Great, thanks for the pointers! I will look into it.
On Thu, 2005-01-12 at 09:41 +0530, Pravesh wrote: > Hi Dave, > > You can refer IETF draft 'draft-ietf-sip-outbound-01' for your reference. > Abstract of the draft is: > Session Initiation Protocol (SIP) allows proxy servers to initiate TCP > connections and send asynchronous UDP datagrams to User Agents in order to > deliver requests. However, many practical considerations, such as the > existence of firewalls and NATs, prevent servers from connecting to User > Agents in this way. Even when a proxy server can open a TCP connection to a > User Agent, most User Agents lack a certificate suitable to act as a TLS > server. This specification defines behaviors for User Agents, registrars and > proxy servers that allow requests to be delivered on existing connections > established by the User Agent. It also defines keep alive behaviors needed > to keep NAT bindings open and specifies the usage of multiple connections > for high availability systems. > > Regards, > Pravesh > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of David Stuart > Sent: Thursday, December 01, 2005 5:31 AM > To: [email protected] > Subject: [Sip-implementors] Question about NAT/FW and UDP > > Hello, > > I have noticed that some SIP User Agents are sending UDP keep-alive packets > in order to keep the pinhole on the NAT from closing. > > But because of the fact that most of these NATs are either port restricted > cone or, in the worst case, symmetric, it means you need to send the packets > to their intended destination (including the port number). > > So, I worry about these packets because I think that maybe the > implementation of the receiving side might not account for packets which are > essentially "garbage" (for instance, a phone might interpret this as a lost > packet and do silence suppression, or a video codec may try to conceal > packet loss etc).. > > Therefore I am wondering if any standards (or even best practices) exist for > the sending of such packets. > > > Dave > -- > David Stuart, SIPquest > Email: dave (at) sipquest (dot) com > Phone: 254-8886 x234 Web: http://www.sipquest.com/ > Address: 300 - 350 Terry Fox Drive, Kanata Ontario, K2K 2P5 > > > _______________________________________________ > Sip-implementors mailing list > [email protected] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > Dave -- David Stuart, SIPquest Email: dave (at) sipquest (dot) com Phone: 254-8886 x234 Web: http://www.sipquest.com/ Address: 300 - 350 Terry Fox Drive, Kanata Ontario, K2K 2P5 _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
