Subject: Re: IPv6 addresses really are scarce after all

From: Jun-ichiro itojun Hagino <[email-masked]>
Date: Wed, 22 Aug 2007 11:54:10 +0900

>> 	that's true, but when link MTU is different, it gets very nasty.
>
>IEEE 802 standards do not permit variation in the link MTU
>for Ethernet.  Attempts to persuade IEEE 802 to approve use
>of jumbo-MTUs (e.g. 9180 bytes + Ethernet framing) have
>consistently failed within the IEEE 802.

	ok, then pls think about FDDI-to-ethernet bridge (i guess it is also
	spec conformant but there are products), and/or 802.11 bridges.

itojun

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From: [email-masked] (Jun-ichiro itojun Hagino)
Date: Wed, 22 Aug 2007 11:59:21 +0900 (JST)

> 	spec conformant but there are products), and/or 802.11 bridges.

	non-conformant, of course :-)

itojun

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From: Iljitsch van Beijnum <[email-masked]>
Date: Wed, 22 Aug 2007 12:02:16 +0200

>> consistently failed within the IEEE 802.

This is strange, I never got the original message.

So I'm not sure why this point was brought up, but let me jump in and  
point to my draft:

http://www.ietf.org/internet-drafts/draft-van-beijnum-multi-mtu-00.txt

We've had some discussions on the internet area mailinglist and I'm  
hopeful that it will be possible to standardize a mechanism to make  
nodes with different MTUs live on the same subnet and use the maximum  
packet size supported by both neighbors rather than all nodes  
conforming to the MTU of the least capable system.

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From: Russ Housley <[email-masked]>
Date: Tue, 28 Aug 2007 14:36:15 -0400

Ran:

See section 7.1.2 of IEEE Std 802.11-1999.  Figure 12 shows the MAC 
Frame format, and the payload can be up to 2312 octets.  However, you 
need to consider the whole system.  On the wired side, most Access 
Points will be connected to Ethernet, which becomes the point that 
limits the MTU seen by any wireless station.

Russ

At 11:09 PM 8/21/2007, RJ Atkinson wrote:
>My understanding is that 802.11 has no difference
>in Link MTU size from 802.3.  If someone thinks that
>is incorrect, citing the specific IEEE standards
>and the specific section numbers from those standards
>would be helpful.