* wabe <waben...@gmail.com> [160919 20:50]: > Grant <emailgr...@gmail.com> wrote: > > > A while back I was having networking issues. I eventually tried > > drastically lowering the MTU of all the systems onsite and the issues > > disappeared. I always thought the issue was due to the MTU on our > > modem/router. Today I read that AT&T DSL requires a 1492 MTU so I > > increased the MTU of our systems up to 1492 and haven't had any > > issues. Do certain ISPs require you to change the MTU of your entire > > network, or is this likely due to our AT&T modem/router itself? > > AFAIK the MTU is defined for every network interface separately. For an > ADSL connection it is common that a lower MTU is needed because of the > PPPoE header information that is encapsulated in the ethernet frames. > But in that case it is sufficient to lower the MTU just for the WAN > interface that is connected to the DSL modem. > If you don't use protocol encapsulation in your LAN then there should > be IMHO no reason for lowering the MTU of your internal interfaces. > > -- > Regards > wabe
MTU is per network interface but you really don't want to end up having your router fragment every IP packet because systems on your subnet are using a larger MTU. Todd
