Subject: LL10 applicability

From: "Philip Nye" <[email-masked]>
Date: Wed, 12 Feb 2003 11:26:17 -0000

Oohps - bad punctuation in my suggested text. It should read:

---
IPv4 link-local addresses and their dynamic configuration have
profound implications upon applications which use them. This is
discussed in Section 7. Many applications fundamentally assume
addresses of communicating peers are routable, relatively
unchanging and unique. These assumptions no longer hold with IPv4
link-local addresses, therefore while many applications will work
properly with LL addresses, others may do so only after
modification, or will exhibit reduced or partial functionality, or
will fail altogether.

The design requirements for IPv4 link-local address assignment
means that they are necessarily a compromise and they should only
be used where stable, routable addresses are not available (such
as on ad hoc or isolated networks) or in controlled situations
where these limitations and their impact on applications are
understood and accepted.
---

Philip

---

From: Keith Moore <[email-masked]>
Date: Wed, 12 Feb 2003 11:51:45 -0500

> discussed in Section 7. Many applications fundamentally assume

that

> link-local addresses, 

or a mixture of link-local and routable addresses.

> [T]herefore while many applications will work
> properly with LL addresses

, or a mixture of LL and routable addresses

> , others may do so only after
> modification, or will exhibit reduced or partial functionality

In some cases it may be infeasible for the application to be modified
to operate under such conditions.

> The design requirements for IPv4 link-local address assignment

(instead of the previous line)
were necessarily a compromise to favor usability in the absence of
address assignment infrastructure over stability of addressing and
ability to communicate with off-link hosts.  Such a compromise
makes sense for ad hoc or isolated networks, but not for links
that are connected to external networks.

IPv4 link-local addresses should therefore only 
> where these limitations and their impact on applications are

(it might be better to restate this as "use of v4LL should be avoided
when stable, routable addresses are available, except in controlled
situations where the set of applications is fixed and the impact of
v4LL on those applications is well-understood and accepted")