> Few queries on transport protocol to be used within the SIP dialog: > > > * Is it acceptable to change the transport protocol (tcp, > udp,..) for a new request within a SIP dialog?
Yes; however if I recall correctly, this excludes CANCEL and non-2xx's ACK. > Assuming that the new request within the SIP dialog has size > more than 1300 bytes and need to use TCP as transport protocol? Yes; see above and RFC 3261 section 18.1.1. > * In case, if a SIP entity want to force UDP protocol to be > used always for all messages within a SIP dialog, should it > need to set the transport parameter in the Contact Header as > "UDP"? No; however this assumes that something doesn't indicate that another transport (such as TCP) can be used and the other side is willing/able to use it. It also assumes that the next hop is willing/able to fall back to UDP per RFC 3261 section 18.1.1 and you are not listing for another transport (i.e. in case they try it). > * Will it be possible to use UDP protocol only between 2 SIP > entities for all messages across dialogs? Yes; however this assumes that you don't have a fragmentation, size, or security reason which would require another transport. See above for more details. > Is there a possibility to negotiate this transport parameter > beforehand between 2 entities (via OPTIONS ?) ? >From an IETF SIP negotiation perspective, no. However from a service, >configuration, or proprietary perspective, the two devices might allow such >behavior. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
