Subject: [dhcwg] Fwd: DHCP MTU option 26?

From: Ralph Droms <[email-masked]>
Date: Wed, 17 Feb 2010 08:14:11 -0500

Anyone have an answer to this question?  Likely most interesting to  
know if it is implemented on RGs; info on host clients (Windows, OS X,  
Linux, etc) would be of interest, as well.

- Ralph

Begin forwarded message:
>
> Anyone know if this is implemented regularly at all in practice? And  
> if at all, on broadband uplinks?
>

---

From: Ralph Droms <[email-masked]>
Date: Wed, 17 Feb 2010 07:56:37 -0500

- Ralph

---

From: "Van Aken Dirk" <[email-masked]>
Date: Wed, 17 Feb 2010 14:25:38 +0100

Hello Ralph,

As a vendor or BB Gateways (Alcatel SpeedTouch xDSL Gateways, Thomson
xDSL Gateways) I'm not aware of an implementation.
I'm thinking of implementing this in the future as we a gradually
confronted with larger MTUs in the public access network.

Br - Dirk Van Aken

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf
Of Ralph Droms
Sent: woensdag 17 februari 2010 14:14
To: dhc WG
Subject: [dhcwg] Fwd: DHCP MTU option 26?

- Ralph

> if at all, on broadband uplinks?

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---

From: "David W. Hankins" <[email-masked]>
Date: Tue, 23 Feb 2010 13:14:51 -0800

On Wed, Feb 17, 2010 at 08:14:11AM -0500, Ralph Droms wrote:
> Anyone have an answer to this question?  Likely most interesting to know if 
> it is implemented on RGs; info on host clients (Windows, OS X, Linux, etc) 
> would be of interest, as well.
>
> Begin forwarded message:
>> Anyone know if this is implemented regularly at all in practice? And if at 
>> all, on broadband uplinks?

Awhile ago (2007?) there was some interest in "DHCP Fingerprinting."
This is actually the technique I used in configuring the DHCP server
on the "4-6-4" NAT network during the IETF experiment to disable the
access to the IPv4 internet during the plenary, so that we could
produce a demographic of "hosts fleeing the IPv6-only network."

The version of the DHCP Fingerprinting database I pulled from (and
can't remember anymore) lists 3 fingerprints that include option 0x1a,
26, and they're all listed as "Linux."

A cursory google for another fingerprinting database turns up a small
smattering of other clients; Windows NT 4 (but not later, more modern
versions of Windows), the Nintendo GameCube, a smattering of printers
and Linksys and Gemtek routers.

    http://www.packetfence.org/dhcp_fingerprints.conf

I think in general more broad support of the MTU option would be good
in resolving the many issues of MTU size mismatches on modern media.
We may want to consider a DHCPv6 option for MTU size configuration.

-- 
David W. Hankins	BIND 10 needs more DHCP voices.
Software Engineer		There just aren't enough in our heads.
Internet Systems Consortium, Inc.		http://bind10.isc.org/