From: "Sylvain Coutant" <sco@adviseo.fr>
To: 'Molle Bestefich' <molle.bestefich@gmail.com>,
'James Harper' <james.harper@bendigoit.com.au>
Cc: 'xen-devel' <xen-devel@lists.xensource.com>,
xen-users@lists.xensource.com
Subject: RE: Ethernet MTU
Date: Wed, 16 Aug 2006 13:05:25 +0200 [thread overview]
Message-ID: <00cd01c6c123$e0aa2160$2f00a8c0@ELTON> (raw)
In-Reply-To: <62b0912f0608160336s34f6cc9cu739ede8c45a4ab9f@mail.gmail.com>
> James Harper wrote:
> > 802.1q lives under IP.
>
> That's right.
>
> But the VLAN exposes a virtual interface.
> That virtual interface should automatically have an MTU size of the
> underlying interface minus 4 bytes (for the VLAN tag).
It should. It does not. It's usually not a problem as networking equipment handle frames up to 1520-1540 bytes without much trouble, at least equipments able to manage tagged frames.
> And then IP fragmentation, working on top of that virtual Ethernet
> interface, should perform fragmentation correctly.
IP fragmentation handling is for routers when they connect two networks with different mtu sizes. This is not the case here, the IP stack generates frames that are as large as the mtu makes it possible.
Spamming xen-devel with non-Xen related network education and RFCs was not my intent, I was just wondering about jumbo frames support into Xen networking layer ...
BR,
--
Sylvain
next prev parent reply other threads:[~2006-08-16 11:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-16 10:13 Ethernet MTU Sylvain Coutant
2006-08-16 10:18 ` [Xen-devel] " Molle Bestefich
2006-08-16 10:24 ` James Harper
2006-08-16 10:36 ` [Xen-devel] " Molle Bestefich
2006-08-16 11:05 ` Sylvain Coutant [this message]
2006-08-16 11:36 ` Molle Bestefich
2006-08-16 11:20 ` [Xen-devel] " James Harper
2006-08-16 11:58 ` Molle Bestefich
2006-08-16 10:19 ` James Harper
2006-08-16 10:28 ` [Xen-devel] " Molle Bestefich
2006-08-16 12:12 ` Adrian Chadd
2006-08-16 12:30 ` Sylvain Coutant
2006-08-16 14:14 ` Herbert Xu
2006-08-16 14:16 ` Sylvain Coutant
2006-08-17 0:15 ` Herbert Xu
[not found] ` <20060816120908.GC8597@nnx.com>
[not found] ` <20060816205306.GA15396@nnx.com>
2006-09-13 14:55 ` [Xen-users] " Daniele Palumbo
2006-09-14 18:12 ` [PATCH] netback vlan support [WAS: Re: [Xen-users] Ethernet MTU] Daniele Palumbo
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