Subject: RE: Fwd: linklocal + DHCP servers

From: "Bernard Aboba" <[email-masked]>
Date: Tue, 23 May 2000 07:40:40 -0700

>Given the derth of publication on the IPv4 link-local address,
>I'd be surprised if -any- code base treats the 169.254.0.0/16 
>prefix as unique. And given its recent vintage and a lack of
>understanding of the longer term impact, I'd be shocked if 
>this had even made it to SOP status.   It will be a -very- long
>time before this has the same status as the loopback space.

So are you saying that we should just treat 169.254/16 as 
another private prefix and forget about it being linklocal?
Or that additional precautions need to be taken, like
sourcing packets from TTL=1?

---

From: Daniel Senie <[email-masked]>
Date: Tue, 23 May 2000 10:41:59 -0400

> sourcing packets from TTL=1?

It's worse than that... you'd also have to reject any DHCP relay
packets. The TTL on DHCP relay packets is not necessarily predictable.
All relay packets would be an indicator that the DHCP server has no
direct attachment to the LAN segment in question.

There's also the issue of the DHCP server having to use the link info
along with the IP address for keeping its records. After all, the same
DHCP server might be serving multiple directly-attached LANs. So for
example, 169.254.45.109 might exist on three different LANs, but refer
to three different stations. If those were self-assigned, not assigned
by the DHCP server, the server must nonetheless track them.

This whole area quickly becomes a significant can of worms, adding
complexity to an existing, deployed protocol, with questionable and
limited advantages.

-- 
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Daniel Senie                                        [email-masked]
Amaranth Networks Inc.                    http://www.amaranth.com