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RE: [Xen-users] Changing MTU of vif

To: "Phillip Bennett" <phillip@xxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] Changing MTU of vif
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Wed, 26 Mar 2008 22:35:50 +1100
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Thread-topic: [Xen-users] Changing MTU of vif
I've been vaguely following this discussion, and AFAIK, xen does not
provide a mechanism to keep the backend and frontend MTU's in sync.

You'd need a xenstore settings in the frontend and the backend, eg the
backend would specify a minimum possible MTU and a maximum possible MTU,
and the frontend would specify the MTU it uses.

Minimum and maximum MTU would be specified at domain configuration time
(defaulting to 1500/1500 probably). The backend would set it's interface
to the value the frontend specifies, eg:

Backend:
 backend/vif/<id>/<vif>/min-MTU = 576
 backend/vif/<id>/<vif>/max-MTU = 1500

Frontend
 Device/vif/<vif>/MTU = 1500

Possibly it would only be legal to change the MTU value while the
interface was not in the "connected" state...

Does anyone know if, on a linux bridge, there is any reason why all
attached devices wouldn't have the same MTU?

James


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