On Wed, Mar 21, 2012 at 12:44 PM, Worley, Dale R (Dale)
<dworley(_at_)avaya(_dot_)com> wrote:
OK, I know nothing about the subject, but when I do "ifconfig" I get:
eth0 Link encap:Ethernet HWaddr 00:16:35:AF:82:03
inet addr:135.55.22.90 Bcast:135.55.22.255 Mask:255.255.255.0
inet6 addr: fe80::216:35ff:feaf:8203/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
[...]
Looking at the link-local address, it appears to be constructed from
the interface's MAC address, and basically nothing else.
This suggests that the link-local address of another system on an
attached network would contain that system's MAC address, but nothing
to identify which network, and thus, *this* system has no algorithmic
way to determine which interface goes to the proper network.
You've just rediscovered what the "link local" part of the link-local
address means: the address is local to the link! It is not globally
unique or even unique within a host, it is just unique within a link.
Thus, if a host has more than one interface (and most do: at least one
network interface + loopback, which is a separate interface), you need
to tell it which one you mean when you use link-local addresses.
--
Craig A. Finseth