Subject: [P2PSIP] RELOAD - AppAttach and Transport Connections

From: "Bless, Roland (TM)" <[email-masked]>
Date: Mon, 08 Dec 2014 13:28:23 +0100

Hi,

while implementing a SIP usage we found it difficult
to actually demultiplex between different transport
links when using (App)AttachReq/Rsp.

1.) The RELOAD RFC https://tools.ietf.org/html/rfc6940
    doesn't clearly describe whether it is possible
    to have several transport links per usage
    (i.e., Application-ID), which could be useful.

2.) In case that AttachReq and AppAttachReq are
    sent at the same time, the initiating node cannot
    easily distinguish which transport link/connection
    belongs to which request, other than using different
    ports for each request (not so NAT/FW friendly).

3.) One potential workaround is to have only one
    open AppAttachReq "per peer". However, if an
    AppAttachReq is directed to a Resource-ID,
    one doesn't know which peer (Node-ID) will actually
    sent back the AppAttachRsp. Moreover, the incoming
    transport links can only be distinguished by
    using different port numbers, since the node-ID
    is probably not known beforehand.

Any other ideas than using different ports?

Regards,
 Roland