Re: [RRG] Re: [RAM] Tunneling overheads and fragmentation

Dino Farinacci <dino@cisco.com> Thu, 13 September 2007 01:58 UTC

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From: Dino Farinacci <dino@cisco.com>
Subject: Re: [RRG] Re: [RAM] Tunneling overheads and fragmentation
Date: Wed, 12 Sep 2007 18:58:18 -0700
To: Gert Doering <gert@Space.Net>
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> So there is no way our network could run on a MTU of 4470 or even
> higher any time soon.

Then you don't deploy ITRs or you deploy fragmenting-ITRs.

> [..]
>>    In practice, this is not really a problem.  Hosts typically do not
>>    originate IP packets larger than 1500 bytes.  And second, a survey
>>    has been taken (from a list of ISPs, see Acknowledgement section)
>>    where nearly all ISP link MTUs are either 4470 bytes or support
>>    Ethernet jumbo frames of 9000 bytes.  Therefore, we don't  
>> anticipate
>>    any problems with prepending additional headers.
>
> This is handwaving, and not a good basis for research work.

You are right, we are trying to make a decision and are doing  
engineering now past the research stage.   ;-)

Dino



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