1© 2000, Cisco Systems, Inc. IEEE SRP Tutorial March 2000

Spatial Reuse Protocol:Spatial Reuse Protocol:A Ring BasedA Ring Based

LAN / MAN / WANLAN / MAN / WANMAC ProtocolMAC Protocol

Mike TakefmanMike Takefman

2IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SRP GoalsSRP Goals

• Improve economics via layer eliminationand BW multiplication

• Provide fast protection and restoration

• Enable Plug and Play operation

• Support LAN, MAN and WAN applications

3IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

Dedicated AccessPoP Ring

LeasedLines

Cable DataAccess Ring

Metro Access Ring

Server AccessRing

RegionalTransport

Ring

BackboneRing

RegionalTransport

Ring

HFCHFCHFCHFC

HFCHFC HFCHFC

SiSi

SRP ApplicationsSRP Applications

4IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

• Accepted transportarchitecture

• Performance monitoringand self-healing

• Expensive andinefficient for packets

Multiple equipment layers

Bandwidth inefficiency

SONET/SDH-BasedSONET/SDH-BasedTDM TransportTDM Transport

ProvisionedConnectionsProvisionedConnections ProtectionProtection

SONETADM

SONETSONETADMADM

SONETADM

SONETSONETADMADM

SONETADM

SONETSONETADMADM

WorkingWorkingSONET

ADMSONETSONET

ADMADM

SONET/SDHRing

5IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

•Runs over dark fiber, SONET, or WDM

•Enables transport “mix and match”

•Provides efficient evolution path for existing networks

•Provides optimized transport for greenfield builds

Transport Flexibility andTransport Flexibility andEvolutionEvolution

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SRPRing

WDM ~~~~~~~~~~~~

Dark Fiber

6IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

• Existing topologiesFDDI ringSwitched FDDIATM or Fast EthernetPoint-to-point POS

• IssuesBW limitsComplex load balanceMultiple boxesPort counts

Previous Intra-POPPrevious Intra-POPConnectivity OptionsConnectivity Options

SharedFDDI Ring

Internet Backbone

622 Mb/s ATM1 Gbps Ethernet

622-MbpsPOS

155- or 622- Mbps ATM100-Mb Ethernet

Internet Backbone

622-MbpsPOS

155-Mbps POS

Internet Backbone

FDDISwitch

XX XX

Internet Backbone

7IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SRP OverviewSRP Overview

• Maximize BW efficiency

dual counter rotating ringsdestination strippingstatistical muxing of BFP

• Extend IP functionalityover MAN & WAN

• Minimize provisioningand configuration

8IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SRP OverviewSRP Overview

• Multicast support

• 2 Traffic priorities on ring

High priority traffic has low latency patharound ring

SRP fairness algorithm (SRP-fa) controlsaccess to ring BW for low priority traffic

• 8 priority levels for Tx and Rx queueing

9IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SRP Cooperates with Layer 3 CoSSRP Cooperates with Layer 3 CoSto Extend Functionalityto Extend Functionality

• Layer 3 provides rich functionality and granular controls• MAC provides speed and simplicity• Enables low delay/jitter for voice and video packets

Layer 3—IPLayer 3—IP

Layer 2— SRP MACLayer 2— SRP MAC

Precedence Setting Rate Control

Congestion ControlRED/WRED

Granular SchedulingDRR on Eight Classes

Big Fat Pipes

High-Priority Bypass

Low-Priority Fairness

Precedence Mapping

10IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

• SRP fairness algorithm

Distributed algorithm

Propagates and usesMAC usage info

Source and forward ratecontrols

Rapid adaptationand convergence

(1)(1)

(4)(4)

(2)(2)

(5)(5)(3)(3)

SRP OverviewSRP Overview

Node 1Node 1

Node 2Node 2

11IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SRP OverviewSRP Overview

• Scalable: Bit-rate; Circumference ofring; Up to 128 nodes

• Intelligent Protection Switching (IPS)

Survivability in the event of single fiber /node failure, or signal degradation

• Media independent protocol

Initial implementation uses SONET/SDHframing

12IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SRP PacketSRP Packet

• SRP is a media independent MAC layer protocol• The initial implementations utilizes Byte

Synchronous HDLC within SONET/SDH framing(OC-12c, OC-48c, OC-192c)

• Allows transport via: Dark Fiber; SONET/SDH;WDM

TransportTransportOverheadOverhead

PathPathOverheadOverhead

FFLLAAGG

MACMACHeaderHeader

PayloadPayloadFFLLAAGG

FFCCSS

PayloadPayload

13IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

Comparison with DQDBComparison with DQDB

• No segmentation and reassembly

complete packets stored and forwarded

• Distributed fairness without master nodes

• Protection switching without master

• High priority traffic for delay sensitiveapplications

No support for isochronous traffic

14IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

Comparison with FDDIComparison with FDDI

• Greater than 2x bandwidth improvement

both rings carry traffic

Destination stripping allows spatial reuse

• No token to pass

• FDDI-2 supported isochronous traffic &master node

not generally implemented

15IEEE SRP Tutorial March 2000 © 2000, Cisco Systems, Inc.

SummarySummary

• Scalable packet ring technology

Bit-rate; Number of Nodes; RingCircumference

• High bandwidth efficiency

• Cost effectiveness

• Distributed fault tolerance

• LAN, MAN and WAN applications