1. Jump to first page IP Switching and Gigabit Routers Shlomi Malki Nachman Cohen

2. Jump to first page 2 Topics n Motivation. n Gigabit Routers. n IP Switching: u flow classification. u implementation. u GSMP/IFMP. n Conclusion.

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6. 6 Gigabit Routers n Multigigabit Routers. n IP/ATM. n Cell Switch Router (CSR). n IP Switching. n NetStart GigaRouter.

7. Jump to first page 7 Getting Up to gigabitRouter n Average packet size on internet is 2000 bits. n Therefore must forward 500 Kpps per Gbps of traffic. n Replace shared bus by switch fabric. n Separate processor performs routing function and scales with number of peers. Not with bandwidth. n Increase forwarding performance with multiple parallel forwarding engines.

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9. 9 Gigabit Router Components n Line Card u Contains the physical layer components. n Switch Fabric u Used to interconnect the various components of the gigabit router.

10. Jump to first page 10 n Forwarding Engine u Inspects packets headers. u Determines to which outgoing line card they should be sent. u Rewrites the header. n Network Processor u Runs the routing protocols. u Compute the routing table. u Handle network management. Gigabit Router Components (1)

11. Jump to first page 11 ATM Overview n CELL Vs PACKET. n Segmentation & Reassemble. n Connection Oriented. n Virtual Channel, VCI. n Virtual Path, VPI. n Label Swapping.

12. Jump to first page 12 Switch Fabric n Offers much higher aggregate capacity then the conventional backplane bus. n Implementation: u crossbar. u ATM.

13. Jump to first page 13 Switch Fabric (1) n ATM advantage: u Standard H/W. u QoS. u Multicast. n ATM disadvantage: u Cell oriented. u Connection oriented.

14. Jump to first page 14 Forwarding Engine n Location within the router: u Physically separate component. u Integrated with either the line card or the network processor. n At IP Switching most data need no forwarding engine interference. Whereas routers always requires at least one forwarding engine.

15. Jump to first page 15 Design of the Forwarding Engine n As we already saw we must forward 500 kpps per Gbps of traffic. n Two approaches to achieve this rate: u the silicon forwarding engine. u High speed general purpose processor with destination address caching.

16. Jump to first page 16 Silicon Design n Design u Silicon hardware. n Memory u 16 byte for each IPv4 route table entry. u 250,000 routers. u TOTAL: 4 Mbytes. n Forwarding capability u memory accesses per route = 1+logN. u 10 ns SRAM. u 200 ns for full lookup. u TOTAL: 5 Mpps. ( enough for 10 Gbps )

17. Jump to first page 17 Processor with caching Design n Design u A 415 MHz general purpose processor with internal cache. u Internal cache: least recently used of 9000 IPv4 destination address. n Memory u Additional external memory of 8 Mbytes (holds the complete routing table). n Forwarding capability u 11 Mpps - all requests are at cache. u Multicast - handle by the full routing table.

18. Jump to first page 18 Design of the Forwarding Engine

19. Jump to first page 19 Forwarding engine - summarize n Sufficient to offer a simple, best- effort packets forwarding. n Additional functionality required of the next generation of routers (multicast, QoS differentiation, firewall filtering, etc.) n Needs to base the routing decision on more fields in the packets header.

20. Jump to first page 20 IP Switching n Can used any higher level IP functionality. n Uses the concept of a flow (a sequence of packets that are treated identically by possibly complex routing function). n Uses an ATM switch as the switch fabric.

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22. Jump to first page 22 ATM as Switch Fabric n The 3 approaches that uses ATM as Switch Fabric are: u IP/ATM. u Cell Switch Router (CSR). u IP Switching.

23. Jump to first page 23 ATM as Switch Fabric n Incoming flows are mapped onto ATM VC’s. u The IP Switch uses a protocol IFMP (RFC1953) to propagate the mapping between flow and VCI. u IP/ATM uses a pool of pre- established PVC’s. u CSR uses RSVP protocol (RFC1577)to propagate the mapping between flows and VCI’s.

24. Jump to first page 24 Flow Classification n Flow classification operation is to select those flows that are to be switched in the ATM switch and those that should be forwarded in the forwarding engine. n Long duration flows - ATM switch. n Multicast - ATM switch. n Short duration flows - Forwarding engine.

