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 PayloadPayload
FFLLAAGG
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