used to connect hosts to Ethernet LAN and to
connect multiple Ethernet LANs
• Collisions are propagated
Ethernet
Hub
Ethernet
Hub
Host
Host
IP
IP
LLC
LLC
802.3 MAC
Hub
Hub
802.3 MAC
Bridges/LAN switches
• We will use the terms bridge and LAN switch (or
Ethernet switch in the context of Ethernet)
interchangeably. Interconnect multiple LAN,
possibly with different type
• Bridges operate at the Data Link Layer (Layer 2)
Tokenring
Bridge
IP
IP
Bridge
LLC
802.3 MAC
LLC
LAN
802.3 MAC
LLC
802.5 MAC
LAN
802.5 MAC
Ethernet Hubs vs. Ethernet Switches
• An Ethernet switch is a packet switch for Ethernet
frames
• Buffering of frames prevents collisions.
• Each port is isolated and builds its own collision domain
• An Ethernet Hub does not perform buffering:
• Collisions occur if two frames arrive at the same time.
Hub
Switch
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
CSMA/CD
HighSpeed
Backplane
CSMA/CD
Input
Buffers
CSMA/CD
CSMA/CD
Output
Buffers
A Switched Enterprise Network
Internet
Router
Switch
Need for Routing
• What do bridges
do if some LANs
are reachable
only in multiple
hops ?
• What do bridges
do if the path
between two
LANs is not
unique ?
LAN 2
d
Bridge 4
Bridge 3
Bridge 1
LAN 5
Bridge 5
LAN 1
Bridge 2
LAN 3
LAN 4
Transparent Bridges
• Three principal approaches can be found:
– Fixed Routing
– Source Routing
– Spanning Tree Routing (IEEE 802.1d)
• We only discuss the last one in detail.
• Bridges that execute the spanning tree algorithm
are called transparent bridges
Transparent Bridges
Three parts to transparent bridges:
(1) Forwarding of Frames
(2) Learning of Addresses
(3) Spanning Tree Algorithm
(1) Frame Forwarding
• Each bridge maintains a forwarding database
with entries
< MAC address, port, age>
MAC address:
port:
age:
host name or group address
port number of bridge
aging time of entry
with interpretation:
• a machine with MAC address lies in direction of the port
number from the bridge. The entry is age time units old.
(2) Address Learning (Learning Bridges)
• Routing tables entries are set automatically
with a simple heuristic:
The source field of a frame that arrives on a port tells
which hosts are reachable from this port.
Src=x, Dest=y
Port 1
Port 4
x is at Port 1
y is at Port 5
Port 2
Port 5
Port 3
Port 6
Src=x, Dest=y
Example
•Consider the following packets:
(Src=A, Dest=F),
(Src=C, Dest=A), (Src=E, Dest=C)
•What have the bridges learned?
Bridge 2
Port1
Bridge 2
Port2
LAN 1
A
B
Port2
Port1
LAN 2
C
LAN 3
D
E
F
Danger of Loops
• Consider the two LANs that are
connected by two bridges.
• Assume host n is transmitting a
frame F with unknown destination.
F
What is happening?
• Bridges A and B flood the frame Bridge A
F
to LAN 2.
• Bridge B sees F on LAN 2 (with
unknown destination), and copies
the frame back to LAN 1
• Bridge A does the same.
• The copying continues
LAN 2
F
Bridge B
F
LAN 1
F
host n
Spanning Trees / Transparent Bridges
• A solution is to prevent loops in the
topology
LAN 2
• IEEE 802.1d has an algorithm that
organizes the bridges as spanning tree
in a dynamic environment
– Note: Trees don’t have loops
d
Bridge 4
Bridge 3
Bridge 1
LAN 5
• Bridges that run 802.1d are called
transparent bridges
Bridge 5
LAN 1
• Bridges exchange messages to
configure the bridge (Configuration
Bridge Protocol Data Unit, Configuration
BPDUs) to build the tree.
