Subject: draft-ietf-zeroconf-ipv4-linklocal-05.txt with IPv6/IPv4 stack

From: Markku Savela <[email-masked]>
Date: Fri, 19 Jul 2002 17:39:17 +0300

It has been dumped on me to implement IPv4 link locals into IPv6/IPv4
stack.

In this stack Most of the code is shared between IPv6 and IPv4. Thus,
I would have hoped to have as little extra warts as possible in the
control paths.

In general, the IPv4 link local fits quite well, when you handle them
the same as IPv6 link local.

The control logic of IPv6 duplicate address detection (DAD) works
almost as is with this (by just tweaking the parameters: number of
DAD's, etc.). IPv6 does not include the "announcement part" (not a big
problem).

However, requiring TTL to be 255 whenever source or destination is
link local is a bit jarring. It would be nice if both IPv6 and IPv4
had same logic in this.

I wonder what would break if I just require the same with IPv6 link
locals (most of the link local use there is ND, which already requires
hoplimit=255)?

---

From: Stuart Cheshire <[email-masked]>
Date: Tue, 30 Jul 2002 21:14:32 -0700

>locals (most of the link local use there is ND, which already requires

I think the same logic that makes TTL 255 a good idea for other 
link-local applications, also applies equally well for IPv6 link local 
packets.

You could argue that a customer is less likely to have a misconfigured 
IPv6 router that inadvertently forwards inbound packets containing 
link-local addresses, but that's not a strong argument that the hoplimit 
should NOT be set to 255.

Stuart Cheshire <[email-masked]>
 * Wizard Without Portfolio, Apple Computer
 * Chairman, IETF ZEROCONF
 * www.stuartcheshire.org