lower MTU switch between higher MTU routers

[skrao_mandalapu]

Hi,

I have layer 2 switch with 1500 interface MTU between routers having having 9000 MTU. Does this layer 2 switch fragment >1500 packets?

Router A (9192 MTU) --------------(1500 MTU) Layer 2 switch (1500 MTU) -------------(9192 MTU) Router B

Also another connectivity is like below:

Router A (9192 MTU) --------------(9192 MTU)  Layer 2 switch  (1500 MTU) --------------(1500 MTU) Router B            how the fragmentation between Routers A and B?

Regards

Siva Kondala Rao

[rsimoni]

Hi Siva,

first scenario is wrong, the intermediate switch will drop traffic above 1500MTU.

Second scenario is fine and fragmentation will occur on L2 switch for frames above 1500 received from Router A going to Router B.

Riccardo

[skrao_mandalapu]

Thanks Riccardo, what about fragmentation in below scenario.

Router A (9192 MTU) --------------(1500 MTU)  Layer 2 switch  (9192 MTU) --------------(9192 MTU) Router B

Regards

Siva Kondala Rao

[santiago.martinez]

Siva, both interface on the same link needs to use the same MTU parameters.

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