Nexus VLAN AED selection

[josephschung]

Sir,

We have two data centers with a pair of Nexus 7000 in each of them. We use OTV to extend the existing VLANs below to serve across site traffic.

10

16

17

40

41

42

We found that 10, 16, 40 and 42 are going through the first Nexus while 17 and 41 are going through the second one, which is exactly what the Cisco document described that "VLANs are split as odd and even VLAN IDs on each edge device". But, the load is not well balanced!

So my questions...is there any way we can redistribute the vlans so that they are evenly allocated between the two Nexus? How can we assign a particular VLAN to a specific Nexus?

Thank you.

[Kevin Dorrell]

Hi,

I found your posting while I was looking for something related to the even/odd split.  As far as I know, at this date the behaviour is fixed, and depends on the system id of the switches.  The lower system id gets the even numbered VLANs and the higher system id gets the odd numbered VLANs.

However, I did hear at Cisco Live! this year that it is planned for a future release to be able to allocate specific VLANs to specific AEDs in the same sort of way that you allocate VLANs to MST instances.  That will be great, because if you are using MST, it will make it easier to keep the spanning-tree root in correspondence with the AED.

I think it will still be on a per-VLAN basis, that is, you will not be able to load-share a single VLAN between AEDs.  So if you have a VLAN that carries much more traffic than the rest put together, you will still have the imbalance.

Kevin Dorrell

Luxembourg

[jkilleda]

Hello Si,

Nexus VLAN AED selection
OTV is designed to work in that way ; VLAN's are differented as odd and even VLAN's so that AED with higher MAC address will become active for odd VLAN's and AED with lower MAC address will become active for even VLAN's