pf and different MTUs

Chuck Swiger cswiger at
Fri Jan 28 13:36:14 PST 2005

Michael E.Conlen wrote:
> I'm using FreeBSD and PF as a firewall between two  networks. I want to 
> change the MTU on one network to 9k but I have to leave the MTU on the 
> other network at 1500 bytes. Will the system handle the fragmenting for 
> me going from the larger MTU to the smaller?

Sure.  However, if you have a lot of traffic using jumbo frames going over 
that 1500 MTU segment, you might be better off using an MTU of 1500 everywhere.


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