2960x configure IP mtu?

[silver64317]

i got an old switch - 2960x and am trying to configure the routing MTU on it to make the vlan routing use jumbo frame.

however, the document https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/int_hw_components/configuration_guide/b_int_152ex_2960-x_cg/b_int_152ex_2960-x_cg_chapter_0110.html only mentioned about the general MTU settings not IP MTU.

I can set the MTU to 9000 on the giga ethernet ports via commandline "system mtu jumbo 9000" but i can't set the ip mtu to 9000.

Does anyone know why?

is it possible to set IP mtu to jumbo for the vlan routing on 2960x?

thanks in advance

[marce1000]

                   >but i can't set the ip mtu to 9000

  - Which command, did you try ? Which error did you get ?

 M.

[silver64317]

hi,

the SW version of thsi 2960x is 15.2(2)E3 , quite old I guess.

i tried command "system mtu" but only the "jumbo" cmd or mtu size are prompted, as shown in figure below.

this is the only mtu settings i can get for now.

tried commandline such as "system ip routing mtu", "system ip mtu", "system routing mtu"...etc but all failed.

can anyone help?

[marce1000]

                     - Did you also try ip mtu... , (without system).

 M.

[balaji.bandi]

The switch does not support the MTU on a per-interface basis.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/15-2_2_e/configuration/guide/b_1522e_2960_2960c_2960s_2960sf_2960p_cg/b_1522e_2960_2960c_2960s_2960sf_2960p_cg_chapter_01001.html

[silver64317]

@marce1000hi,

unfortunately this "ip mtu" didn't work at all. the subcommands of ip config does not include "mtu", as shown in figure below:

@balaji.bandiHi,

does this document imply that the VLAN routing mtu cannot be changed?

can't find the correct command to edit it...

[Reza Sharifi]

The switch is layer-2 and so only the system MTU command should work:

try:

system mtu jumbo 9000

or

system mtu jumbo 7500

HTH

[balaji.bandi]

SUMMARY STEPS

1. enable
2. configure terminal
3. system mtu bytes
4. system mtu jumbo bytes
5. end
6. copy running-config startup-config
7. show system mtu

[Joseph W. Doherty]

Possibly that's because at L2 there's no IP, since IP is L3.

However, if L2 MTU is jumbo size, IP should be able to have larger packets (that correspond to the L2 MTU).