Multicast Delay OTV

[stephendrkw]

Hi,

I have 2 Data Centres connected with DWDM about a 0.5ms delay. When a host in one DC initiates a Multciast Join I am seeing 1.2 second delay within IPN, I have 2 x 7700 Nexus in each DC with packet captures running on the OTV edge facing IPN, my packet captures proves this delay. There are 2 applications affected where the Server daemon is not working properly as it expects a quicker response (response it taking too long 1.7 seconds in total) and is a financial product, other applications are not so sensitive to this delay, I should say after the initial delayed join Multicast streams work perfectly with no problems.

1.2 second is large I know that you have to convert each from PIM-SM multicast stream to SSM within the IPN then to PIM-SM but this is extremely poor, there is also lack of detailed documentation on OTV Multicast. How can Multicast packets take 1.2 seconds within IPN? TAC has been raised and the above captures have been provided to Cisco.

Any experiences or Multicast OTV knowledge would be helpful.

fyi - I have traced detailed mrouter hops, DR, RP - the whole path process and OTV/IPN delay is the issue here.

thanks

[stephendrkw]

Cisco labs have come back finally and confirmed that there is indeed a delay of 1.2 - 1.5 seconds across OTV to initially start a multicast stream. We have removed this stream from OTV and have created a Layer 2 link across buildings to fix our problem. Cisco recommended to change the adjancey to unicast

interface Overlay2
otv adjacency-server unicast-only

this saves about 500ms they say, so I have setup a separate test Vlan for unicast and will test multicast.

I wouldn't recommend using OTV if you work with multicast a lot, like a financial.

[stephendrkw]

We changed OTV multicast to encapsulate UDP over unicast for traffic across OTV as recommended by Cisco, the multicast delays went from 1.5-2 seconds down to approx 20ms. What an improvement!