Mark Butler wrote:
jamal wrote:
On Fri, 2006-07-04 at 17:20 +1000, Anand Kumria wrote:
On Fri, 31 Mar 2006 15:26:00 -0800, David Daney wrote:
From: David Daney
Greetings,
When an internet host joins a network where there is no DHCP server,
it may auto-allocate an IP address by the method described in RFC
3927. There are several user space daemons available that implement
most of the protocol (zcip, busybox, ...). The kernel's APR driver
should function in the normal manner except that it is required to
broadcast all ARP packets that it originates in the link local address
space (169.254.0.0/16). RFC 3927 section 2.5 explains the
requirement.
The current ARP code is non-compliant because it does not broadcast
some ARP packets as required by RFC 3927.
I haven't seem anyone comment on this,
Theres a lot of comments - check the archives of netdev on the thread
as well as a newer thread under "Broadcast ARP packets on link local
addresses (Version2)"
but it would be useful to see this
integrated.
IMO not the way it is defined right now in that patch. As suggested
in the thread, best way is for the kernel to check
if it is link local and do the advert in broadcast instead of unicast.
Something else I've noticed while I've been implementing my zeroconf
daemon is that the kernel returns link-scoped primary addresses
first to
'ifconfig'. Unfortunately quite a lot of user-space programs parse its
output and interpret the address it presents as the primary for the
specified interface.
Not sure i followed.
Is that a case of user-space breakage that the kernel team would
ordinarily worry about?
I think user space setting the attribute of the address to be link local
would be a sufficient hint to the kernel to broadcast the arps.
In IPv4, how is this information supposed to be communicated? The
possibilities I can see are:
1. Assuming link local based on SO_BINDTODEVICE.
2. Adding a new field to sockaddr_in in a backward compatible manner
3. Defining a new RTAX_xxxx route attribute
Excuse me, I didn't realize the routing tables already had an
(apparently customizable) attribute for address scope. OF course, why
anyone would need to use a non-standard IP address range for link local
addresses is a separate issue. Isn't a /16 enough?
- Mark B.
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