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Inline OTV with multiple DCIs - DCI failure question.

D R
Beginner
Beginner

Hello.

Assuming the topology in the attachment (inline OTV with unicast mode), an extended VLAN is currently flowing via DCI circuit 1.Assume the DCI circuits are not dark fibre but are an ISP provided layer 2 circuit so in theory there could be a circuit failure that causes traffic interruption but the join interfaces remain up/up.

What happens with OTV in this scenario? I'm assuming the overlay will eventually timeout. Will the secondary ASRs connected to DCI circuit 2 become the AEDs for the VLAN that was flowing over the failed circuit automatically? What happens when DCI circuit 1 recovers?

Is an OTV on a stick deployment generally recommended over OTV linline simply to reduce failover time? Where the DC core terminates the two DCIs and provides routing for the OTV join (e.g. EIGRP with BFD).

Kind regards.

2 Accepted Solutions

Accepted Solutions

HI D R,

My understanding is that as soon the Overlay goes down (in this case it will time out eventually) it looses its AED  capability. So eventually, I assume the the redundant edge device will become AED for all vlans. I am expecting the below output under OTV when your adjacency goes down.

sh otv

<SNIP>

AED-Capable         : No (No Overlay Remote Adjacency up)

Hope this helps,

Madhu.

View solution in original post

Also when your circuit recovers, again it will take over the AED role for the vlans it was handling before.

Is an OTV on a stick deployment generally recommended over OTV linline simply to reduce failover time?

From an OTV perspective there is no difference between the two models.

The main advantage of the Appliance on a Stick model is that no changes to the design or to the physical connections would be required once the dependency from the OTV VDC is removed. The only migration steps at that point would be to move the OTV configuration from the OTV VDC to the Routing VDC and deactivate the OTV VDC. This would be transparent to the rest of the data center network.

Reference : 

http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI3_OTV_Intro/DCI_1.html

http://www.cisco.com/c/dam/en/us/products/collateral/switches/nexus-7000-series-switches/guide_c07-728315.pdf

View solution in original post

6 Replies 6

HI D R,

My understanding is that as soon the Overlay goes down (in this case it will time out eventually) it looses its AED  capability. So eventually, I assume the the redundant edge device will become AED for all vlans. I am expecting the below output under OTV when your adjacency goes down.

sh otv

<SNIP>

AED-Capable         : No (No Overlay Remote Adjacency up)

Hope this helps,

Madhu.

Also when your circuit recovers, again it will take over the AED role for the vlans it was handling before.

Is an OTV on a stick deployment generally recommended over OTV linline simply to reduce failover time?

From an OTV perspective there is no difference between the two models.

The main advantage of the Appliance on a Stick model is that no changes to the design or to the physical connections would be required once the dependency from the OTV VDC is removed. The only migration steps at that point would be to move the OTV configuration from the OTV VDC to the Routing VDC and deactivate the OTV VDC. This would be transparent to the rest of the data center network.

Reference : 

http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI3_OTV_Intro/DCI_1.html

http://www.cisco.com/c/dam/en/us/products/collateral/switches/nexus-7000-series-switches/guide_c07-728315.pdf

Apart from the above, please keep in mind there is no AED - reelection if your internal interface goes down, unlike your join interface going down or OTV VDC going offline.

So ensure you have redundancy in place for the internal interfaces too via port-channel or VPC(if two DC cores are used).

Hope this helps and kindly remember to rate the posts if you find them useful.

Regards,

Madhu.