[c-nsp] Nexus 7k and OTV

[Matthew Melbourne]

>From talking to our Cisco SE, the initial release of OTV will likely
on support a low-ish number of VLANs, with the likelihood that the
number will increase over time as additional testing is performed. A
back-to-back vPC between pairs of Nexus make work between two DCs, but
separate physical links for L3 interconnects may be an issue. Given
this may scale to more than two DCs, solutions such as VPLS/A-VPLS
begin to look attractive.

BTW, is is permissible to use a vPC peer link between two Nexus for
non-vPC traffic; thinking in the scenario where the access layer
design comprises of squares rather than triangles.

Cheers,

Matt

On 22 July 2010 13:13, Lincoln Dale <ltd at cisco.com> wrote:
> On 22/07/2010, at 8:16 PM, Matthew Melbourne wrote:
>
>> Is it possible to extend two vDCs between Data Centres using OTV (pair
>> of N7k on each site) - it's not clear how OTV uses vDCs to extend the
>> L2 domain.
>
> yes, its possible.  there are 3 methods:
>
> 1. OTV runs inside a Virtual Device Context.  for 2 VDCs you could run OTV in each of them.
>   this approach requires 'WAN' connectivity to each VDC - perhaps a downside if its not already there.
>
> 2. if you don't have overlapping VLANs between the VDCs then you can trunk the VLANs (L2) from one VDC to another using a crossover external cable (1G or 10G or Nx1G/10G depending on your traffic levels), then use a single OTV instance to transport all the VLANs between sites.
>
> 3. you could run a single instance of OTV within each VDC (similar to #1) with the 'WAN' IP connectivity to the OTV cloud achieved via a single VDC with a crossover external cable (1G or 10G, doesn't really matter) @ L3 between VDCs to the single VDC that has WAN connectivity (similar to #2).  i.e. sort of a hybrid of the above two.
>
>> Also, is it correct that Unicast-only transport support (and hence the
>> use of an Adjacency Server) is not supported initially (looking at the
>> BRKDCT-2049 Networkers' presentation).
>
> correct.
>
>
>>
>> Alternatively, are there other mechanisms to achieve L2 connectivity
>> for two separte L2 domains over a pair of redundant links between Data
>> Centres?
>
> quite a few ways of doing it, but OTV does solve some unique problems and issues with the various other approaches.
>
>
> cheers,
>
> lincoln.



-- 
Matthew Melbourne