From: Rick Jones <rick.jones2@hp.com>
To: Patrick McHardy <kaber@trash.net>
Cc: Stephen Hemminger <shemminger@vyatta.com>,
"David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org
Subject: Re: [PATCH] vlan: propogate MTU changes
Date: Mon, 06 Oct 2008 15:50:50 -0700 [thread overview]
Message-ID: <48EA964A.6060503@hp.com> (raw)
In-Reply-To: <48EA9223.8090700@trash.net>
Patrick McHardy wrote:
> Stephen Hemminger wrote:
>
>> On Mon, 06 Oct 2008 18:02:39 +0200
>> Patrick McHardy <kaber@trash.net> wrote:
>>
>>> - the stack in fact doesn't require us to reduce the MTU of a VLAN
>>> device as long as its within the physically possible MTU.
>>
>>
>> I think it should call change_mtu so userspace gets notified about both
>> changes.
>
>
> 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?
If physical interface MTUs are going to be bouncing around and VLANs get
their MTUs changed then perhaps a VLAN needs both a desired and actual
MTU setting. The VLAN's interface would then be the minimum of the
desired and actual MTU. I suppose it isn't too unlike having both an
administrative (desired) and operational (actual) interface state.
rick jones
next prev parent reply other threads:[~2008-10-06 22:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-06 15:30 [PATCH] vlan: propogate MTU changes Stephen Hemminger
2008-10-06 16:02 ` Patrick McHardy
2008-10-06 17:54 ` Stephen Hemminger
2008-10-06 18:25 ` [PATCH] vlan: propogate MTU changes (v2) Stephen Hemminger
2008-10-06 18:45 ` Duyck, Alexander H
2008-10-06 19:20 ` Ben Hutchings
2008-10-06 22:53 ` Patrick McHardy
2008-10-06 22:33 ` [PATCH] vlan: propogate MTU changes Patrick McHardy
2008-10-06 22:50 ` Rick Jones [this message]
2008-10-06 23:02 ` Patrick McHardy
2008-10-06 23:04 ` Patrick McHardy
2008-10-06 23:18 ` Rick Jones
2008-10-06 23:33 ` Patrick McHardy
2008-10-07 23:05 ` David Miller
2008-10-08 11:53 ` Patrick McHardy
2008-10-06 20:14 ` Krzysztof Oledzki
2008-10-06 22:38 ` Patrick McHardy
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