The challenge before Speermint and Drinks – moving beyond full mesh into open interconnection
Friday, August 14th, 2009Otmar Lendl recently posted a thoughtful piece called “What’s wrong with Speermint and Drinks” that digs into the differences between and the challenges of the IETF’s Speermint and Drinks Working Groups. Otmar started out explaining why they are necessary:
First of all, why do we need these WGs at all? The quick answer is that VoIP interconnection based on plain SIP and ENUM did not work out as envisioned by the authors of the respective RFCs. There are a number of reasons for that (see draft-lendl-speermint-background), and I don’t expect that the IETF can do anything to change this.
He then points out the fundamental problem facing these groups and really the “SIP/VoIP space” in general:
Call routing was rather simple in the full mesh world (be it PSTN or RFC3263 SIP), it only needed some directory service to map Public Identities (PI = phone numbers or SIP URIs) to operators. In a lot of cases, these directories are static simple mappings like “route anything starting with +49 to Deutsche Telekom”.
This is no longer sufficient. Any solution to the current world-wide call routing problem needs to cope with arbitrary interconnection graphs, not just the trivial case of full meshes. A directory will not suffice any more: we need a full blown routing algorithm.
I repeat: The current graph of interconnection between carriers has no special properties any more. We have a text-book routing problem to solve.
That is the challenge. The old world of the PSTN was relatively simple. Fewer players in the interconnection game… and because there were so few they could do “full mesh” interconnectivity between the various players.
It’s a different world, today. There are many players in the call routing game and pretty much anyone can enter that game. Otmar’s point is that the current proposed solutions focus more on central registries and other mechanisms traditionally used in the world of the PSTN. He argues that we really need more of a “routing” solution that allows multiple registries and systems – and indeed works like other Internet routing protocols.
For those interested in the underlying SIP plumbing that is being built to better interconnect all of us using SIP out there, Otmar’s post is well worth a read (fair warning that it does dive into details and terminology).
I don’t know that there are any easy answers out there (or it would have been solved already)… but the conversation is ongoing and will continue for quite some time.
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