[c-nsp] nexus-switche issues no arp-requests

[Oswald, Thomas]

Hallo all,

I see a very strange behavior on my two nexus switches.

Both are Nexus 5548 with L3-daughter-cards. Both do l2 and l3-switching, ACL-filtering and other things. Furthermore I have a set of servers connected to both switches in a vPC-setup. All in all I do nothing special.

After reloading the primary switch (vpc-primary, root-bridge for all vlans and hsrp-active with preemption for all SVIs) the switche comes back online and after getting up all links and reconverging everthing the network breaks. After a lot of debugging and curses and connection tries and a few additional gray hairs later I have got it to work by pinging all ip-addresses from the switch that I have previously rebooted.

Later I do some tests to find out what was going wrong. I found out that if I clear the arp-cache I will get the same issue. Pinging from server A in one subnet to server B in another subnet doesn't lead to success, because the switch issues no arp-requests. To make it work just ping server B from the switch and all works fine. The switch does arp, the arp-table is updated and the pings from the server A will reach the server B.

Any ideas?

Regards
Thomas
^^°-°^^