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New Member

Jumbo Frames

Could somebody please confirm my assumptions on the operation of Jumbo Frames.

1.) If two servers on the same VLAN are configured for jumbo frames they will communicate at the higher frame size.

2.) If a client on the same VLAN does not support jumbo frames the highest MTU size available for communicating to a jumbo frame enabled server will be 1518 bytes.

3.) same question as question two except the client is on a different VLAN.


New Member

Re: Jumbo Frames

Make sure all interfaces in a VLAN are configured for jumbo frames before configuring jumbo frame support on an SVI. A packet’s MTU is not checked on the ingress side of an SVI. However, it is checked on the egress side of an SVI. If the packet’s MTU is larger than the egress SVI’s MTU, the packet is fragmented by software (if the DF bit is not set), which results in poor performance. Software fragmentation only happens for L3 switching. When a packet is forwarded to an L3 port or an SVI with a smaller MTU, software fragmentation will occur.

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