Hi, We are seeing very odd L2 connectivity on some vPCs between a pair of Nexus 7018 (NX-OS 5.0(2a)) and a ToR switches. For example on an ASR connecting to Nexus, trying to connect to a host plugged into a downstream switch (with a vPC to the Nexus pair), connectivity will be lost, but a refresh of ARP traffic, e.g. 'clear ip arp <IP address>' restores connectivity momentarily, even though the MAC address on the ASR hasn't changed.
On the affected vPCs, we noticed that the native VLAN appears to be set to 4095 (which isn't a valid VLAN on the switch) on one of the Nexus in the pair (nx02), e.g. nx02# show interface switchport | i 4095 prev 5 Name: port-channel80 Switchport: Enabled Switchport Monitor: Not enabled Operational Mode: trunk Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 4095 (Vlan not created) -- Name: port-channel101 Switchport: Enabled Switchport Monitor: Not enabled Operational Mode: trunk Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 4095 (Vlan not created) -- Name: port-channel102 Switchport: Enabled Switchport Monitor: Not enabled Operational Mode: trunk Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 4095 (Vlan not created) Additionally, if the ‘show interface switchport’ command is issued against any of these vPCs the following message is generated: 2011 Feb 21 10:12:01 nx02 %VLAN_MGR-2-INFO_MSG: pid 11274, vdcID 0, local vdcID 1 When looking at ‘show interface switchport’ on the member interfaces of the relevant port-channel the native VLAN is VLAN 1 as expected. If any L2 switchport commands are entered under these port-channel interface on the problematic Nexus (nx02), the command is rejected: nx02(config-if)# switchport trunk native vlan 1 Warning: command rejected, Po102 not a switching port It is possible to apply the command to the member interface, but the member interface was correctly displaying a native VLAN of 1 anyway – the problem only affects the port-channel interface. After applying the command to the member interface the port-channel interface still shows a native Vlan of 4095. This is only affecting one Nexus (nx02). The native VLAN on the affected port-channels on nx01 is correct. Shutting down the member port on nx02 fixes the strange connectivity issue for the affected port-channels - and given that this native VLAN issue is affecting the same vPCs, we're fairly sure these issues are related. Has anyone seen anything similar; the code on the units is 5.0(2a), and the issue only appears to be affects some vPCs on one of the Nexus? Cheers, Matt -- Matthew Melbourne _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/