Nexus 5596 | L3-Routing | Jumbo-Frame Support on sub-interfaces

[Ryukshen Rashidov]

  Facing an issue while routing Jumbo-Frames over a Nexus 5596 between multiple L3-instances due to the fact that the MTU has been set to 1500. The setup is containing 2 N5k's which are hosting the routing instances and L3-subinterfaces as well as SVI's which are running HSRP on top to provide L3 redundancy.

 The L2-policy has been set to forward Jumbo-Frames, but according to the Cisco documentation we need to set the MTU to 9216 on the L3-interfaces manually in addition.

  As we need to adjust the MTU on the L3-interfaces to route Jumbo-Frames, I would like to determine the impact of the adjustment activity and even like to know if it can be done in live environment. I will appreciate if someone can let me know if the MTU-size adjustment is seamless and non-disruptive on L3-instances as there is HSRP and as the two N5k have a VPC-peer?

[dukenuk96]

Did it on N9000, N5500, N5600 - no disruption, everything worked fine.

[Ryukshen Rashidov]

It appeared to be no issue here too.

[stlcisco]

HI

I'm looking to enable Jumbo frame for Nexus 5596 pair in teh data center. Was curious as to if it's service impacting and if i need to watch out for something. Any help is appreciated.. I'm planning on implementing soemthing like this. I have 4 FEX and lottts of VPC's for server connectivity with dual uplinks to N5K or the FEX.

Here's what i plan to implement:

policy-map type network-qos fcoe-jumbo
  class type network-qos class-fcoe
   pause no-drop
   mtu 2158

  class type network-qos class-default
   mtu 9216
   multicast-optimize
 
system qos
  service-policy type network-qos fcoe-jumbo