Introduction to ATM

1
Introductionto ATM
Original Susanne East seast_at_cisco.com
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2
Agenda

• Introduction
• ATM Fundamentals
• Rudimentary ATM Concepts
• ATM Reference Model
• ATM Adaptation Layer (AAL)
• Traffic Management
• Campus ATM Internetworking

3
Characteristics of ATM
Voice
Data
Cells
Video

• Uses small, fixed-sized cells
• Connection-oriented
• Supports multiple service types
• Applicable to LAN and WAN

4
Creating Cells from Packets
Dest.Address
SourceAddress
FrameCheck
Data
Packet
Payload
Header
Cells
Payload
Header
5 ByteHeader
Payload
Header
53Bytes
Payload
Header
48 BytePayload
ATM Cell
5
Campus Networking Evolution
Traditional Network
SharedEthernet Clients
Corporate WAN and Internet
LocalWorkgroupServers

• Hierarchical design with broadcast control
• 80/20 rule
• Homogenous user communities
• Moves, adds, and changes manually

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Campus Networking Evolution
Contemporary Network
SwitchedEthernetClients
Ethernet Switchwith VLAN Support
Corporate WAN and Internet
Campus ATM Network
Centralized High-Performance Servers
ATM-Attached Station(s)

• Network hierarchy maintained
• Traffic patterns migrating
• Client and server performance increases
• Moves, adds, and changes automated

7
The Wonderful World of Acronyms

• AAL?TM Adaptation Layer
• AAL1?ee CBR
• AAL2?ee VBR
• AAL3/4?ee UBR
• AAL5?ee ABR
• ABR?vailable Bit Rate
• API?pplication Programmer Interface
• B-ICI?-ISDN Inter-Carrier Interface
• BUS?roadcast and Unknown Server
• CAC?onnection Admission Control
• CBR?onstant Bit Rate
• CCITT?onsultative Committee for International
  Telephony and Telegraph
• CDVT?ell Delay Variation Tolerance
• CLP?ell Loss Priority
• CLR?ell Loss Ratio
• CS?onvergence Sublayer
• EFCI?xplicit Forward Congestion Indicator
• ELAN?mulated LAN
• GCRA?eneric Cell Rate Algorithm

8
The Wonderful World of Acronyms

• IPD?ntelligent Packet Discard
• LANE?ocal Area Network Emulation
• LEC?AN Emulation Client
• LES?AN Emulation Server
• LECS?AN Emulation Configuration Server
• LIS?ogical IP Subnet
• MBS?aximum Burst Size
• MCR?inimum Cell Rate
• MCTD?aximum Cell Transfer Delay
• MPC?POA Client (aka Edge Device)
• MPOA?ulti-Protocol Over ATM
• MPS?POA Server (aka Router Server)
• NNI?etwork-to-Network Interface
• OC?ptical Carrier
• PCR?eak Cell Rate
• PMD?hysical Media Dependent
• PNNI?rivate Network-to-Network Interface
• PTI?ayload Type Identifier
• PVC?ermanent Virtual Circuit

9
The Wonderful World of Acronyms

• SAR?egmentation and Reassembly
• SDH?ynchronous Digital Hierarchy
• SONET?ynchronous Optical Network
• STM?ynchronous Transport Mode
• STS?ynchronous Transport Signal
• SCR?ustained Cell Rate
• SVC?witched Virtual Circuit
• SSCOP?ignaling Specific Convergence Protocol
• TC?ransmission Convergence
• UBR?nspecified Bit Rate
• UNI?ser-to-Network Interface
• UPC?sage Parameter Control
• VBR-NRT?ariable Bit Rate-Non-Real Time
• VBR-RT?ariable Bit Rate-Real Time
• VC?irtual Circuit (or sometimes Virtual
  Connection)
• VCC?irtual Channel Connection
• VCI?irtual Channel Identifier
• VC Switch?irtual Circuit Switch
• VP?irtual Path

10
Agenda

• Introduction
• ATM Fundamentals
• Rudimentary ATM Concepts
• ATM Reference Model
• ATM Adaptation Layer (AAL)
• Traffic Management
• Campus ATM Internetworking

11
Rudimentary ATM Concepts

• Physical layer
• Signaling
• Cell format
• Connection types

12
ATM Transmission Media
ATM SDH/SONET Rates Chart
SDH
SONET
Rate?bps
STS-1/OC-1
51.84
STM-1
STS-3/OC-3
155.52
STM-4
STS-12/OC-12
622.08
STM-8
STS-24/OC-24
1,244.16
STM-16
STS-48/OC-48
2,488.32

