[c-nsp] Nexus OTV Question

Martin Clifton Martin.Clifton at vu.edu.au
Sun Feb 27 18:16:31 EST 2011


Hello all,

We have a pair of Nexus 7Ks at each of our two datacentres, separated by about 10K.   There is a 40G L3 connection between the cores at each site and we run OTV over this core to provide L2 connectivity betweens the DCs.  As well as setting up new vlans on the Nexus kit (5Ks and 2Ks) we are also using the OTV connection to transport vlans from our legacy datacentre which is based on Cat6509s and 3750s.

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.

This doesn't appear to impact the functionality of OTV.   But does it indicate I have a problem ?   What is it that causes the reset and why are all the (overlay) mac addresses reset at the same time ?    The symptoms occur whether or not "otv suppress-arp-nd" is enabled or not.

Regards, Martin

---------------------------------
Martin Clifton
ITS - Networks and Computing
Victoria University
Melbourne, Australia

Phone: 03 9919 4579
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