[CLUE-Tech] Cisco 678 Configuration

[black at galaxy.silvren.com]

> But, I could not ping my LAN host from the 678's management interface.
>
> The LAN host I am referring to was a laptop hooked directly
> to the 678 via a cross-over cable.
>
> What are multicast MAC addresses?  And who/what/why use(s) them?

Multicast is used so that multiple recipients can receive a single
message, and it doesn't have to be sent to them individually one at a
time (unicast). It's a lot like a broadcast, except not every host on the
network is obliged to look at the frame, only the hosts wanting to receive
multicasts on that particular MAC address.

Multicasts at layer 2 start with "01:00:5E"

http://www.hep.ucl.ac.uk/~ytl/multi-cast/addresstranslation_01.html has
some info on this, I googled it real fast. I'm sure there are better
sources, but this has general info.

The most typical use of multicast on a LAN I see is routing protocols like
EIGRP, OSPF, etc. Some applications use them as well. Anything that is
sourced from a single location and is being sent to multiple recipients on
the same LAN segment (like streaming video from the CEO going to your
desktop for example) is a good candidate for it.

Why you'd be seeing those as belonging to your 678, I don't know.