How to change MTU on Cisco

I will give an example of increasing MTU on Cisco switches.

Let’s look at the current configuration, the names of the necessary interfaces and go to the configuration mode:

show running-config
configure t

Let’s say that traffic with an MTU of more than 1500 can go between two ports, select the first port and increase the MTU:

interface GigabitEthernet2/24
mtu 9216

Then we increase the MTU on the other port:

interface TenGigabitEthernet3/3
mtu 9216

For example, I indicated the MTU of 9216 bytes, since I had a Cisco 6509E at hand in which you can specify only such an MTU size, to check which size you can specify, run the command:

mtu ?

For example, to test MTU with ping packets, run the command in Linux:

ping -M do -s 8000 192.168.5.5

Don’t forget to increase the MTU on the network interface:

ifconfig
ifconfig eno1
sudo ifconfig eno1 mtu 9000

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