25. Jump to first page 25 Flow Classification (1) IP Switch Controller Port 0Port 1 Po rt C IP Switch Controller Port 0Port 1 Po rt C

26. Jump to first page 26 Flow Classification (2) n For the flows selected for switching, a VC must be established. n IP Switching requires a protocol to distribute the association of flow and VCI label. n The task of cache lookup and packet labeling is propagated upstream to the edge of the network.

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28. Jump to first page 28 Flow Classification - summery n IP switch provides high speed routing by low level switching of flows. n It defines protocol to indicate these flows. n All flows are classified. n The forwarding engine is optimized for flow classification and for forwarding uncached packets.

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30. Jump to first page 30 Forwarding by the IP Switch Default IP Switch Controller Default IP Switch Controller Default IP Switch Upstream direction Downstream direction SourceDestination

31. Jump to first page 31 IP Switch Controller Forwarding by the IP Switch Default Port 0Port 1 Default Upstream direction Downstream direction IFMP Redirect (Flow ID,VPI/VCI=A,lifetime) VPI/VCI=A Port C z

32. Jump to first page 32 IP Switch Controller Forwarding by the IP Switch Port 0Port 1 Default Upstream direction Downstream direction IFMP Redirect (Flow ID,VPI/VCI=A,lifetime) VPI/VCI=A Port C Default VPI/VCI=B IFMP Redirect (Flow ID,VPI/VCI=B,lifetime)

33. Jump to first page 33 General Switch Management Protocol (GSMP) n Simple master-slave protocol. u Switch controller - master. u ATM switch - slave. n Unreliable massage transport is assumed between controller and switch for speed and simplicity. n GSMP runs on a single well known virtual channel (VPI 0,VCI 15).

34. Jump to first page 34 GSMP (1) n The most frequent messages (connection management) are small enough to be a single cell. VerTypeResultCode Transaction Identifier GSMP Message Body Pad (0-47 octets) GSMP Message Format

35. Jump to first page 35 GSMP (2) n An adjacency protocol is used to: u Synchronize state across the control link. u Discover the identity of the entity of the far end of the link. u Detect when the far end is changed. n No GSMP massages may be sent across the link until adjacency has been established.

36. Jump to first page 36 GSMP (3) n GSMP has five type of massages: u Configuration. u Connection management. u Port management. u Statistics. u Events.

37. Jump to first page 37 Ipsilon Flow Management Protocol (IFMP) n Runs on a point to point link between two IP switches. n The purpose of IFMP is to inform the transmitting end of a link of the VCI that should be associated with a particular IP flow. n The VCI is selected by the receiving end of the link.

38. Jump to first page 38 IFMP (1) n Two flow types has been defined: u port-pair flow (type 1) - source IP address,destination IP address,source port number,destination port number. u Host-pair flow (type 2) - source IP address,destination IP address. n An IFMP redirect message is sent upstream to inform the transmitter of the association between flow and VCI.

39. Jump to first page 39 IFMP (2) VerIHLTOSTTL Source IP Address Protocol Destination IP Address Source PortDestination Port Flow type 1 - Identifier VerIHLRsrvdTTL Source IP Address Rsrvd Destination IP Address Flow type 2 - identifier IFMP Redirect MSG Flow Type Label Flow Identifier Flow IDLifetime

40. Jump to first page 40 IFMP (3) n A lifetime field specified the length of time for witch this association of flow and VCI is valid. n The flow redirection must be refreshed. n Flow labeling process occurs independently an concurrently on each link. n The flow classification policy is consistent within an administrative domain.

41. Jump to first page 41 IFMP (4) n When upstream and downstream links are both labeled for a given flow, that flow is switched directly trough the ATM switch. n When an IP switch accepts a redirection messages it also change the encapsulation. n It allows an IP switch to act as a simple based firewall.

42. Jump to first page 42 Conclusion n The IP switch is an alternative architecture to the gigabit router. n It uses low level switching of flows. n It include a cooperative protocols. n Link by link basis decision. n All flows are classified. n It allows to support multicast, QoS, Simple firewall filtering.