An Introduction To RPR
John Lemon Chair, IEEE 802.17 Senior Staff Scientist, ADTRAN Agenda
Overview Features How it works Questions
An Introduction To RPR 3 Overview What
Resilient packet ring IEEE Std 802.17-2004 Primarily for metropolitan area networks Alternative to TDM and mesh networks Medium access control method and physical layer specification ± Physical layer agnostic
An Introduction To RPR 5 Who
Best of Cisco DPT, Luminous RPT, and Nortel IPT Additions from WG Products offered by ADTRAN, Alcatel-Lucent, Cisco, Huawei, Nortel, «
An Introduction To RPR 6 When
Study Group formed May 2000 Working Group created December 2000 Standard approved September 2004 802.17a approved September 2004 ± Adds support of 802.17 to 802.1D bridging standard 802.17b approved March 2007 ± Adds spatial reuse to bridged and multicast traffic 802.17c started March 2007 ± Adding Protected Inter-Ring Connection (PIRC)
An Introduction To RPR 7 Why
SONET viewed to have problems with ± Equipment expense ± Operational difficulty ± Provisioning lag time ± Efficiency ± Fairness Ethernet viewed to have problems with ± SLAs ± Resiliency ± Fairness Both ± Limitations in physical layers
An Introduction To RPR 8 Features Features «
Resiliency ± Sub 50 ms detect and repair ± Lossless ± No single point of failure Efficiency ± Spatial reuse ± Temporal reuse Real SLAs ± Each class of traffic guaranteed its needs ± Not relative QoS
An Introduction To RPR 10 Features (continued)
Fairness ± Weighted fairness Not necessarily equality Plug-and-play ± No single point of control ± Little or no provisioning ± Topology flexible ± Capability flexible
An Introduction To RPR 11 How Resiliency
Choice of two sub-50 ms protection mechanisms ± Steering: optimized for minimizing packet re-ordering for TDM and video services and to preserve bandwidth utilization Default protection method that is always supported ± Wrapping: optimized to minimize immediate packet-loss for data services Optional protection method that may be supported
An Introduction To RPR 13 Topology Aware Protection
Wrapping Wrapped path wraps at both A and E Topology information Break in path from B to D used at edges A
Original path from B to D
Continued use during protection Unplanned use B during protection E
Steered path is steered at B
Unplanned use during protection
D Steering C Topology information used at source
An Introduction To RPR 14 Protection Protocol
Send local information on changes and periodically ± TP frame sent 8 times fast (10 ms), then slow (100 ms) ± TC frame sent 4 times fast, then reverts to slow Update database with new received information, and calculate local and remote edge & protection states ± Includes detecting a station entering or exiting passthrough²changing presence on ring without intervening disconnection (AKA optical passthrough) Alter local edge/protection states, if preempted Update reachability and validity information in database
An Introduction To RPR 15 Efficiency
Spatial reuse ± Packets removed from the ring at destination ± Remainder of ring not occupied with wasted traffic Temporal reuse ± Unused BW reclaimed and distributed
An Introduction To RPR 16 Real SLAs
BW allocations restored upon demand ± Class based prioritization allows restoration within delay and jitter requirements for SLAs ± Allows full utilization and hard SLAs without reserving BW FR/ATM-derived classes of service
Class of service Quality of service Name Example use Subclass Guaranteed Delay/jitter Bandwidth Bandwidth bandwidth type subtype classA real time subclassA0 yes low allocated reserved subclassA1 reclaimable classB near real time classB-CIR yes bounded allocated classB-EIR no unbounded opportunistic classC best effort
An Introduction To RPR 17 Fairness
S1 S2 S3 S1 S2 S3 S1 S2 S3 6 Mb/s 6 Mb/s 6 Mb/s 6 Mb/s 6 Mb/s 6 Mb/s 6 Mb/s 6 Mb/s 6 Mb/s equal unequal w w w weighted 6w 2w 2w weighted 0 Mb/s shapers shapers 2 Mb/s 4 Mb/s 3.3 Mb/s 10 Mb/s 2 Mb/s available 3.3 Mb/s capacity 6 Mb/s 6 Mb/s 3.3 Mb/s
Unfairness Equal Fairness Weighted Fairness
An Introduction To RPR 18 Fairness Concepts
KEY Fairness rate advertising downstream congested (advertisedRate < FULL_RATE) Fairness rate advertising downstream uncongested (advertisedRate == FULL_RATE) data frame
