Configuring Ethernet Interfaces
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adjacent if their MTU sizes do not match. You should ensure that the MTU on
the device at the far end of the Ethernet connection is using the same MTU as
the interface you are configuring.
If routers and switches have different MTU sizes in a TCP/IP network, trans-
missions and routing may be affected. For example, if a switch has a smaller
MTU and your router sends a frame that exceeds that size, the switch will
fragment the frame. If the forwarded frame is tagged with the "do not frag-
ment" field, then the switch cannot send the frame onto its destination. In this
case, the switch must return an Internet Control Message Protocol (ICMP)
message to notify the router that the frame cannot be fragmented. The router,
in turn, must send the packet back to the originator, and the originator must
remove the "do not fragment" field and resend the frame. If possible, you
should ensure that the switches and routers on your network are using the
The MTU size refers to the Ethernet payload.
To change this setting, enter:
Syntax: mtu <size>
Replace <size> with a number between 64 and 1500.
Adding a Description
You can add a description to the interface if you want to document information
about it. For example, you might want to use a description to differentiate
between the two Ethernet interfaces: you could document which LAN seg-
ment connects to each interface. You might also want to use a description if
you have had to troubleshoot a problem and want to document why you
changed a particular setting.
Syntax: description <line>
Replace <line> with up to 80 characters. For example, you might enter:
ProCurve(config-eth 0/1)# description Attached to building 1
The description you enter is displayed only when you enter the following
command from the enable mode context:
ProCurve# show running-config