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[Enterprise SONiC] MTU (Maximum Transmission Unit) Follow

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andyyl_chen 陳英倫
  • Updated

Tested model & firmware version:

  • Switch model name:

       AS7326-56X

  • Edgecore SONiC version: 

202006.4

202012.2

202111.0 ~ 202111.3

Restriction:

  • Known issue:
    • It does not return failed if configure over-limit MTU size by SONIC-CLI, and the container will crash.(After 202012.2, we add the error handling for MTU configuration on SONIC-CLI.)

e.g: configure MTU 16000 on the interface.

admin@sonic:~$ show interface status Ethernet0
  Interface    Lanes    Speed    MTU    FEC          Alias    Vlan    Oper    Admin            Type    Asym PFC
-----------  -------  -------  -----  -----  -------------  ------  ------  -------  --------------  ----------
  Ethernet0        1      10G  16000   none  Eth1/1(Port1)  routed      up       up SFP/SFP+/SFP28         N/A
  • Default setting:
    • MTU is 9100 by default
    • MTU range is 1500 to 9216.
  • Currently modifying VLAN's MTU is unsupported; changing interface's MTU may disrupt VLAN-based sessions (e.g., MC-LAG).

Procedure :

Step 1. Configure MTU 4000 on Ethernet0.

Example: MTU of Ethernet0 is 4000

admin@sonic:~$ sudo config interface mtu Ethernet0 4000

Step 2. Save the configuration to config_db.json

admin@sonic:~$ sudo config save -y

Step 3. Check MTU parameter

by SONiC show command.

admin@sonic:~$ show interfaces status Ethernet0
  Interface        Lanes    Speed    MTU    FEC    Alias    Vlan    Oper    Admin            Type    Asym PFC
-----------  -----------  -------  -----  -----  -------  ------  ------  -------  --------------  ----------
  Ethernet0            1      10G   4000    N/A   Eth1/1  routed    down       up             N/A         N/A

 

 

MTU with PortChannel

 

  • Edgecore SONiC version: 

202111.2 ~ 202111.3

Restriction:

  • Known issue:
    Before the 202111.2 version, the PortChannel can not configure MTU by sonic command

Procedure :

Step 1. Configure MTU 4000 on PortChannel01.

Example: MTU of PortChannel01 is 4000

admin@sonic:~$ sudo config interface mtu PortChannel01 4000

Step 2. Save the configuration to config_db.json

admin@sonic:~$ sudo config save -y

Step 3. Check MTU parameter

by SONiC show command.

admin@sonic:~$ show inter status PortChannel01
    Interface    Lanes    Speed    MTU    Oper FEC    Alias    Vlan    Oper    Admin    Type    Asym PFC    Oper Speed
-------------  -------  -------  -----  ----------  -------  ------  ------  -------  ------  ----------  ------------
PortChannel01      N/A     100G   4000         N/A      N/A  routed      up       up     N/A         N/A          100G

 

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