tail congestion head domain A local station congestionPoint hopsToCongestion
ringlet0 data
S0 S1 S2 S3 S4 S5 not part of not part of any ringlet0 fairness any congestion message feedback congestion domain domain S254 S9 S8 S7 S6
congestion domain B head tail
An Introduction To RPR 19 Spatial Reuse and Fairness
Node A reduces red traffic, not Increased utilization blue traffic of fiber by re-using A bandwidth on all ring H B spans Congestion notification ± Destination stripping C G ± Ring spans following Node C destination are Node C reduces available for additional experiences green congestion D traffic traffic F E
An Introduction To RPR 20 Assuring SLA At Each Node
+ + 3 Best Effort services
Single SLA-based services Out-of-profile customerƞs Classify Traffic services to Dedicated TB BW services Ring P In-profile + 2 Token Bucket shaper TB Discard Excess Rate 1 Rate policer P +
An Introduction To RPR From other customers 21 Bandwidth Sharing/Scheduling Dedicated BW Shared BW SLA Shared BW best services based services effort services Out-Of-Profile (EIR) P P P P P P In-Profile (CIR) B A Send Send C Within Within Send Within provisioned provisioned fair rates rates MAC-client usage MAC AB C Congestion P P F? message Fair usage expected A Ringlet PTQ 3 4 Rx 2 Ringlet Tx Class? 1 + B & C STQ 5 An Introduction To RPR 22 Additional Fairness Rules
Scheduled only if: Dedicated BW Shared BW SLA Shared BW best services based services effort services ± No imminent Out-Of-Profile (EIR) P loss in STQ P P P P P Scheduled to In-Profile (CIR) B fair rate if: A Send Send C Within Within Send Within provisioned provisioned ± Congestion fair rates rates MAC-client usage present MAC AB C Congestion P P message downstream F? Fair usage expected A Scheduled to Ringlet PTQ 3 4 Rx 2 Ringlet Tx full rate when: Class? 1 + B & C STQ 5 ± Above conditions don¶t An Introduction To RPR exist 23 Plug-And-Play
Every station on a ring knows: ± What other stations are on the ring ± The topology of the ring ± The protection status of all the stations ± The attributes of all the stations Time critical information sent via TP frames Less time-critical information sent on changes and periodically, via ATD frame (1 s) On receipt of TP or ATD frames, local database updated with new information, ring-wide values calculated An Introduction To RPR 24 Topology Protocol
Send local information on change & periodically via shared use of TP frame Update database with new received information, and calculate hops away, reachable, valid, etc. Validate database ± Consistency (e.g., if A-B-C on ringlet0 then C-B-A on ringlet1) ± All reachable stations valid ± Fewer than MAX_STATIONS Compare checksum with neighbor during validation (for context containment)
An Introduction To RPR 25 Automatic Topology Discovery
Local topology A Topology and Protection information is broadcast (TP) frames periodically and provide local information triggered on change
B E
Topology Checksum (TC) frames D provide local view Each station computes full C of topology topology independently and compares with neighbors periodically and triggered on change An Introduction To RPR 26 RPR For MSOs Bundled Services for SMB
Headend
Voice/TDM Switch Router 10Mb RPR DS3 MTU
OC3 GE
10Mb RPR
T1 Business B
RPR 50Mb
T1 Business A
An Introduction To RPR 28 Multi-Site Service
Headend
Voice/TDM 10Mb Switch Router T1 Branch C 100Mb
RPR OC3 OC3 GE MTU
10Mb RPR
T1 Branch A
RPR 100Mb
T1 Headquarters
An Introduction To RPR 29 Remote Access Service
Headend Voice/TDM 10Mb Switch Router T1 Branch C 100Mb
RPR OC3 OC3 GE MTU
10Mb RPR 1 T Branch A
RPR 100Mb
T1 Headquarters An Introduction To RPR 30 Mixed Metro Access
Branch Small Office GbE Office Mobile Base Station Branch Office Park I nternet & 10/100 10/100 T1 &/or POTS GbE T1 10/100
AN POP Hospital GbE Multiport GbE Aggregation Point / Enterprise Campus CMTS Head End GbE
10/100
SM Businesses
T1 or 10/100 Residential Customers Company HQ
T1 School/ ¡ollege WiFi Hotspot Internet & GbE GbE POTS CMTS GbE
¡MTS
An Introduction To RPR Residential Customers Residential ¡ustomers 31 For More Information
Website: http://grouper.ieee.org/groups/802/17/ Free copy of the standard: http://standards.ieee.org/getieee802/802.17.html
An Introduction To RPR 32 Questions?