Bridge 2
LAN 3
LAN 4
ATM Overview
•
•
•
•
•
•
Introduction
Physical Layers
ATM Layer
ATM Adaptation Layer
Interfaces
Management
ATM Basic Concepts
• Negotiated Service Connection
– End-to-end connections,
called virtual circuits
– Traffic contract
• Switched Based
– Dedicated capacity
• Cell Based
– Small, fixed length
A
Negotiated Service
Connection
Traffic Contract
 Parameters
 Traffic Characteristics
 Peak Cell Rate
 Sustainable
Cell Rate
 Quality of Service
 Delay
 Cell Loss
Virtual Connection 1-QOS A
Virtual Connection 1-QOS B
Virtual Connection 1-QOS b
The ATM Cell
Header
Payload
5 Bytes
48 Bytes
• Small Size
– 5 Byte Header
– 48 Byte Payload
• Fixed Size
• Header contains virtual circuit information
• Payload can be voice, video or other data
types
A
ATM Vision
The Ultimate Integrated Services Network
Voice
Voice
Data
Voice
Video
ATM
Network
Data
Data
Video
Video
• ATM network moves cells (fixed length packets) with low delay
and low delay variation at high speeds
• Devices at ends translate (e.g., segment and reassemble)
between cells and original traffic
ATM System Architecture
Voice
Cell
Data
Cell
Video
Cell
A
ATM Adaptation Layer
AAL
Types
1
Circuit Emulation
-Constant Bit Rate (CBR)
2
Low Bit Rate Voice (Real Time)
48 Bytes
-Variable Bit Rate (VBR)
3/4
5
Time Invariant Data
“Simple” Data
• Provides Mapping Of Applications To ATM
Service Of The Same Type
• Segments/Reassembles Into 48 Payloads
• Hands 48 Byte Payloads To ATM Layer
A
ATM Layer
48-Byte
Payloads
From AAL
5-Byte Header
}
53-Byte Cell
To Physical Layer
Header Contains Virtual
Path
and Channel Identifiers
• Adds/Removes Header To 48 Byte Payload
• Header Contains Connection Identifier
• Multiplexes 53 Byte Cells Into Virtual
Connections
• Sequential Delivery Within A Virtual
Connection
A
Physical Layer
Speed Matching
and Framing
Cable
Plants
Uses Existing Media
Wide Range of
Speeds
Twisted Pair
Coax
Transmission
Frame
Fiber
LAN, MAN, WAN
-Multimode
Compatibility
-Single Mode
A
ATM System Architecture
ATM Cell Creation Transmission
Forward Cell
Through
Conversion to
Network
ATM Data
Types, 48-Byte
Length
Add 5-Byte
Header
Services
Adaptation
Layer
ATM
Layer
Convert To
Correct
Electrical Or
Optical
Format
Voice
Cell
Data
Cell
Video
Cell
Physical
Layer
A
Private UNI PHY
ATM Forum Physical Layer UNI Interfaces
Frame Format
Bit Rate/Line Rate
Transmission Media
Cell Stream
25.6 Mb/s / 32 Mbaud
UTP-3
STS-1
51.84 Mb/s
UTP-3
FDDI
100 Mb/s / 125 Mbaud
MMF
STS-3c, STM-1
155.52 Mb/s
UTP-5, STP
STS-3c, STM-1
155.52 Mb/s
SMF, MMF, Coax pair
Cell Stream
155.52 Mb/s / 194.4 Mbaud
MMF/STP
STS-3c, STM-1
155.52 Mb/s
UTP-3
STS-12, STM-4
622.08 Mb/s
SMF, MMF
STS-48, STM-16*
2,488.32 Mb/s
SMF
*-Under Development
SMF-Single Mode Fiber
MMF-Multimode Fiber
UTP-Unshielded Twisted Pair
STP-Shielded Twisted Pair
DS1 and DS3-Also Private Speeds
B
Public UNI PHY
ATM Forum Physical Layer UNI Interfaces
Frame Format
Bit Rate
Transmission Media
DS1
1.544 Mb/s
Twisted Pair
DS3
44.736 Mb/s
Coax Pair
STS-3c, STM-1
155.520 Mb/s
SMF
E1
2.048 Mb/s
Twisted Pair, Coax Pair
E3
34.368 Mb/s
Coax pair
J2
6.312 Mb/s
Coax pair
N X T1
N X 1.544 Mb/s
Twisted pair
N X E1
N X 2.048Mb/s
Twisted pair
*-Under Development
SMF-Single Mode Fiber
PLCP-Physical Layer Convergence Protocol
B
ATM PHY: Two Sublayers
Transmission Convergence
Sublayer
Physical Layer Medium Dependent
Sublayer
• PMD:
– Medium, line code, connectors
– Probably use existing standards and technology
• TCS:
– Specific to the PMD
– Cell delineation
– Cell rate decoupling (inserting empty cells during idle periods)
155 Mbps, SONET STS3c/SDH
STM-1
270 columns
9
R
o
w
s
...
