AS path question.

Rettke, Brian Brian.Rettke at
Wed Nov 10 20:07:05 CST 2010

If it's not a private AS, and it is the one that I own, who cares? AS-Path is the best mandatory value that is completely within my control to manipulate, which explains its proliferation in the network. I'd rather do it myself than have to rely on someone else.

That being said, I've found that more vendors are manipulating local preference values themselves, but offer local preference and other attributes to be set upstream. Which now has shifted the de-facto standards of MED and AS-PATH to the back burner.


Brian A . Rettke
Network Engineer, CableONE Internet Services

-----Original Message-----
From: Scott Weeks [mailto:surfer at]
Sent: Wednesday, November 10, 2010 6:26 PM
To: nanog at
Subject: Re: AS path question.

--- jbates at wrote:
From: Jack Bates <jbates at>

On 11/10/2010 5:44 PM, Scott Weeks wrote:
> Do you think (or is there evidence) that very many ASs use maxas-limit type commands?  I have never used it and never had any problems...

: ...but just to be safe I added it to all my routers. I
: don't know where I came up with the magical 75 number,
: but it definitely seems reasonable that anything with
: 75+ ASNs in the path probably don't deserve to be in
: my table.

Why did that make you feel safe?  Other than a bug, and ignorance of BGP, what is unsafe about a lotta prepends?


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