[155935] in North American Network Operators' Group
Re: MTU mismatch on one link
daemon@ATHENA.MIT.EDU (Mike A)
Fri Aug 31 10:03:46 2012
Date: Fri, 31 Aug 2012 09:03:03 -0500
From: Mike A <mikea@mikea.ath.cx>
To: NANOG list <nanog@nanog.org>
In-Reply-To: <6E5736BD68F770449C74FBAD975F807C8E1D2BBE@NYDC-EXCH01.vinci-consulting-corp.local>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Fri, Aug 31, 2012 at 01:52:09PM +0000, Paul Vinciguerra wrote:
> You need to raise your MTU above that on the other side and do a ping size sweep. Unlike at Layer-3 when you can use set a DF bit and get back an ICMP error, at Layer-2 when you exceed the far side's MTU, the packets are silently dropped.
>
In the past, I've found a binary search on ping size to be very
efficient. YMMV, of course.
--
Mike Andrews, W5EGO
mikea@mikea.ath.cx
Tired old sysadmin