Maintenance
and
operations
1 Synchronous
Payload Envelope
(1 column of overhead)
125 msec
9 bytes
• 9  260  8/125 msec = 149.76 Mbps
payload
A
HEC Cell Delineation
(For SONET, etc...)
Peek ahead at the cell format
HEC (Header Error Check)
Header
Payload
Coverage of the 1 byte HEC
Receiver locks on 5 byte blocks that
Satisfy the HEC calculation
Are separated by 48 bytes
HEC includes coset so that empty cell (first 4 bytes of
header = 0) does not make HEC = 0
A
1.5 Mbps, DS1
125 msec
...FBB...BFB...BF...
24 bytes
Framing Bit
• (24 bytes x 8 bits/byte)/125
msec=1.536 Mbps of payload
• Cell delineation by HEC detection as
with SONET
• Cell payload=1.536 Mbps x
(48/53)=1.391 Mbps
25.6 Mbps UTP-3
• Based on IEEE 802.5 physical layer
with 4B/5B coding plus scrambling
• 32 Mbaud x 4/5 = 25.6 Mbps
• Cells delineated by special symbol
pairs
x x
Cell
Reset Scramble
or
x 4
Cell
No Scramble Reset
A
ATM UNI Cell
7
6
5
4
3
2
1
0
Generic Flow
Control
Virtual Path Identifier
Virtual Path Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
5 Bytes
CLP
Header Error
Check
Payload
(48 bytes)
CLP = Cell Loss Priority
48 Bytes
Why 53 Bytes?
64 + 5
32 + 4
48 + 5
• Compromise reached in ITU-TS
Study Group XVIII in June 1989
Packetization Delay
Advantage of Small Cells
Percent Overhead and Packetization Delay
for 64 Kbps Voice
Delay
80
10
8
Overhead
60
6
40
4
20
2
0
0
80
0
20
40
Payload (Bytes)
60
Delay (ms)
% Overhead
100
Queuing Advantage of Small
Cells
100 byte message
100 other active
connections
45 Mbps
•
•
•
Max
Delay
(ms)
12
10
8
6
4
2
0
High overhead
Wait for other cells
Just fits in one cell
1
50
100
150
200
Payload (bytes)
250
300
Delay and delay
variation are
small for small
messages e.g.,
a digitized voice
sample
A
7
Virtual Connections
76
Video
Video
42
4
Data
88
Voice
52
Data
22
Video
1
37
Video
78
Voice
5
2
6
Connection Table
Video
Data
Video
Voice
Port
1
1
2
2
VPI/VCI
0/37
0/42
0/37
0/78
Port
3
5
6
4
5
4
3
VPI/VCI
0/76
0/52
0/22
0/88
2
1
0
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
Header Error
Check
Payload
(48 bytes)
3
37
6
Generic Flow
Control
CLP
Virtual Paths and Virtual
Channels Physical Link
7
6
5
4
3
2
1
0
Generic Flow
Control
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
Header Error
Check
Payload
(48 bytes)
Virtual Path
Virtual Channel
CLP
7
Virtual Paths and Virtual
Channels
6
5
4
3
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
Header Error
Check
VPI = 4
VCI = 55
VCI = 57
VPI = 2
VPI = 5
VCI = 31
VCI = 40
VCI = 99
VCI = 32
VPI = 3
VCI = 96
VCI = 97
0
Virtual Path
Identifier
ATM Switch or Network
VCI = 31
VCI = 32
1
Virtual Path
Identifier
Payload
(48 bytes)
VPI = 1
2
Generic Flow
Control
VPI = 6
VCI = 96
VCI = 97
• Bundles of Virtual Channels are switched via
Virtual Paths
• Virtual Path service from a carrier allows
reconfiguration of Virtual Channels without
service orders to carrier
CLP
7
Cell Loss Priority
6
5
3
2
1
0
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
• Cells with bit set should be discarded
before those with bit not set
• Can be set by the terminal
• Can be set by ATM switches for internal
network control
– Virtual channels/paths with low quality of
service
– Cells that violate traffic management
contract
• Key to ATM Traffic Management
4
Generic Flow
Control
Payload Type
Identifier
Header Error
Check
Payload
(48 bytes)
CLP
7
Generic Flow Control
6
5
4
3
2
1
0
Generic Flow
Control
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
CLP
Header Error
Check
Payload
(48 bytes)
•
•
•
•
Used for UNI only - Not NNI
Currently undefined
Set to 0000B
Proposed future uses
– Flow control
– Shared media multiple access
B
7
Header Error Check
6
5
4
3
2
1
0
Generic Flow
Control
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
• Header error control
Payload Type
Identifier
CLP
Header Error
Check
Payload
(48 bytes)
– Detection mode:
• Protects header only (all five bytes)
• Discards cell when header error
– Correction mode (optional): Correct 1 bit
errors else discard when error detected
• Reduced cell loss in face of single bit errors
• Reduced error detection for multiple bit errors
• Cell delineation for SONET, SDH, etc...
