Spatial Reuse Protocol: A Ring Based LAN / MAN / WAN MAC Protocol

Transcription

1 Spatial Reuse Protocol: A Ring Based LAN / MAN / WAN MAC Protocol Mike Takefman 1

2 SRP Goals Improve economics via layer elimination and BW multiplication Provide fast protection and restoration Enable Plug and Play operation Support LAN, MAN and WAN applications 2

3 Si SRP Applications Metro Access Ring Regional Transport Ring Leased Lines HFC HFC Backbone Ring Dedicated Access PoP Ring Cable Data Access Ring Regional Transport Ring Server Access Ring HFC HFC 3

4 /SDH-Based TDM Transport Accepted transport architecture Performance monitoring and self-healing Expensive and inefficient for packets Multiple equipment layers Bandwidth inefficiency Provisioned Connections /SDH Ring Protection Working 4

5 Transport Flexibility and Evolution Dark Fiber SRP Ring Runs over dark fiber,, or WDM Enables transport mix and match Provides efficient evolution path for existing networks Provides optimized transport for greenfield builds ~ WDM ~ 5

6 Previous Intra-POP Connectivity Options Internet Backbone Shared FDDI Ring Internet Backbone 622-Mbps POS 622 Mb/s ATM 1 Gbps Ethernet 155- or 622- Mbps ATM 100-Mb Ethernet Internet Backbone X FDDI Switch 622-Mbps POS X Internet Backbone 155-Mbps POS Existing topologies FDDI ring Switched FDDI ATM or Fast Ethernet Point-to-point POS Issues BW limits Complex load balance Multiple boxes Port counts 6

7 SRP Overview Maximize BW efficiency dual counter rotating rings destination stripping statistical muxing of BFP Extend IP functionality over MAN & WAN Minimize provisioning and configuration 7

8 SRP Overview Multicast support 2 Traffic priorities on ring High priority traffic has low latency path around ring SRP fairness algorithm (SRP-fa) controls access to ring BW for low priority traffic 8 priority levels for Tx and Rx queueing 8

9 SRP Cooperates with Layer 3 CoS to Extend Functionality Layer 3 IP Precedence Setting Congestion Control RED/WRED Rate Control Granular Scheduling DRR on Eight Classes Layer 2 SRP MAC Big Fat Pipes High-Priority Bypass Low-Priority Fairness Precedence Mapping Layer 3 provides rich functionality and granular controls MAC provides speed and simplicity Enables low delay/jitter for voice and video packets 9

10 SRP Overview SRP fairness algorithm Distributed algorithm Propagates and uses MAC usage info Source and forward rate controls Rapid adaptation and convergence Node 1 (1) (3) (5) (2) (4) Node 2 10

11 SRP Overview Scalable: Bit-rate; Circumference of ring; 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 /SDH framing 11

12 SRP Packet SRP is a media independent MAC layer protocol The initial implementations utilizes Byte Synchronous HDLC within /SDH framing (OC-12c, OC-48c, OC-192c) Allows transport via: Dark Fiber; /SDH; WDM Transport Overhead Path Overhead Payload F L A G MAC Header Payload F C S F L A G 12

13 Comparison 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 sensitive applications No support for isochronous traffic 13

14 Comparison 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 14

15 Summary Scalable packet ring technology Bit-rate; Number of Nodes; Ring Circumference High bandwidth efficiency Cost effectiveness Distributed fault tolerance LAN, MAN and WAN applications 15