Re: [dhcwg] I-D Action: draft-ietf-dhc-dhcpv6-client-link-layer-addr-opt-00.txt

[Simon Hobson <[e-mail]>]

A. Gregory Rabil wrote:

>Another aspect of the option not being inserted by the client is 
>that it forces implementations (relays and servers) to read layer 2 
>information from the incoming packets. If the client provides this 
>information as an option, it works for all implementations without 
>such a requirement.

This has also been discussed before.
In an ideal world, we could just change the required client behaviour 
and all the vendors would update their clients and their users would 
update their software/firmware. Meanwhile, back in the real world, 
the opportunity to change clients has (largely) past - but there are 
fewer vendors of servers and relay agents which makes it a better bet 
to do this in the server or relay agent.

If ISC, Dibbler?, Cisco, and a handful of others update their 
server/relay agents, then that's probably the majority of situations 
covered where this is an issue. Plus, you can run a relay agent on 
something other than your routers - so even if your router vendor 
doesn't update, you can just fire up some small Linux/BSD/whatever 
box (can be a virtual machine) on the remote network and you're 
sorted.


In a way it's a parallel argument to using LL (MAC) addresses anyway. 
Again, in an ideal world the specs would have been updated to mandate 
a globally unique client ID, printed on the outside of the box 
(probably with a barcode as well), and sent by both the IPv4 and IPv6 
DHCP clients. Short of inventing a time machine and going back a 
decade or two, that's not going to happen.
So back in the real world again, at least in the IPv4 world we are 
stuck using LL addresses since they are the nearest thing we have to 
a universally present, globally unique, and immutable identifier.
-- 
Simon Hobson

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