• Recalculated link-by-link because of
VPI/VCI value changes
B
Permanent Virtual Circuits
VPI/VCI
VPI/VCI
VPI/VCI
VPI/VCI
Network
Management
System
• Long setup time (especially with human intervention)
means that connections are left active for long periods of
time e.g., days, weeks
• VPI/VCI tables setup in terminals and switches
B
Switched Virtual Circuits
Signalling Channel
(VPI/VCI = 0/5)
Signalling Channel
(VPI/VCI = 0/5)
Call
Processing
ATM Switch
• Switch and terminal exchange signalling
messages using the predefined signalling
channel, VPI/VCI = 0/5
B
Point-to-Point Connection
• Data may flow in one or both directions
(unidirectional or bidirectional)
• Bandwidth may be:
– Same in both directions (symmetric), or
– Different in each direction (asymmetric)
Point-to-Multipoint
Connection
“Root”
• Data are replicated
by the network
• Data flow only from
Root to Leaves
“Leaves”
Why SVCs?
• Universal connectivity
• More efficient resource utilization
A
Call Control Signalling
Call control protocol is used to establish,
maintain, and clear virtual channel
UNI or NNI
User
connections between aNetwork
user and network
Call Control
Signalling
UNI
Call Control
Signalling
Virtual
Channel
Connections
Interface
UNI or NNI
Signalling 4.0
• Delta from Q.2931 etc.
• Extensions for parameterized QoS, ABR,
LIJ
• Some restrictions
Signalling Protocol Stack
UNI 4.0
Q.931
Q.2931
Q.921
LAPD
SSCOP
I.430/431
ISDN UNI
ATM
SONET/DS3
ATM UNI
Setting Up a Call - 1
A wants to communicate with B
A
B
Setup
Call
Proceeding
• Setup message
–
–
–
–
–
Call reference
Called party address
Calling party address
Traffic characteristics
Quality of service
• Call proceeding
message
– Call reference
– VPI/VCI
B
Setting Up a Call - 2
Setup
Call
Proceeding
• Internal network
processing
– Resource
availability
checking
– Virtual channel or
path routing
– Function of the
Network Node
Interface (NNI)
B
Setting Up a Call - 3
Setup
Setup
Call
Proceeding
Call
Proceeding
• Setup message
–
–
–
–
–
–
Call reference
Called party address
Calling party address
Traffic characteristics
Quality of service
VPI/VCI
Call Proceeding
Call reference
Called user deciding
to accept call
B
Setting Up a Call - 4
Setup
Setup
Call
Proceeding
• Connect message
– Call reference
– Indicates call
acceptance
Call
Proceeding
Connect
Connect Ack
• Connect Acknowledge
– Call reference
B
Setting Up a Call - 5
Setup
Setup
Call
Proceeding
Call Proceeding
Connect
Connect
Connect Ack
Connect Ack
• Calling party informed that call is
available for user information exchange
B
ATM Addressing
• Private networks
– 20 byte address
– Format modeled after OSI NSAP (Network Service
Access Point)
– Mechanisms for administration exist
– Hierarchical structure will facilitate virtual
connection routing in large ATM networks
• Public networks
– E.164 numbers (telephone numbers)
– Up to 15 digits
• Private networks
