MTU

By | 03/08/2015

MTU – Maximum transmission unit

PMTUD – Path MTU Discovery

Links have a maximum packet size limitation depending on the protocol/technology. MTU defines the maximum bytes of a packet on a link.

With PMTUD, endpoints are capable of determine the MTU of a path.

When a endpoint sends a packet larger than the MTU, this is fragmented on the network devices that have a lower MTU. The packets will be reassembled at the destination.

PMTUD is not supported for UDP.

Fragmentation makes network less efficient, same as a lower MTU.

 

Reference:

http://www.cisco.com/c/en/us/support/docs/ip/generic-routing-encapsulation-gre/25885-pmtud-ipfrag.html