1Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Change to Hello Protocol Three way handshake Carry both Source and Destination Instance When establishing use zero as Destination Instance Established when you’ve received a hello from neighbor and have responded with a hello containing the most recently received Src_Instance and the Dst_Instance Need Last Refresh flag in Ack

2Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Summary Refresh Carries a list of Message IDs to be refreshed Current spec allow >100 per 1500 byte message Can be used as refresh for previously acked Path and Resv messages

3Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Srefresh Addresses Source address is address of the sending node PHOP for Path Message Source Address of original Resv Message Resv message always sent to neighbor Options on addressing path messages Destination Next Hop if known

4Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Srefresh Mcast Issue Source / Destination Addresses in Srefresh Needed for multicast RPF check Note Multicast address is needed to differentiate between (S,G) and (*,G) Suggestion Include Source / Destination addresses with multicast refresh message ID Send Srefresh to the Lan Local Multicast address

5Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Srefresh Optimizations New C-Types for contents of Summary Message Variable length, one copy of flags and epoch Unicast version 4 bytes per Message ID Multicast version 12 bytes per message Source Addr, Dest Addr, Message ID

6Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Refresh Mechanisms Bundle Message Message ID Message ID Ack Message ID Nack (proposed) Message ID withdrawal Summary Refresh Summary Acknowledgement Piggybacking Helloes

7Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Hello Subset Necessary Elements Message ID (Summary) Ack or Piggyback Ack Hello Protocol Applicability Point to point links Shared media Unicast only

8Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Summary Refresh Protocol Mechanisms Message ID Summary Refresh Summary Ack Applicability Point to point Shared media unicast (Fixable for) Shared media multicast if all routers have summary refresh capability

9Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Further Redundancy Bundle Message Summary Refresh Message »Do we need both? »Note that neither Hello or summary refresh require Bundle Message

10Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Compromise Drop Bundle Message Drop both Hello proposals Get everything we need from Summary Refresh Compact high rate refresh State compression (partial)

11Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Compromise Bundled Message ID C-Type Cuts message by approx. two thirds Disambiguates Message ID in Summary Message Message ID in Summary Message Same as any Message ID An Acked summary message ID can be placed in another summary message

12Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Compromise >300 message Ids per summary message = >90,000 with two levels Compact enough to send frequently No need for Hello Protocol No hard state

13Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Sender Procedures Collect message Ids into a first level summary refresh When acked the message ID can be placed in a second level summary refresh Second level summary need not carry message ID and need not be acked Time_Values object permitted in summary refresh

14Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Dropping a Message ID Drop first level summary message ID from second level summary Send a new first level summary deleting the message ID to be timed out When acked go add message ID to second level summary

15Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Receiver Side Refresh Ack and save first level summary messages, set timersAck and save first level summary messages, set timers Reset timers on retransmission of first level summary or if Message ID listed in second level summaryReset timers on retransmission of first level summary or if Message ID listed in second level summary Timing out a summary stops refresh of all messages listed (unless listed in a higher numbered summary)Timing out a summary stops refresh of all messages listed (unless listed in a higher numbered summary)

16Traffic Eng. © 1999, Cisco Systems, Inc. Cisco Systems Receiver Side State Sync Periodically refresh all messages listed within time-out period of those messagesPeriodically refresh all messages listed within time-out period of those messages If refresh finds a missing message send Nack for that message and for it’s containing first level summaryIf refresh finds a missing message send Nack for that message and for it’s containing first level summary Nack any subsequent refreshes of either Message IDNack any subsequent refreshes of either Message ID