[114072] in North American Network Operators' Group
RE: Important New Requirement for IPv4 Requests
daemon@ATHENA.MIT.EDU (Justin Horstman)
Thu Apr 30 11:25:13 2009
From: Justin Horstman <jhorstman@adknowledge.com>
To: "Robert E. Seastrom" <rs@seastrom.com>, Randy Bush <randy@psg.com>
Date: Thu, 30 Apr 2009 10:25:06 -0500
In-Reply-To: <863abqwdas.fsf@seastrom.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Default MSS for most linux is 0, which causes the kernel to calculate it as=
the interface MTU-40bytes. You can either change the MTU on the interface =
or more specifically use the 'ip route <ipblock> dev <interface> advmss <ne=
w mss>' command to update it on a per route basis.
~J
-----Original Message-----
From: Robert E. Seastrom [mailto:rs@seastrom.com]=20
Sent: Thursday, April 30, 2009 7:12 AM
To: Randy Bush
Cc: nanog@nanog.org
Subject: Re: Important New Requirement for IPv4 Requests
Randy Bush <randy@psg.com> writes:
> mtu clue is also useful. here on tokyo b-flets, and i would guess in
> many other ppoe environments, you need to tune or lose big-time.
But not difficult to beneficially MiM:
in pf:
scrub in on gre0 max-mss 1400
scrub out on gre0 max-mss 1400
in cisco-land:
ip tcp adjust-mss 1400
i'm sure the linux folks can offer up something similar...
-r
