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nirvana21
December 10th, 2010, 04:06 AM
What layer does ifconfig operate at when setting a MTU. Does it set the MTU for the physical device (Network Interface Layer) or the MTU of the packet (Internet Layer)?

By executing

ifconfig eth0 mtu 1300
it leads me to believe this is causing the Network Interface Layer to be restricted because an interface must be specified. I am not sure of this though.

Can anyone confirm this for me? Furthermore, if anyone has a good source that would be great!

bab1
December 10th, 2010, 07:38 AM
What layer does ifconfig operate at when setting a MTU. Does it set the MTU for the physical device (Network Interface Layer) or the MTU of the packet (Internet Layer)?

Layer 2 (Ethernet) where ifconfig sets the MTU size. The MTU you are referring to is the frame size and for Ethernet (see here (http://www.networkingreviews.com/2008/02/29/the-base-of-ip-networks-osi-model/)) it is normally 1500. See here (http://compnetworking.about.com/od/networkprotocols/g/mtu-maximum.htm)for a basic discussion.


By executing

ifconfig eth0 mtu 1300
it leads me to believe this is causing the Network Interface Layer to be restricted because an interface must be specified. I am not sure of this though.

That is correct.


Can anyone confirm this for me? Furthermore, if anyone has a good source that would be great!

Here is a pretty good Google search (http://www.google.com/search?q=tcp+layers&btnG=Go!#sclient=psy&hl=en&q=ethernet+mtu+definition&aq=f&aqi=&aql=&oq=&gs_rfai=&pbx=1&fp=df5e37d3d2fae155).

nirvana21
December 10th, 2010, 06:13 PM
Layer 2 (Ethernet) where ifconfig sets the MTU size. The MTU you are referring to is the frame size and for Ethernet (see here (http://www.networkingreviews.com/2008/02/29/the-base-of-ip-networks-osi-model/)) it is normally 1500. See here (http://compnetworking.about.com/od/networkprotocols/g/mtu-maximum.htm)for a basic discussion.
That is correct.

Here is a pretty good Google search (http://www.google.com/search?q=tcp+layers&btnG=Go!#sclient=psy&hl=en&q=ethernet+mtu+definition&aq=f&aqi=&aql=&oq=&gs_rfai=&pbx=1&fp=df5e37d3d2fae155).

Thanks for the confirmation.