• CCITT (Consultative Committee for International
  Telephony and Telegraph)
• ITU (International Telecommunications Union)

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ATM Physical Interface Rates
DataRate(Mbps)
Framing
Media
Multi-ModeFiber
Single-ModeFiber
CoaxialCable
UTP?
UTP?
STP
DS1E1J2DS3E3E4
1.5442.0486.234534139
(TP)(TP)
X
ATM25STS 1STS3c/STM1
25.651.8155
X
STS 12c/STM44B/5B (TAXI)8B/10B(Fiberchannel)
622100155
Standardized
Proposed/In Progress
X
14
Rudimentary ATM Concepts

• Physical layer
• Signaling
• Cell format
• Connection types

15
ATM Building Blocks

• ATM signaling
• UNI and NNI
• Virtual connections
• VCC, VP, and VC

16
ATM Signaling
Public UNIaka B-ICI
Public ATM Network
NNI
UNI
NNI
NNI
Private ATM Network

• UNI User-to-Network Interface
• NNI Network-to-Network Interface
• Cell header content varies depending on who?
  talking to whom

17
Virtual Path and Virtual Channels
Virtual Channels (VC)
ATM Physical LinkVirtual Channel Connection (VCC)
Virtual Path (VP)
E3OC?2
Virtual Path (VP)
Virtual Channels (VC)
Virtual Channel(VC)Logical PathBetween ATM End
Points
Virtual Path(VP)Contains Multiple VCs
Virtual Channel Connection(VCC)Contains
Multiple VPs
Connection Identifier VPI/VCI
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ATM Switches
Input
Output
45
VPI/VCI
Port
VPI/VCI
Port
29
1
45
2
64
29
45
2
29
1
64
1
29
3
29
3
64
1
29

• ATM switches translate VPI/VCI values
• VPI/VCI value unique only per interface?eg
  locally significant and may be re-used elsewhere
  in network

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VP and VC Switching
VC Switch
VCI 1
VCI 2
VCI 3
VCI 4
Port 2
VPI 2
VPI 3
VPI 1
VP Switch
VPI 2
Port 1
VCI 1
VPI 3
VPI 1
VCI 2
VCI 1
VPI 5
VPI 4
VCI 2
Port 3
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Virtual Channels and Virtual Paths
Virtual Channel Connection (VCC)
Virtual PathConnection (VPC)
UNI
UNI
NNI
NNI
VPSwitch
VCSwitch
VCSwitch
VPI 2VCI 44
VPI 1VCI 1
VPI 26VCI 44
VPI 20VCI 30

• This hop-by-hop forwarding is known as cell relay

21
Rudimentary ATM Concepts

• Physical layer
• Signaling
• Cell format
• Connection types

22
Creating Cells from Packets
Dest.Address
SourceAddress
FrameCheck
Data
Packet
Payload
Header
Cells
Payload
Header
SARSegmentation and Reassembly
Payload
Header
Payload
Header
Segmentation Happens at SourceReassembly Happens
at Destination
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ATM Cell Header
5 ByteHeader
53 Bytes
48 BytePayload
ATM Cell
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ATM Cell Header Details
GFC Generic Flow ControlUNI Cells
Only! VPI/VCI Identifies VirtualPaths and
Channels PTI Payload Type Identifier3 Bits 1.
User/Control Data2. Congestion3. Last
Cell CLP Cell Loss Priority Bit HEC Header Error
Check8 Bit CRC
25
Rudimentary ATM Concepts

• Physical layer
• Signaling
• Cell format
• Connection types

26
ATM Connection Types

• PVC
• SVC
• Soft PVC

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Connection Types
S2
S6
S1
S8
S3
S5
VC
S4
S7

• Connectionless Packet Routing
• Path 1 S1, S2, S6, S8
• Path 2 S1, S4, S7, S8
• Data can take different pathand can arrive out
  of order

• Connection Oriented Cell Switching
• VC S1, S4, S7, S8
• Data takes the same path and arrives in sequence

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Permanent Virtual Circuit (PVC)
Input
Output
Input
Output
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
1
33
3
02
1
29
3
45
2
15
3
14
2
52
4
15
29
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64
1
15
4
2
C
45
2
3
3
14
30
43
3
16
2
Input
Output
Input
Output
1
2
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
4
1
45
2
16
1
16
2
43
10
2
52
1
29
3
14
4
10
D
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64

