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Date: Tue, 10 Aug 2004 12:41:49 +0900
From: Alexander Nedotsukov <bland@FreeBSD.org>
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To: Doug Rabson <dfr@nlsystems.com>
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cc: freebsd-firewire@FreeBSD.org
Subject: Re: max MTU for fwip device.
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Doug Rabson wrote:

>On Monday 09 August 2004 04:06, Alexander Nedotsukov wrote:
>  
>
>>Hi again,
>>Is there any reason why we do not support MTUs higher than 1500 bytes
>>on firewire links?
>>    
>>
>
>Basically, we are limited by the specification. The rfc states that the 
>default MTU should be 1500 bytes. From the spec: "NOTE: IP-capable 
>nodes may operate with an MTU size larger than the default, but the 
>means by which a larger MTU is configured are beyond the scope of this 
>document."
>  
>
Well standards are good. But I don't see any restriction here. In fact I 
belive that effective MTU should be evaluated from maximum payload table 
(RFC2734 Table 1) and ieee1394 header size. Anyway this 1500 which comes 
from 10Mbit ethernet land may be good for default but manual 
configuration should not be prohibited.

Btw default MTU size on MacOSX for fw? interface is 2030 which is 10 
bytes less that theoretical maximum for S400 async stream.

All the best,
Alexander.