– MAC address will be encapsulated within NSAP
B
Address to Endstation
ATM End
System
Address
Format
Native
E.164 or
AESA
Public
ATM
Network
Private ATM Switch
Private
UNI
Public
UNI
ATM End System Address
AESA
Format
Based on ISO NSAP Format
End
SystemSupplied
NetworkSupplied
39 DCC
HO-DSP
End System ID
SEL
SEL
IDC
HO-DSP
End System ID
SEL
SEL
End System ID
SEL
47
45
Private
UNI
E.164 Number
HO-DSP
• Selector (Not used by
Network for Routing)
Private Address Formats
Data Country Code
39
DCC
Routing Fields
End System ID
SEL
End System ID
SEL
End System ID
SEL
International Code Designator
47
Routing Fields
ICD
E.164 Private Address
45
E.164 Number
Routing Fields
D
Address Registration
• Allows automatic configuration
• Required at the private UNI
• Optional at the public UNI
• Network supplies the network prefix
• User supplies the user part
Subaddress Use
• Subaddress:
– Used to convey an AESA across a public network which
supports only E.164 addresses
– Also can be used for NSAP
Private UNI
Address: AESA
Subaddress: NSAP or Not Used
Public UNI
Address: E.164 Public Network Address
Subaddress: AESA
Subaddress IE: Only present if used for NSAP at
Private UNI
Private
Network
Private
Network
Public
Network
A
Messages and Information
Elements
Type Length
Message
Header
Type
Length
Value
IE1
Type
Length
Value
IE2
Type
Length
IE3
• Very flexible and extensible encoding
• 19 message types
• Around 35 IEs
….
AAL1: Adaptive Clock Method
Received Cells
Reconstructing the bit stream
Continuous Bit
Stream
Speed up bit
Substitute Cells clock
Slow down bit
clock
Water Mark
• Bit stream rate is independent of ATM
network and (theoretically) can be any value
• Cell delay variation is critical to buffer sizing
and bit clock jitter
B
AAL2
• Small payload to reduce packetization delay
User 1
User 2
User 3
User 1
User 3
ATM Cell
Cell Header
(5 Octets)
AAL2 Header
(3 Octets)
AAL2 Payload
(variable)
B
AAL3/4
0 - 65535
Bytes
Data
4
Bytes
4 or 8
Error
Checking
Error
Checking
2
44
2
M
I
D
User Data
C
R
C
• 44 Bytes of Data per Cell
• CRC Checking per Cell
• Message Identifier (MID)
Allows Multiple Interleaved
Packets on a Virtual
Connection
2
44
2
M
I
D
User Data
C
R
C
2
M
I
D
44
2
User Data
C
R
C
44
M
I
D
Pad
C
R
C
D
AAL 5
• 48 Bytes of Data
per Cell
• Uses a PTI Bit to
Indicate Last Cell
• Only One Packet
at a Time on a
Virtual
Connection
0 - 65535
Bytes
Data
Error detection fields
0-47 2 2 4
Pad 0
L
e
n
Bytes
C
R
C
48
0
...
48
1
Last cell flag
Not drawn to scale
C
7
Quality-of-Service
6
5
4
3
2
0
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
Header Error
Check
• Problem: Providing quality of service
1
Generic Flow
Control
Payload
(48 bytes)
– How should ATM network resources be allocated to ensure
good performance including preventing congestion, e.g.,
how many virtual channels should be assigned to a
particular transmission link?
