Jumbo Frame Support on Virtual Connect (VC)

[chuckk281]

Aditya had a Jumbo Frame question from a customer:

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Hello,

We have a customer deployment, where we would like to enable Jumbo Frame support on the TOR and the individual blades. The current enclosure is a c7000 with Oneview 1.20 as the management utility. The blades are are BL 460C G8.

I would like to understand if there is there is a specific configuration that we would have to do at the VC module level to achieve this?

Does Oneview support Jumbo Frames?

Has anyone tried enabling Jumbo Frames in their customer environments before?

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Input from Kevin:

The VC switch fabric has jumbo frames enabled by default. OneView is a management appliance and basically has nothing to do with the capability of jumbo frames.

From Hongjun:

Did anyone verify this in the lab? I always thought that’s the case but my test couldn’t prove it.

I didn’t see my ping test go above 1500 bytes MTU. I made sure all NICs are mapped to the same virtual connect module to rule out TOR MTU issue.

I tried one CentOS VM(vsphere DVS MTU already raised) and a windows OS blade to ping another windows blade in the same enclosure. All NICs involved are mapped to the 1^st VC module.

Both my linux VM and windows source blade couldn’t ping above 1500 MTU ( with ICMP payload max at 1472 bytes +8 bytes of ICMP header + 20 bytes IP header).

Reply from Kevin:

We get this case asked of us at least 3 times a week in the response center. We have proven to the customer several times it is on by default. Remember jumbo frames if set has to be set within the physical path of two peers to work properly so there is no fragmentation.

Reply from Hongjun:

Thanks Kevin!

I forgot to increase windows driver side MTU size, after doing that, large packets can go through. My bad.

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