[112076] in North American Network Operators' Group
RE: Greedy Routing
daemon@ATHENA.MIT.EDU (Jake Mertel)
Wed Feb 18 18:40:24 2009
From: Jake Mertel <jake@nobistech.net>
To: Deepak Jain <deepak@ai.net>, "Valdis.Kletnieks@vt.edu"
<Valdis.Kletnieks@vt.edu>, Rod Beck <Rod.Beck@hiberniaatlantic.com>
Date: Wed, 18 Feb 2009 17:39:44 -0600
In-Reply-To: <D338D1613B32624285BB321A5CF3DB250C9E2A5A52@ginga.ai.net>
Cc: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
I had to laugh when reading... This is how I think someone who doesn't "get=
" how the Internet works may try to re-explain what a researcher explained =
to them about how metrics influence the flow of traffic in BGP path selecti=
on.
Regards,
Jake Mertel
Nobis Technology Group, L.L.C.
Web: http://www.nobistech.net/
Phone: (312) 281-5101 ext. 401
Fax: (808) 356-0417
Mail: 201 West Olive Street
Second Floor, Suite 2B
Bloomington, IL 61701
-----Original Message-----
From: Deepak Jain [mailto:deepak@ai.net]=20
Sent: Wednesday, February 18, 2009 5:01 PM
To: Valdis.Kletnieks@vt.edu; Rod Beck
Cc: nanog list
Subject: RE: Greedy Routing
>
> Maybe there's some critical insight in the paper that Physorg managed
> to totally not mention, I dunno.
I saw it the same way...
" As the researchers explain, some types of networks are not navigable. For=
instance, if the probability that two nodes are linked doesn't depend on t=
he metric distance between them, then such networks are difficult to naviga=
te, as there is no way to choose one node over another based on distance. B=
ut when there is a connection between the link existence probability and th=
e hidden distance between nodes, metric distances can help to navigate the =
network, i.e., such networks are "navigable.""
If your network doesn't calculate or use metrics or weights, or AS path len=
gths... then you are not able to
throw packets like fairy dust to their intended destination. Worse, if you =
use metrics unrelated to distance
(like link cost) you could actually send your packets the wrong way.
It's funny, but I think they said that their math shows that the Internet w=
orks to generally route packets
(to a shorter path) than other possible paths.
I'm sure that will come as a surprise to all of us.
Deepak Jain
AiNET
