Re: [RAM] Tunnelling & GigE jumbo frame size

RJ Atkinson <rja@extremenetworks.com> Wed, 12 September 2007 20:07 UTC

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From: RJ Atkinson <rja@extremenetworks.com>
Subject: Re: [RAM] Tunnelling & GigE jumbo frame size
Date: Wed, 12 Sep 2007 16:07:41 -0400
To: Gert Doering <gert@space.net>
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On  12 Sep 2007, at 16:02, Gert Doering wrote:
> On Wed, Sep 12, 2007 at 12:47:58PM -0700, Dino Farinacci wrote:
>> To summarize the issue we are trying to put to rest:
>>
>> o All router-to-router links on the downstream side of an ITR use
>> either 4470 or 9180 byte MTUs.
>
> Where is this assumption coming from?
> As long as there are FastE links, this is not going to happen.

Are you trying to say that you currently have deployed
router-to-router links inside an ISP/IX with less than
4470 bytes of IP MTU ?

Btw, at least some 100baseTX/FX switches/routers can
support the 9180 IP MTU.  So it is not necessarily
the case that 100baseTX/FX implies a 1518 byte link MTU.

Ran


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