• VPI/VCI tables in network equipment updated by
  administrator

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Switched Virtual Circuit (SVC)
Input
Output
Input
Output
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
1
29
3
45
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64
1
4
1
C
2
3
3
3
2
Input
Output
Input
Output
1
2
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
4
2
52
1
29
D
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64

• Dynamically set up connectionsvia signaling

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Switched Virtual Circuit (SVC)
Input
Output
Input
Output
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
1
29
3
45
1
29
3
45
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64
1
4
1
C
2
3
3
3
2
Input
Output
Input
Output
1
2
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
4
1
45
2
16
1
16
2
43
2
52
1
29
D
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64

• Transfer data over newly established link

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Switched Virtual Circuit (SVC)
Input
Output
Input
Output
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
1
29
3
45
1
64
3
29
1
64
3
29
A
3
29
1
64
3
29
1
64
1
4
1
C
2
3
3
3
2
Input
Output
Input
Output
1
2
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
4
2
52
1
29
D
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64

• Dynamically tear down connectionsvia signaling

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Soft PVC
Input
Output
Input
Output
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
1
29
3
45
1
29
3
45
1
64
3
29
1
64
3
29
A
3
29
1
64
3
29
1
64
1
3
C
1
Input
Output
Input
Output
2
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
Port
VPI/VCI
1
16
2
43
2
52
1
29
D
1
64
3
29
1
64
3
29
3
29
1
64
3
29
1
64

• PVC established manually across UNI and
  dynamically across NNI

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Agenda

• Introduction
• ATM Fundamentals
• Rudimentary ATM Concepts
• ATM Reference Model
• ATM Adaptation Layer (AAL)
• Traffic Management
• Campus ATM Internetworking

34
ATM Reference Model

• Physical layer
• ATM layer
• ATM adaptation layer
• A day in the life of a cell

35
ATM Reference Model
ATM Adaptation Layer (AAL)
ATM Layer
Physical Layer
36
ATM Reference Model
Physical Layer
ATM Adaptation Layer (AAL)

• Two Sublayers
• Transmission Convergence (TC)
• Framing
• HEC
• Physical Media Dependent (PMD)
• Physical media coding

ATM Layer
Physical Layer
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Physical Layer
DataRate(Mbps)
Framing
Media
Multi-ModeFiber
Single-ModeFiber
CoaxialCable
UTP?
UTP?
STP
DS1E1J2
1.5442.0486.23
(TP)(TP)
DS3E3E4
4534139
X
ATM25STS 1STS3c/STM1
25.651.8155
X
STS 12c/STM44B/5B (TAXI)8B/10B(Fiberchannel)
622100155
Standardized
Proposed/In Progress
X
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ATM Reference Model
ATM Layer
ATM Adaptation Layer (AAL)

• Cell header insertion/removal
• Cell Relay
• Multiplexes/demultiplexes cells of different
  connections

ATM Layer
Physical Layer
39
ATM Layer
Virtual Channel Connection (VCC)
ATM Adaptation Layer (AAL)
Virtual PathConnection (VPC)
UNI
UNI
ATM Layer
NNI
NNI
VPSwitch
VCSwitch
VCSwitch
Physical Layer
VPI 12VCI 44
VPI 0VCI 38
VPI 26VCI 44
VPI 0VCI 36

• Provides VPI/VCI values in header
• Ensures that cells stay in the correct order

40
ATM Reference Model
ATM Adaption Layer (AAL)
ATM Adaptation Layer (AAL)

• Two Sublayers
• Convergence Sublayer (CS)
• Segmentation and Reassembly (SAR)

ATM Layer
Physical Layer
41
ATM Adaptation Layer?AL
AAL
S A R
C S

• AAL QoS SAR
• CS?ssigns different AAL?/QoS for different
  traffic types
• SAR?ell lt-gt packet

42
ATM Adaptation Layer
ServiceCategories
Class
Bit Rate
ConnectionMode
TimingConcern
ApplicationExamples
ATM Adaptation Layer (AAL)

• Bandwidth andthroughput guaranteed
• Good for voice and video

AAL1
A
CBR(Constant)
Connection-Oriented
Yes

• Best effort bandwidth and throughput
• Good for live video,multimedia, LAN-to-LAN

