Subject: [straw] I-D on RTP failover problem

From: Martin Taylor <[email-masked]>
Date: Fri, 4 Mar 2016 14:47:52 +0000

I recently posted https://tools.ietf.org/id/draft-taylor-mmusic-rtp-failover-problem-00.txt  This offers a problem statement around RTP failover.  The TL;DR summary:

- VoIP networks typically contain network functions that terminate large numbers of RTP streams, such as session border controllers and conference bridges.

- Service providers typically require that such network functions have no single points of failure that could cause large numbers of media streams to be interrupted for more than a second or two.

- The usual solution for this is to deploy such network functions as an active / standby pair with a service IP address that can be moved between members of the pair, for example with the aid of a gratuitous ARP, in a manner analogous to VRRP.

- This solution suffers from a number of drawbacks including inefficient use of hardware resources and inability to deploy in environments where it is impractical to connect active and standby instances to the same L2 segment.  These drawbacks are causing network operators particular concern in network function virtualization environments.

We were planning to propose a solution to this problem that would likely involve some extensions to SDP to communicate a connection address for an alternative backup media path, but at this point we are looking for a consensus that this is a worthwhile problem to address.

So far, this I-D has not generated any reactions on the mmusic or avtcore mailing lists.  I realize that straw is primarily focused on SIP traversal issues, but it occurs to me that many of the contributors to straw have an interest in real-world issues around session border controllers, and this certainly falls into that category.

Martin