• Solution: Traffic Management
– Specify the traffic "contract" on each virtual channel/path
– Route (including rejecting setup request) each virtual
channel/path along a path with adequate resources
(Admission Control)
– Mark (via Cell Loss Priority bit) for loss all cells that violate
the contract (Traffic Policing)
CLP
ATM Service Categories
• CBR
– Constant Bit Rate
– Continuous flow of data with tight bounds on delay and delay variation
• rt-VBR
– Real-Time Variable Bit Rate
– Variable bandwidth with tight bounds on delay and delay variation
• nrt-VBR
– Non-Real-Time Variable Bit Rate
– Variable bandwidth with tight bound on cell loss
• UBR
– Unspecified Bit Rate
– No guarantees (i.e., best effort delivery)
• ABR
– Available Bit Rate
– Flow control on source with tight bound on cell loss
Quality of Service
Parameters
•
•
•
•
•
•
End to end transit delay
Acceptable CDV (Forwards, Backwards)
Cumulative CDV (Forwards, Backwards)
Cell Loss Ratio (Forwards, Backwards)
Encoded as two IEs
QoS Classes may also be indicated for
backwards compatibility
Generic Cell Rate Algorithm
7
6
5
4
2
1
0
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
I for each cell arrival
3
Generic Flow
Control
Payload Type
Identifier
CLP
Header Error
Check
Payload
(48 bytes)
• For a sequence of cell arrival times,
{tk}, determines which cells
conform to the traffic contract
• A counter scheme based on two
parameters denoted GCRA(I,L)
L+I
– Increment parameter: I
• affects cell rate
– Limit parameter: L
One unit leak per
unit of time
• affects cell bursts
• “Leaky bucket”
– A cell that would cause the bucket to
overflow is non-conforming
7
Payload Type Identifier
6
5
4
3
2
1
0
Generic Flow
Control
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
• Bit 3: Used to discriminate data cells
from operation, administration,
maintenance cells.
• Bit 2: Used to indicate congestion in
data cells (Bit 3 = 0)
Payload Type
Identifier
CLP
Header Error
Check
Payload
(48 bytes)
– Set by Switches
– Source and Destination Behavior Defined for
Available Bit Rate Flow Control VCC’s
• Bit 1: Carried transparently end-to-end
in data cells
– Used by AAL5
C
7
ABR Feedback
Forward RM* Cells
5
4
3
2
1
0
Virtual Path
Identifier
Virtual Path
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
CLP
Header Error
Check
Payload
(48 bytes)
+
Source
Rate & Congestion
Indication
6
Generic Flow
Control
+
Congestion
Indication
Rate
Indication
+
+
Destination
+
Backward RM* Cells
• Source sets Actual Cell Rate based
on rate & congestion feedback
*- Resource Management
B
Actual
Cell Rate
Peak
Cell Rate
Minimum
Cell Rate
Network Congestion
Example Source Cell Rate
Profile
Time
C
Bandwidth Negotiation
UNI
Setup
(20 Mb/s)
Connect
(10 Mb/s)
NNI
Setup
(15 Mb/s)
Connect
(10 Mb/s)
UNI
Setup
(10 Mb/s)
Connect
(10 Mb/s)
Other ATM Interfaces
Private
NNI
Private
UNI
Public
NNI
Metropolis Data
Services Inc.
ATM
DXI
Public
UNI
FUNI
FUNI
UNI
NNI
B-ICI
ATM DXI
FUNI
User Network Interface
Network Node Interface
BISDN Inter-Carrier Interface
Data eXchange Interface
ATM Frame Based UNI Interface
B-ICI
Country Wide Carrier
Services
D
NNI
Cell Format
7
6
5
4
3
2
1
0
Virtual Path Identifier
Virtual Path Identifier
Virtual Path Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Virtual Channel
Identifier
Payload Type
Identifier
Header Error
Check
Payload
(48 bytes)
CLP = Cell Loss Priority
CLP
• Supports 212 Virtual Paths
• Supports virtual connection
routing
– Distribution of topology
information
– Distribution of resource
availability information
• Public version being
standardized by ITU TS
• Private version specified by
ATM Forum Technical
Working Group
C
B-ICI
• For interfaces between public carriers
• Based on carrier digital transmission
– DS3, 44.736 Mbps
– STS-3c, 155.52 Mbps
– STS-12c, 622.08 Mbps
• Supports multiple carrier services
– Cell Relay Service (PVC)
– Circuit Emulation Service (Synchronous
Residual Time Stamp, PVC)
– Frame Relay Service (PVC)
– Switched Multi-megabit Data Service
D
ATM Network Management
Management
System
M1
UNI
ATM
Device
M3
M2
Private
ATM
Network
Management
System
M5
M4
UNI
Public
ATM
Network
Management
System
M4
BICI
Public
ATM
Network
ILMI:
Integrated Layer
Management Interface
C
Today’s Homework
• Peterson & Davie, Chap 3
-3.1 (v3)
-3.5 (v3)
-3.7,8 (v3)
-3.13 (v3)
-3.26 (v3)
-3.30 (v3)
Download and browse ATM UNI4.0 and
PNNI1.0 specs
Due next Fri (2/19)
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