RE: [dhcwg] RFC 3256 on The DOCSIS Device Class DHCP

"Woundy, Richard" <> Fri, 19 April 2002 19:25 UTC

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From: "Woundy, Richard" <>
To: 'Bud Millwood' <>,
Subject: RE: [dhcwg] RFC 3256 on The DOCSIS Device Class DHCP
Date: Fri, 19 Apr 2002 13:22:45 -0600
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According to the DOCSIS specifications, a DOCSIS 1.0 CM may include the
value "docsis1.0" in DHCP option 60, and a DOCSIS 1.1 CM must include the
value "docsis1.1" (followed by additional data in the string).

See: <>
appendix C.1.1, and
<> appendix D.1.1.

Note that some relay agents (e.g. broadband aggregation routers acting as
ATM VC aggregators for DSLAMs) may not have as much information about the
subscriber premise equipment as DOCSIS CMTSs...

-- Rich

-----Original Message-----
From: Bud Millwood []
Sent: Friday, April 19, 2002 4:50 AM
Subject: Re: [dhcwg] RFC 3256 on The DOCSIS Device Class DHCP

We have at least one customer making policy decisions on the server based on

the Class Identifier (option 60) value. Apparently, it's always "docsis1.0" 
for a DOCSIS cable-modem. (Not sure about docsis 1.1).

But even though this method appears to work fine in practice, I welcome this

new draft because of the security aspect, as well as the possibility for 
future expansion using the reserved bits.

I think it's important to let a trusted device give us as much information
possible about the clients we're servicing. So important, in fact, that I 
have wondered about the possibility of *requiring* *any* kind of relay agent

(DOCSIS or not) to insert option 82, with information about the originating 
machine (hwtype-mac, for example). The premise being that even in 
corporations, most routers are trusted equipment, usually locked away in a 
basement somewhere.

Bud Millwood
Weird Solutions, Inc.
tel: +46 70 566 7803
fax: +46 8 758 3687

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