AAL2
B
VBR(Variable)VBR-ATandVBR-NRT
Connection-Oriented
Yes
ATM Layer

• Best effort withcongestion feedback
• Reliable delivery of bursty traffic iflatency
  okay

AAL5
C
ABR(Available)
Connection-Oriented
No
Physical Layer

• No guarantee
• For SMDS/LAN

AAL3/4
D
UBR(Un-specified)
Connection-less
No
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ATM Reference Model

• Physical layer
• ATM layer
• ATM adaptation layer
• A day in the life of a cell

44
A Day in the Life of a Cell
ATM Payload Processing
TCP
TCP Packet
IP
IP Datagram
LLC/SNAP
ConvergenceSublayer (CS)
AAL
Put in 48 Byte Cells?AT into PDU
SAR
ATM
Add 5 Byte Headers with VPI/VCI and CLP
Transmission Convergence (STS, STM, DS)
PHY
Physical Media (MMF, SMF, STP, UDP,
45
A Day in the Life of a Cell
Traversing the Network
PHY
ATM
AAL
UNI
VPI 2VCI 37
NNI
ATM Switch
ATM Layer
Port 1
Port
VPI
VCI
PHY
ATM
1
1
51
2
3
39
VPI 3VCI 39
Port 2
PHY
ATM
PHY
ATM
AAL
UNI
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Agenda

• Introduction
• ATM Fundamentals
• Rudimentary ATM Concepts
• ATM Reference Model
• ATM Adaptation Layer (AAL)
• Traffic Management
• Campus ATM Internetworking

47
AAL

• AAL criteria
• Traffic parameters
• QoS parameters
• The AAL?
• AAL1?BR
• AAL2?BR
• AAL3/4?BR
• AAL5?BR

48
AAL Criteria
Contract
ATM Network
Contract

• Traffic Parameters
• Peak cell rate
• Sustainable cell rate
• Maximum burst size
• Minimum Cell Rate
• Quality of Service
• Delay
• Cell loss

49
AAL Criteria
Traffic Parameters

• Peak Cell RatePCR?aximum data rate a connection
  can handle without losing data
• Sustainable Cell Rate?CRAverage ATM cell
  throughput the application is permitted
• Maximum Burst Size?BS?ize of themaximum burst of
  contiguous cells that can be transmitted
• Minimum Cell Rate?CR?ate of anapplication?
  ability to handle latency

50
AAL Criteria
QoS?elay

• Maximum Cell Transfer DelayMCTD How long the
  network can take to transmit a cell from one
  endpoint to another
• Cell Delay Variation Tolerance?DVT Line
  distortion caused by change in interarrival times
  between cells aka jitter

51
AAL Criteria
QoS?ell Loss

• Cell Loss RatioCLR Acceptable percentage of cells
  that the network can discard due to congestion

52
Quality of Service?oS

• AAL criteria
• Traffic parameters
• QoS parameters
• The AAL?
• AAL1?BR
• AAL2?BR
• AAL3/4?BR
• AAL5?BR

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The AAL?
Real Time Voice and Video
AAL1?onstant Bit Rate (CBR)
QoS
Traffic Parameter
Tolerance
PCR
LOW
HIGH
Peak Cell Rate
Cell Loss
Cell Delay
Overhead
5 ByteHeader
1 Byte
47 BytePayload
54
The AAL?
Packetized Voice/Video, SNA
AAL2?ariable Bit Rate
(VBR-RT/VBR-NRT)
QoS
Traffic Parameter
PCR
Tolerance
Peak Cell Rate
LOW
HIGH
SCR
Sustainable Cell Rate
MBS
Cell Loss
Cell Delay(NRT)
Maximum Burst Size
Cell Delay (RT)
Overhead
5 ByteHeader
1?8Bytes
1?7 BytePayload
55
The AAL?
Public WAN?MDS
AAL3/4?nspecified Bit Rate (UBR)
QoS
Traffic Parameter
Tolerance
LOW
HIGH
No GuaranteesSend and Pray
Cell Delay
Cell Loss
Overhead
5 ByteHeader
44 BytePayload
4 Bytes
56
The AAL?
LAN Interconnect for Data
AAL5?vailable Bit Rate (ABR)
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Agenda

• Introduction
• ATM Fundamentals
• Rudimentary ATM Concepts
• ATM Reference Model
• ATM Adaptation Layer (AAL)
• Traffic Management
• Campus ATM Internetworking

