[c-nsp] Nexus OTV Question

[Lincoln Dale]

hi Martin,

On 28/02/2011, at 10:16 AM, Martin Clifton wrote:
> I have a concern about the table that is displayed when you enter the command "sh otv route".   This table shows entries for "site" (ie local) and "overlay" (ie other DC)  mac addresses.    The issue is with the "Uptime" data.  For the overlay addresses this will randomly reset to zero and all addresses will reset to zero at the one time.   The frequency of this reset seems to be a function of the number of vlans ie the more vlans I add to the overlay, the more often the value resets.   With 100 or more vlans the value may build up to a minute or two but will often only get to a few seconds before resetting.

i would not expect the "uptime" in "show otv route" to be resetting.  that, to me, indicates that the MAC address(es) are moving/oscillating between ports on the originating device.
with OTV we still do hardware-based MAC learning for L2 switching but whenever a MAC address is learnt or moves that is picked up by control-plane and advertised accordingly.

for one of those mac addresses, suggest you look into whether it is in fact moving - and more importantly - why.  it could be a misconfiguration (like Port Channel "mode on" on one device and no Port Channel defined on the other end.
it could be misconfigured hosts - set up with NIC teaming or Link Aggregation incorrectly.
it could be unstable L2 at one side. 
t could be a loop.  (but i'd expect that to be having more noticable impacts on the network :) ).

pick one of the N7Ks where you see the change originating from and do a few "show hardware mac address-table <slot-number> | grep <macaddr>" and see if its moving.  that shows the h/w mac table.  you may also see the same moving of mac addresses in "show mac address-table" but the h/w one will show updates sooner.


cheers,

lincoln.