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srl-labs / containerlab

container-based networking labs
https://containerlab.dev
BSD 3-Clause "New" or "Revised" License
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Make default MTU settings more realistic #392

Closed networkop closed 3 years ago

networkop commented 3 years ago

The current MTU default is 65000 which is not realistic in physical networking context. Could we change this to e.g. 9000?

jbemmel commented 3 years ago

Or 9001 like aws

hellt commented 3 years ago

as we synced with @networkop offline and briefly discussed this I am inclined to close it with the following reasoning:

containerlab doesn't need to impose any limitation by default on the underlying network carried out via veth pairs. We took 65k as this is ~max MTU for the veth link in linux kernel.

The idea here is that the NOS that starts will impose its max MTU on the links that it senses are available. To not be in the way of the NOS defaults we jack up the MTU. So far this was never a problem and it is not also an issue with the platform @networkop is working with.

So how about we park it for now since no-one has issues with 65k MTU so far except for it being non-natural and see if this causes any issues in the long run.