58
Traffic Management

• Why traffic management?
• Traffic control techniques
• AAL5/ABR congestion feedback
• Buffers are your friend

59
Why Traffic Management?

• Proactively combat congestion
• Provision for priority control
• Maintain well-behaved traffic

60
Why Traffic Management?
Cell Loss?ata? Critical Enemy
Ethernet (1500 Bytes) 32 Cells FDDI (4470
Bytes) 96 Cells IP over ATM?577 (9180 Bytes)
192 Cells
TCP/IP Packet
X

• Lose one cell and the rest are useless
• Need to re-transmit 32 cells for one cell lost
• Congestion collapse is the result

61
Traffic Control Techniques

• Connection management?cceptance
• Traffic management?olicing
• Traffic smoothing?haping

62
Traffic Control Techniques
Connection Management
Contract
ATM Network
Contract

• Traffic Parameters
• Peak cell rate
• Sustainable cell rate
• Burst tolerance
• Etc.
• Quality of Service
• Delay
• Cell loss

63
Traffic Control Techniques
Connection Management Connection Admission
Control (CAC)
I want a VC X Mbps Y Delay Z Cell Loss
CAC Can I Support this Reliably without
Jeopardizing Other Contracts
Guaranteed QoS Request
No or Yes, Agree to aTraffic Contract
Contract
ATM Network
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Traffic Control Techniques
Traffic ManagementUsage Parameter Control (UPC)
aka Policing
You are Not in Conformance with the
Contract. What Should the Penalty Be??
Contract
?DECISION?
REBEL APPLICATION

• PASS
• MARK CLP BIT
• DROP

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Traffic Control Techniques
Traffic Management
UPC
Marked
0
0
0
0
1
0
?DECISION?
D r o p

• PASS
• MARK CLP BIT
• DROP

• CLP Control?hen congested drop marked cells
• Public UNI?eneric Cell Rate Algorithm (GCRA)

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Traffic Control Techniques
Traffic Management
UPC
Marked
0
0
0
0
1
0
D r o p
3
2

• Intelligent Packet DiscardIPD
• Discard cells from same ?ad?packet
• Tail packet discard
• Maximize Goodput

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Traffic Control Techniques
Traffic Smoothing
I Want to Comply With My Contract. So, I Will
Smooth/Shape My Traffic
Go Ahead, Make My Day
Shaper
Actual Data
Shaped Data
Private ATM Network
Public ATM Network

• Traffic shaper at customer site
• Changes traffic characteristics
• Leaky bucket algorithm

68
Traffic Control Techniques
AAL5/ABR Congestion Feedback

• RM?esource Management cells
• Rate-based feedback mechanisms
• EFCI marking
• Relative rate marking
• Explicit rate marking
• VS/VD

69
Traffic Control Techniques
AAL5/ABR Congestion Feedback
Forward
EFCI Set
EFCI Set
X
X
Destination
Source
RM
RM
X
X
Congestion Experienced Slow Down
Backward

• EFCI Marking?xplicit Forward Congestion Indicator
• Congestion flag set on forward cells only
• Destination end-system sends RM cells back to
  source

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Traffic Control Techniques
AAL5/ABR Congestion Feedback
Forward
RM
Destination
Source
RM
X
CongestionExperienced Slow Down ??Amount
Backward

• Relative rate marking
• Switches can set congestion flag in backward RM
  cells

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Traffic Control Techniques
AAL5/ABR Congestion Feedback
CongestionExperienced Slow Down X Amount
Forward
RM
Destination
Source
RM
Congestion Experienced Slow Down
Backward

• Explicit rate marking
• Switches can tell source at exactly what rate to
  transmit

72
Traffic Control Techniques
AAL5/ABR Congestion Feedback
Congestion Experienced Slow Down
Forward
Destination
Source
Backward

• VS/VD?irtual source/virtual destination
• Breaks the feedback loop into separate segments
• Shortens length of feedback loop

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Traffic Control Techniques
Buffers Are Your Friend

• Absorb traffic bursts from simultaneous
  connections
• Switches schedule traffic based on priority of
  traffic according to QoS
• Switch must reallocate buffers as the traffic mix
  changes
• Effective buffering maximizes throughput of
  usable cells as opposed to raw cells (aka goodput)

