Greedy Routing

Valdis.Kletnieks at Valdis.Kletnieks at
Wed Feb 18 22:35:15 UTC 2009

On Wed, 18 Feb 2009 22:12:02 GMT, Rod Beck said:

>From the fine article:

"In greedy routing, a node passes information to the neighboring node that is
closest to the final destination in an abstract space called hidden metric

Sounds suspiciously like "throw the packet at the router that's got the shortest
AS path to the destination" doesn't it?  You don't need to know the entire
topology to know router X is 2 AS's closer to the dest than router Y once
X and Y have been loaded with the "hidden metric space" known as a BGP update ;)

I'm not sure this article is actually telling us anything we didn't already
know. Now if there was a way to compute those distance metrics without
global knowledge - if there was only an algorithm that
only cared about what was "upstream" from a locally connected link and whether
it was connected.  Say, we could call it a link-state routing protocol....

Now if they were able to actually develop a link-state protocol that involved
*only* local adjacency announcements and not flooded announcements, *that*
would be something...  But what I see here is "if somebody developed that,
we'd be able to route more efficiently".

Maybe there's some critical insight in the paper that Physorg managed to
totally not mention, I dunno.
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