OTV changing the site VLAN

[DougBradley43966]

We have a multi-homed unicast OTV implementation using ASR-1001-X with two sites. One site was configured to use VLAN 1 as its site vlan.

VLAN1 is not allowed on the LAN, so the two ASRs cannot communicate.

I'd like to change the site-vlan for this one site to a VLAN which is trunked between the two ASRs.

Can someone please tell me what impact to expect with this change? Thanks!

[Sergiu.Daniluk · Accepted solution]

Hi @DougBradley43966 

If you change the site-vlan to one which is trunked between the two sites, the two OTV Edge devices will go into partial-adjacency because they believe they are in the same site, but with different site-id is configured on each of them.

Why do you need to change the site-vlan? In the end, if you have only one Edge device per site, there is nothing (except some KA messages) sent on that vlan.

Cheers,

Sergiu

[DougBradley43966]

Thanks for the reply; I'm sorry I was not clear.

This is a multi-homed implementation with two ASRs in each site. There are only two sites so unicast OTV was chosen. There is a total of four ASRs: two in each site.

The two ASRs in one site both have VLAN1 configured as their OTV site VLAN. Since VLAN1 not allowed on the LAN at the site, the two ASRs do not see each other and there is no site adjacency. 

OTV is working for the most part but am seeing what looks like odd lack of ARP, hence trying to iron out what look like anomalies (at least from reading the doc).

Has anyone changed the site vlan on a running OTV, and what was the impact?

[balaji.bandi]

If you are  changing  the Site VLAN, ISIS Process go down, you have downtime between the device and all the traffic will have distruption. so change the configuration in the maintenance window where the business can access small downtime like reconvergence take place.

[Sergiu.Daniluk]

Hello,

Sorry, I misunderstood that you want to allow vlan between sites.

Anyway, changing site vlan will have an impact on OTV process. Actually, doing changes like site vlan, site ID, it is recommended shutting down the overlay interface first.

Hope it helps,

Sergiu

[DougBradley43966]

Thanks very much!!

This community board is great, I hope I can contribute as well in the future.