74
Agenda

• Introduction
• ATM Fundamentals
• Rudimentary ATM Concepts
• ATM Reference Model
• ATM Adaptation Layer
• Traffic Management
• Campus ATM Internetworking

75
ATM Internetworking

• Challenges
• RFC1483
• RFC1577
• LANE
• MPOA

76
ATM Internetworking
The Challenges
New Applications
Existing and New Applications
API
Network Address
MAC Address
???
ATM Address
ATM Address

• MAC address to ATM address resolution
• No Standard ATM API

77
ATM Internetworking
Overlay Model
ATM Addresses
Router or Switch
Router or Switch
ATM Network
Ethernet
Ethernet
Direct-Attached Stations
Network Addresses, MAC Addresses

• Multiple layers of addressing

78
ATM Internetworking
Solutions
Existing and New Applications
Existing and New Applications
Network Address
Network Address
MAC Address
MAC Address
RFC1483, RFC1577, LANE, MPOA
ATM Address
ATM Address
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ATM Internetworking
RFC 1483 Multiprotocol Encapsulation over ATM AAL5

• Encapsulation method used by other protocols
• Two methods
• LLC/SNAP?Logical Link Control/Sub-Network Access
  Protocol)
• VC Multiplexing?Virtual Circuit Multiplexing)

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ATM Internetworking
RFC 1483?xample
138.20.1.1
138.20.1.2
Routing Table
Address Resolution Table
ATM Network
138.20.10.X
DA-138.20.10.45

• Routing Table maps final destination to next hop
  network address
• Address Resolution table maps next-hop network
  address to ATM address?etup manually by network
  administrator
• Signaling creates ATM VC between routers

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ATM Internetworking
RFC 1577?lassical IP and ARP over ATM
ARP Server Subnet 1
ATM Network
ARP Server Subnet 2
LIS 1
LIS 2

• LIS?ogical IP subnet?n IP subnet
• ARP Server?aintains IP address to ATM address
  mappings
• One ARP Server per LIS
• No cut-through to alleviate router hops

82
ATM Internetworking
RFC 1577?xample
ARP Server
Routing Table
138.20.1.1
138.20.1.2
ATM Network
138.20.10.X
DA?38.20.10.45

• Routing table maps final destination to next-hop
• ATM ARP Server maps next-hop IP address to ATM
  addresses
• Signaling creates VC and data is passed

83
ATM Internetworking
LANE 1.0
ATM Network
Today? Physical LAN Segment
Emulated LAN (ELAN) Segment

• Hides ATM to upper layers
• Makes ATM look like Ethernet/Token Ring
• Supported in NICs, LAN switches, ATM routers
• Allows ATM hosts connectivity with legacy LANs

Cisco Systems Confidential
100
0680_03F7_c3
84
ATM Internetworking
LANE?asics
LEC?AN Emulation Client
LECS?AN Emulation Configuration Server for
Initialization
LES?AN Emulation Server for Address Resolution
BUS?roadcast and Unknown Server for Data Flooding
ATM

• Uses SVC? to establish conversations
• Uses RFC 1483 to transport LAN traffic

85
ATM Internetworking
LANE1.0?xample
The ATM ?11?Operator MAC Add ATM
Add xxx yyy aaa bbb
LECS
BUS
LES
ATM Switches
ATMAddresses
Ethernet MAC Addresses
LEC
LEC
Ethernet
ATM End-Station (eg, Server with ATM NIC)
86
ATM Internetworking
LANE 2.0

• Better efficiency of VC?
• Better use of ATM QoS
• Special multicast servers
• Server redundancy

87
ATM Internetworking
MPOA?ulti-Protocol over ATM

• For seamless transport of layer 3 protocols
  across ATM networks
• Goes beyond LANE by allowing direct ATM
  connectivity between hosts in different subnets
• Architecture consists of edge devices and route
  servers
• MPC?POA client?edge device
• MPS?POA server?route server

MPC
Resultant Direct Cut-Through between Different
VLANs
MPS
MPS
88
The ATM Forum

• Founded in fall of 1991
• Founding members Cisco Systems, NET, Nortel,
  Sprint
• Now over 700 members
• Working Groups Signaling, UNI, PNNI, LANE, MPOA
• http//www.atmforum.com

89
ATM References

• http//www.cisco.com
• http//www.atmforum.com
• or
• e-mail info_at_atmforum.com
• http//cell-relay.indiana.edu
• http//www.atmreport.com
• http//www.atm-user.com