Set the MTU Value on one or More Ports

You can set the MTU value for an individual port or a set of ports by using the procedure in this section. In the following procedure, ports 0/1, 0/2, and 0/3 are part of the LA. When the MTU of a port in a bundle is different than the MTU for the port channel, the port will not be brought up in the bundle. See LA Topology Example for the topology referenced in this procedure.

1. Review the port state behavior with the default MTU settings for all of the ports.

   SEFOS# show interface mtu
    
   Ex0/1   MTU size is 1500
   Ex0/2   MTU size is 1500
   Ex0/3   MTU size is 1500
   Ex0/4   MTU size is 1500
   Ex0/5   MTU size is 1500
   Ex0/6   MTU size is 1500
   Ex0/7   MTU size is 1500
   Ex0/8   MTU size is 1500
   Ex0/9   MTU size is 1500
   Ex0/10  MTU size is 1500
   Ex0/11  MTU size is 1500
   Ex0/12  MTU size is 1500
   Ex0/13  MTU size is 1500
   Ex0/14  MTU size is 1500
   Ex0/15  MTU size is 1500
   Ex0/16  MTU size is 1500
   Ex0/17  MTU size is 1500
   Ex0/18  MTU size is 1500
   Ex0/19  MTU size is 1500
   Ex0/20  MTU size is 1500
   Ex0/21  MTU size is 1500
   Ex0/22  MTU size is 1500
   Ex0/23  MTU size is 1500
   Ex0/24  MTU size is 1500
   po1     MTU size is 1500
   vlan1   MTU size is 1500

2. Create the interface (0/1 in this example).

   SEFOS# configure terminal
   SEFOS(config)# interface extreme-ethernet 0/1
   SEFOS(config-if)# shutdown

3. Configure the MTU.

   SEFOS(config-if)# mtu 1000
   SEFOS(config-if)# no shutdown
   SEFOS(config-if)# end

4. Review the etherchannel information.

   The output has been truncated for readability.

   SEFOS# show etherchannel detail
    
   ...
                    Ports in the Group
                    ------------------
   Port : Ex0/1
   -------------
   Port State = Down, Not in Bundle
   Channel Group : 1
   Mode : Active
   ...

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   Note - After you configure the MTU value on port 0/1 to 1000, note that because the MTU value on port 0/1 is different than the MTU value of the port channel interface, the extreme-ethernet port, 0/1, in switch A will be brought down and out of the bundle.

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