1. Smart IP Switching A Hybrid System for Fast IP-based Network Backbones David Lloyd Donal O’Mahony

2. IP over ATM uConventional IP routers have become a bandwidth bottleneck uATM technology offers high bandwidth capability uIP over ATM schemes have been developed to support IP over and ATM Network Classical IP over ATM Next Hop Resolution Protocol (NHRP) LAN Emulation (LANE) Multi-Protocol Over ATM (MPOA)

3. Heavyweight Nature of Emulation Techniques ATM Network Emulation Scheme IP Network Overlay Model

4. IP on ATM Hardware uIP implemented directly on ATM hardware uSchemes may be categorised by the approach they employ for setting up switched paths through a network uPrincipal Approaches are: Traffic-Driven - Nature of traffic drives switch path establishment - (Ipsilon’s IP Switching and Toshiba’s CSR) Control-Driven - Switched paths set up before data traffic flows - (Cisco’s Tag Switching and IBM’s ARIS)

5. Traffic-Driven Approaches Advantages uSwitched paths are only set up for long-lived flows uSchemes are non-complex uResilient in event of failure uScalable Disadvantages uFlow aggregation is not an inherent property of the scheme uShort-lived Flows that recur consistently can cause excessive control traffic

6. Flow Merging in Control-driven Schemes VC Merge uThe merging of one or more incoming VCs into the same outgoing VC uRequires special VC merge-capable ATM hardware VP Merge uThe merging of one or more incoming Virtual Paths (VPs) onto the same outgoing VP uIt is imperative to ensure that active VCs are not merged uBlock allocation of VCIs Required

7. AAL-5 Cell Interleave

8. Control-Driven Approaches Advantages uNo delay in setting up a dedicated VC on a flow by flow basis uAll IP packets are switched at layer 2 Disadvantages uDedicated-VCs are established for all routes uSchemes are Complex

9. Multi-Protocol Label Switching In early 1997 the IETF Multi-Protocol Label Switching (MPLS) working group was established. The group issued a framework document, which attempts to: uProvide a coherent description of the major approaches uDiscuss the technical issues involved uLay the way forward for standardisation

10. Introduction to Smart IP Switching Smart IP Switching is a new traffic-driven scheme that exhibits advantages of both the traffic-driven and control-driven approaches. The main benefits of Smart IP Switching are: uThe Introduction of flow aggregation into a traffic-driven scheme uThe definition of short-term and long-term VCs uIncreasing the proportion of IP packets switched at layer 2

11. Smart IP Switching Concepts The key concepts that define Smart IP Switching are: uUnique Flow Identifier - Flow Identification uFlow aggregation - Based on CIDR prefixes uIngress-piping - Merging flows at an ingress node uVirtual Merge - Merging flows at intermediate nodes uLongevity of VCs - short-term and long term VCs

12. Flow Identification uThe Unique Flow Identifier identifies Ipsilon flow types plus a new flow type (flow type 3) uFlow type 3 is specifically defined to represent aggregate flows

13. Smart IP Switch Representation

14. Smart IP Switch Operation (1) SIPS Operation (First Packet) SIPS Operation (Dedicated VCs) VPI=0 VCI=32 Default VC SIPS1 SIPS3 SIPS2 LAN1 Default VC first packet IFMP REDIRECT first packet P1 P2 P1 P2 P1 P2 P1=port 1 P2=port 2 Default VC Ingress-pipe

15. Smart IP Switch Operation (2) SIPS Operation (Second packet) SIPS Operation (First Cut-through) VPI=0 VCI=32 Default VC SIPS1 SIPS3 SIPS2 LAN1 second packet P2 P1 second packet Ingress-pipe Cut-through Default VC Down-piping

16. Smart IP Switching Operation (3) SIPS Operation (Second Cut-through) VPI=0 VCI=32 Default VC SIPS1 SIPS3 SIPS2 LAN1 P2 P1 second packet VCI=33 Ingress-pipe Cut-through

17. Ingress-pipe at Intermediate Node SIPS Operation (Intermediate Ingress-Pipe) VPI=0 VCI=32 Default VC SIPS1 SIPS3 SIPS2 LAN1 P2 P1 VCI=33 FDDI : LAN VCI=35 Ingress-pipe P1=port 1 P2=port 2 Cut-through

18. Virtual Merge SIPS Operation (Virtual Merge) SIPS1 SIPS3 SIPS2 LAN1 P1 P2 P1 P2 P1=port 1 P2=port 2 egress node Dedicated VC next available VC ingress node ingress-pipe SIPS4 P2 P1 LAN2 virtual merge ingress-pipe Dedicated VC default VCs omitted for clarity

19. Ingress-Piping SIPS1 10/100 Mb Ethernet links 10 Mb Ethernet LAN network :172.16.0.0 SIPS3 SIPS4 SIPS2 LAN3 LAN1 LAN2

20. Flow Management uFlow Information Base (FIB) used to manage flows uIpsilon flow types are created and refreshed as normal uDetection of a potential aggregate flow is based existence of a CIDR prefix uFlow type 3 is refreshed by sending an REDIRECT message with a redirect message element attached for every upstream ingress-pipe that remains active uReferesh of VCs is managed on a localised scope

21. Longevity of VCs uThe first time a flow is detected, it is set up as short-term uA VC used by many flows is transitioned to long-term uVCs for flows that recur are set up as long-term uLong-term VCs do not have to be refreshed as often as short-term VCs

22. VC Pool uThe use of a VC pool eliminates the delay incurred in setting up a VC uA suitable strategy to manage VC pool size must be employed uVCs may be expensive uPackets arriving on an unassigned VC must be associated with the relevant flow type 3 uThe use of a VC pool has been discussed in the literature

23. CIDR Fall-back VPI=0 VCI=32 Default VC SIPS1SIPS3 SIPS2 LAN1 P2 P1 Host: 172.16.3.1 Network: 172.16.3.0 Routing table entry 172.16.3.0 Routing table entry 172.16.0.0 Routing table entry 172.16.0.0 Based on UFI prefix 172.16.0.0 Based on UFI prefix 172.16.3.0

24. CIDR-Fall-back (2) VPI=0 VCI=32 Default VC SIPS1SIPS3 SIPS2 LAN1 P2 P1 Host: 172.16.3.1 Network: 172.16.3.0 Routing table entry 172.16.3.0 Routing table entry 172.16.0.0 Routing table entry 172.16.0.0 VCI=33 Based on UFI prefix 172.16.3.0 Based on UFI prefix 172.16.3.0

25. Simulated Network

26. Simulation Results

27. Summary Smart IP Switching: uIs a new traffic-driven IP on ATM hardware scheme modelled on Ipsilon’s IP Switching uIntroduces Flow Aggregation into the traffic driven-scheme uIntroduces the concept of short-term and long-term VCs uSignificantly increases the proportion of IP Packet that are diverted from being forwarded (layer 3) to being switched (layer 2) - A performance level that is comparable to that of the control-driven approaches, while retaining the simplicity, scalability and reliability of the traffic-driven approach