On Dec 4, 2009, at 12:57 PM, Sudhanva Mudigere Narayana Gowda wrote: > Hi, > I have a query regarding sctp multihoming behavior. > > I have setup a multihomed association and this is my observation > > Host_A (IP a): Local single Homed endpoint > > Host_B (IP b(Primary), IP c(secondary)): Remote multiHomed endpoint > > During Heartbeat I see that even though the Heart beat req is to the secondary ip of Host_B, the Host_B uses its primary ip as source when sending back the Heartbeat Ack. > Ie Host_A (IP a) --------HEART_BEAT_REQ-----------> Host_B(IP c) > Host_A (IP a)<--------- HEART_BEAT_ACK---------- Host_B(IP b) I guess host B is choosing the source address based on the destination address. Host A must be able to handle this. > > also during data exchange I observed that even when the data is sent to the secondary ip of Host_B, the SACK is being sent back from the primary ip of Host_B. > Host_A (IP a) --------DATA_MSG-----------> Host_B(IP c) > Host_A (IP a)<--------- SACK------------------- Host_B(IP b) Same as above. > > Is this the expected behavior, shouldn’t the node use the same ip on which it received the data or Heart_beat_req on while sending back the responses(Heart_beat_ack or SACK). That would be good. But some stacks select the source address based on the destination address. However, A has to accept both. > Due to this behavior if the primary ip of an endpoint fails the association goes down as the node will not be able to transmit any Heartbeat_Req or Heartbeat_Ack. Yes. > > On Host_A I blocked the incoming packets which has Host_B(IP b) as source and I expected Host_B to retry using its secondary ip addr, but I observed that even the retries from Host_B uses its primary ip . > > Does this mean that an endpoint always uses its primary-ip while sending packets, but might receive packets on primary or secondary-ip? How an endpoint selects the source address is implementation specific. Best regards Michael > > Thanks > Sudhanva > _______________________________________________ > Ietf mailing list > Ietf@xxxxxxxx > https://www.ietf.org/mailman/listinfo/ietf _______________________________________________ Ietf mailing list Ietf@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf