Virtualisation - trunking Vlans

Unanswered Question
Sep 6th, 2009


I am working on a requirement on virtualisation involving Business crtical applications in multiple data centers. The challenges being currently faced are:

1. The 3 Tier architecture with web servers, app servers and db servers to be virtualised with common ESX hosts along with multiple other intranet applications. Issues around security between environments, management of ESX, logging etc.

2. multiple swtiched environments to be virtualized with clash of Vlan id's, Vlan in excess on 512 to be trunked.

3. The ultimate goal is to go for the complete virtualised environment with full DR capability and flexibility akin Cloud computing.

4. Can we think of Q in Q support on Nexus 1000v?

Any help in untangling this situation will be highly appreciated.


I have this problem too.
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bhedlund Mon, 09/07/2009 - 07:16


With 512 VLANs just keep in mind you are at the upper limit of Nexus 1000V number of active VLANs supported (512).

While the Nexus 1000V does not support Q-in-Q, the best place to implement such a feature would be at the physical switch layer anyway.

Or perhaps another approach would be to implement your own VPLS cloud to interconnect the various switched environments together. The VLAN #'s dont need to be the same at each location, you could for example have VLAN 10 at Site A bridged to VLAN 20 at Site B. The advantage of VPLS over plain Q-in-Q would be preserving STP isolation and autonomy between sites.

Also, talk to your Cisco SE about OTV for Nexus 7000 :)



p.s. please rate if helpful

john_t_mathai Mon, 09/07/2009 - 22:33


Thanks for the reply. The issue is at single location itself wherein the number of vlans and clash of vlan id's. Any workaround for that you can think off. Can't think of renumbering of the vlans.

Also on a different note, Is there a architecture available on tiering in the cloud computing for internal or public?


bhedlund Wed, 09/09/2009 - 17:11


Please clarify... How do you have "clash of vlan id's" at a single location? Do you have multiple physically separate networks at this single physical location, each with the same vlan #'s, that you are now trying to interconnect at L2?



john_t_mathai Wed, 09/09/2009 - 16:36


You got me right, there are currently seperated Layer 2 Vlans and trying to use the VSF across these disparate networks. These are on different IP subnets and connect on laer 3 otherwise. Trying to see if these VSF can be used across and meanwhile design for the complete new DC for future.


george.karavitis Tue, 04/27/2010 - 02:29

On a similar project we are running, we are moving towards OTV, so I will agree with Brad that maybe you want to look into it.

Downside it is a very new technology for Nexus 7k and there is currently only pre-release of the feature. We had to get into cisco labs to see it actually working.




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