Hi, RFC4168: Multihoming: An SCTP connection can be associated with multiple IP addresses on the same host. Data is always sent over one of the addresses, but if it becomes unreachable, data sent to one can migrate to a different address.
Please, consider the following scenario: Proxy A (Address 1, Address 2) <----- SCTP association -----> Proxy B (Address 3, Address 4) Address 1 ---- vlan a (PRIMARY PATH)------ Address 3 Address 2 ---- vlan b (ALTERNATIVE PATH)------ Address 4 When the PRIMARY PATH (vlan a) fails, SIP messages are sent using the ALTERNATIVE PATH (vlan b). RFC3261- Receiving requests: When the server transport receives a request over any transport, it MUST examine the value of the "sent-by" parameter in the top Via header field value. If the host portion of the "sent-by" parameter contains a domain name, or if it contains an IP address that differs from the packet source address, the server MUST add a "received" parameter to that Via header field value. This parameter MUST contain the source address from which the packet was received. This is to assist the server transport layer in sending the response, since it must be sent to the source IP address from which the request came. Question: Which IP address shall we include in the received parameter: Address 1 or Address 2? Following 3261 it should be "Address 2" RFC3261- Sending responses: (...) the response MUST be sent using the existing connection to the source of the original request that created the transaction, if that connection is still open. (...). If that connection is no longer open, the server SHOULD open a connection to the IP address in the "received" parameter Question: If the SCTP association is open, shall we forward the response to "Address 2" even though "Address 1" (PRIMARY PATH) may be recovered? If the SCTP association is no longer open, shall we open a new association towards "Address 2"? Cheers, -- Victor Pascual Ávila _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
