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Label scalability of Carrier Ethernet

Label scalability of Carrier Ethernet. Benchmarking Carrier Ethernet Technologies Workshop Session AI.2 - Scientific and Technical Results EuroNGI 2008, Krakow, Poland April 30, 2008 Wouter Tavernier, Koen Casier (Ghent University – IBBT) Luis Caro (University of Girona)

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Label scalability of Carrier Ethernet

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  1. Label scalability of Carrier Ethernet Benchmarking Carrier Ethernet Technologies Workshop Session AI.2 - Scientific and Technical Results EuroNGI 2008, Krakow, Poland April 30, 2008 Wouter Tavernier, Koen Casier (Ghent University – IBBT) Luis Caro (University of Girona) Dimitri Papadimitriou (Alcatel-Lucent Bell NV) Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  2. Agenda • PROBLEM STATEMENT • Labels in Carrier Ethernet • Label scalability • Label optimization • Results • Short word on label lookups • Conclusion Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  3. Problem statement • Evolution of Ethernet being a LAN technology towards a Carrier Technology • Ethernet = low cost • Ethernet = ubiquitous • Ethernet = plug & play • LAN environments: traffic streams between tens of end-users • Metro/Access environments: traffic streams between thousands of end-users • PROBLEM STATEMENT: • Is Carrier Ethernet able to cope with increasing number of traffic streams Metro network LAN L Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  4. Sync SD DA SA EthType Payload 7 1 6 6 2 46 - 1500 ZC ZC ZC ZC ZC No labels in bridged Ethernet • Forwarding in native Ethernet bridging : stateless (CL) 48 bit MAC-address based A X 1 1 2 5 4 2 3 3 B Y DestOut Port B 2 X 5 Z 5 C 3 DestOut Port X 1 Z 3 A 4 C Z Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  5. Labell Labell Labels in Carrier Ethernet • The concept of a connection (LSP) allows for (CO): • Traffic Engineering • Advanced recovery/protection techniques • BW guarantees • Forwarding is based on a label linked to the connection state Two connections (LSPs) from A to E: maintains state for the green and red connection and forwards based on a label Two connections (LSPs) from A to E D E A B C Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  6. E,200 E,200 E,200 Domain-wide PBB-TE label • Ingress A has 2 LSPs to E, for e.g.: • Protection switching • Load balancing Label remains constant along connection (no SWAP)! Label remains constant along connection (no SWAP)! D E A <100, A> <200, E> <100, E> Distinct routes for dest E, by diff B-VID. B C B-VID 100 reused on same link Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  7. 100 200 100 Link local ELS label • Ingress A has 2 LSPs to E, for e.g.: • Protection switching • Load balancing Label remains constant along connection (no SWAP)! Label can be swapped in intermediate hops along connection! D E A B-VID 100 reused on same link S-VID 100 reused on other link Distinct routes for dest E, by diff S-VID. B C Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  8. . . . x incoming Label usage optimization • Label balancing (online routing optimized ELS) • Shortest path routing takes into account labels used on a link as cost • Merging (ELS) • 1 incoming label per interface + 1 outgoing label • GAIN: x-1 labels on outgoing local interface • Shared forwarding (PBB-TE) • 1 label needed • GAIN: x-1 global labels Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  9. Label scalability • Given the label: • How do different label schemes react under changing conditions? • What is the influence of the topology? • What is the influence the traffic matrix? • What is the influence of the traffic matrix on typical BW usage? ELS PBB-TE Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  10. x B ii A i 1 C 2 b L a ii i 10 3 D 4-9 E Study assumptions • Study the impact on label usage of the following dimensions: • Topology (CONNECTEDNESS) • Traffic matrix (SIZE, UNIFORMITY) • BW usage • NORMALIZATION: • Tests have run 100 times • Only one dimension has been changed in a time • Shortest Path Routing (Dijkstra hop count) is taken as base routing algorithm • Base topology of 100 nodes (connectedness +-2) & 1000 demands L Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  11. Connectedness of a network • Connectedness of a topology: what is the average node degree of a node in a topology: ring vs. full mesh • Example: • Single (un-)connected • 4-connected • Full mesh Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  12. Connectedness of the topology S Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  13. Connectedness vs BW (Luis) • The topology generator considered for generating the topologies in this section is IGEN • For all the topologies the link capacity is set to 10Gb/s and bandwidth request of 100Mb, 200Mb and 300Mb are generated until the network is overloaded. • The implemented algorithm is the SPF • Overload network with links of 10G capacity A Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  14. Connectedness vs. BW (Luis) Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  15. Connectedness vs. BW (Luis) Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  16. Topology size vs. BW (Luis) Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  17. Topology size vs. BW (Luis) Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  18. Uniformity of the traffic matrix • UNIFORMITY: X demands directed to 1 vs. x destinations? • Example: • 4 demands • 2 destinations vs 4 destinations 4 paths / 1 dest 4 paths / 2 dest 4 paths / 4 dest Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  19. Uniformity of the traffic matrix S Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  20. Size of the traffic matrix • The size of a traffic matrix affects the number of demands that are routed over a network: • 10 demands • 100 demands • 1000 demands • 10000 demands • … Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  21. Scaling the order of the traffic S Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  22. Lookup mechanism must be simple and easy to implement • Memory access time is the bottleneck 200Mpps × 2 lookups/pkt = 400 Mlookups/sec → 2.5ns per lookup Lookups Must be Fast Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  23. Direct Memory Lookup (Outgoing Port, new SVID label) SVID/MPLS-label Memory Data Address Direct lookup in ELS vs PBB-TE • PBB-TE: • Label space is 48+12 bits • With 64b data, this is 64 EiB of memory (2^60). • Label space is global • 2^60 > 2^12, therefore cannot hold all addresses in table and use direct lookup, less efficient alternatives: • Hashing • Binary/Multi-way Search Trie/Tree • ELS: • Label space is 12 bits • With 64b data, this is 256 K of memory. • Label space is private to one link • Therefore, table size can be “negotiated” Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  24. Conclusion • The specific traffic matrix & topology used, clearly affect label usage • The uniformity of the traffic matrix affects PBB-TE-type domain-wide labelling: more uniform is better • The topology connectedness affects ELS-type link-local labelling: more connected is better • In typical metro-network with low node-degree, PBB-TE & ELS LL have similar performance • PBB-TE with SF and ELS with merging consistently score better than alternatives • Node local labelling techniques consistently score worse than alternatives. • The label length affects the memory space needed and accordingly affects cost and lookup speed Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  25. Appendices Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  26. Carrier-Grade Ethernet challenges • Flat address space  scalability of number of MAC addresses to be learned • Beyond 100k learned addresses per node seems challenging • Scalability in terms of number of VLANs • 12-bit VLAN ID (VID): 4k VLANs possible network wide • STP cannot converge faster than worst case 20s sec (root failure) • Traffic Engineering (routing) constraint by tree based structure. • Limited OA&M Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  27. x B ii A i 1 C 2 b L a ii i 10 3 D 4-9 E Reference network Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  28. Assumptions (Luis) • Results are evaluated in terms of the maximum and average number of: • For ELS (average calculated based on the number of links): • Labels per link • Labels per link with agg (meaning only paths are count) • Labels per link with agg and label merging • For PBB-TE • Labels per destination • Labels per destination with agg (meaning only paths are count) • Labels per destination with VLAN-reut (meaning link disjoint paths can use same label) • Labels per destination with INV-trees (paths that intersect only on a common segment ending at the destination can also use the same label) B Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  29. Tests on smaller networks not normalized Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  30. Uniformity in small 3-connected network S Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  31. Connectedness in 28n network S Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

  32. Traffic scaling in small network S Label scalability & efficiency of Carrier Ethernet – Wouter Tavernier Vakgroep Informatietechnologie – Onderzoeksgroep IBCN

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