Interface MTU / Protocol MTU

10.11.17   |  
‎10-11-2017 11:46 PM

Hello, trying to learn MTU concepts, they keep cropping up in interviews. Why do we have Interface AND Protocol MTU configuration values? Why not just one?  I though that once you set the interface MTU up that was it but within Junos (and maybe other platforms there is also the concept of protocol MTU


Thanks in advance




Re: Interface MTU / Protocol MTU

10.12.17   |  
‎10-12-2017 05:47 AM

The media (interface) mtu is what can be supported by the physical link.

The protocol mtu is what is supported by the transport protocol running on the interface (typically ip these days)


Here is the juniper documentation on them.


media mtu

protocol mtu

Steve Puluka BSEET - Juniper Ambassador
Senior IP Engineer - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)