Jumbo or not to Jumbo?

15.11.19 - Reading time: 2 minutes

Occasionally I spend some time in discussions with customers and co-workers about the need to use Jumbo frames or not.

In my opinion, you don't need Jumbo frames in a 10G+ world.
And here is why:

Facts

  • Jumbo frames have lower overhead since fewer packets are transmitted for a given workload
  • You need to configure every device in the transport stream for Jumbos
  • There could be some performance plus
  • Many storage vendors have Jumbos as best practice

What I see in daily business

  • With modern NICs and and Switches you can transfer way enough packets to saturate a 10G+ link with standard packet size
    • If you need more performance --> consider an upgrade to higher bandwidth
  • Setting Jumbos on all Interfaces (sometimes: vm / vmkernel, vSwitch, Switch, Trunk, VLAN, Port, Storage) can be difficult for an Sysadmin
    • and it tolerates no issues or glitches... --> Consider automation if needed
  • The performance plus is marginal compared to complexity (around 5% plus in performance)
    • also consider an upgrade, if more performance is needed
  • Often Jumbos are best practice as no vendor wants have 5% lower performance while POCs
    • but in real life you will see no difference between 9000 and 1500 at all

Conclusion

If you have a Greenfield installation you can consider using Jumbos.
But in a Brownfield (which is about 90%+) stay on 1500.

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