MTU mismatch between stack and Datacenter

[andyny]

Dear experts, 

Azure stack comes with pair of TOR switches that should establish bgp to the external DC switches. AFAIK , Stack TORS is configured with an MTU of 9216. 

Do you anticipate any problems in egress/ingress connectivity to the stack if Datacenter switches has different MTU settings ? 

My expectation that only end-to-end connectivity MTU ( e.g. VM on stack to VM in the DC ) matters. Do you know if all VM and services in stack hub will have 1500 ? 

Thank you !

[#2]

Usually, the MTU sizes differ with each OEM device, but the 92xx size is in the correct range. It is best practice to match the border switches MTU size to that of TORs.

As for the VMs, yes – same as Azure, our MTU sizes are set at 1500.

Your OEM should help you figure these out though and make the respective changes accordingly.

[#3]

@rctibi Thank you for reply.

OEM does not allow us to change MTU settings on the Stack switches, and our DC using other value of MTU.

It seems that MTU mismatch will not cause problem for us, since source and destination would have MTU of 1500.

[#4 · Accepted solution]

@andyny if you get any issues, open a support case (either with the OEM, or with Microsoft) and we can have a look at what's going on. Getting these right is important and as a production workload, you will be better off using support to have a look at these (rather than this forum I mean) :)

good luck! and all the best!