From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: [PATCH] vlan: propogate MTU changes Date: Mon, 06 Oct 2008 16:18:36 -0700 Message-ID: <48EA9CCC.2050505@hp.com> References: <20081006173024.2741cc01@speedy> <48EA369F.3090306@trash.net> <20081006195446.1dc5a372@speedy> <48EA9223.8090700@trash.net> <48EA964A.6060503@hp.com> <48EA98F0.40302@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Stephen Hemminger , "David S. Miller" , netdev@vger.kernel.org To: Patrick McHardy Return-path: Received: from g5t0007.atlanta.hp.com ([15.192.0.44]:23308 "EHLO g5t0007.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752970AbYJFXTg (ORCPT ); Mon, 6 Oct 2008 19:19:36 -0400 In-Reply-To: <48EA98F0.40302@trash.net> Sender: netdev-owner@vger.kernel.org List-ID: Patrick McHardy wrote: > Rick Jones wrote: > >> Patrick McHardy wrote: >> >>> Agreed. But the question when to do automatic adjustments remains. >> >> >> A matter of interpretation of the principle of least surprise right? >> Which is less surprising - that a VLAN's MTU drops to match that of >> the physical interface or that some traffic on the VLAN stops when the >> physical interface's MTU drops? > > > The traffic actually shouldn't stop since the MTU isn't enforced by > the lower layers and also usually not by the driver. So I feel unable > to make a policy decision when both views don't seem unreasonable. > Especially given the fact that the "more suprising" behaviour so far > has been our default. Does changing the MTU on a physical interface not change the size frame the NIC itself will be willing to accept? rick jones