[c-nsp] Mac address flapping..

[A.L.M.Buxey at lboro.ac.uk]

hi,


i originally thought on the same lines too - but then having 
been told this still happens if theres only one link
to the 4500s to the client - which makes the 6506-b almost
a router at the end of a stick for that network things started
to look a little 'wonky'.  it wouldnt be taking traffic from
another port(?).

as far as i now see, you have 2 routers, A and B.   A has the feed to
the switch (and the only physical link to the customer) whilst
B is connected to A via a portchannel and trunk link. a MAC for
vlan042 is still flipping between the down-link from A and the
link from A to B.  now, from my deepest memories I've seen this sort
of thing happen on our campus in the past... i've got some feeling that
somewhere, that VLAN is being fed into your network as another VLAN
and therefore the AMC is squirting back out and through - eg native vlan 042
is patched to vlan 1 or somesuch elsewhere, therefore the MAC is seen
coming back t;other way

alan