Change KVM VM's network packet size (MTU)

change_virbr_mtu.sh

#! /bin/bash

# Reference(s):
# https://libvirt.org/sources/virshcmdref/html/sect-net-edit.html

# 1. get information of virtual bridge (virbr*)
sudo virsh net-list --all

# 2. edit virbr mtu
sudo virsh net-edit <virbr connection name>

# append or insert the below item next to <bridge ~/>
# <mtu size='9000'/> and :wq

# 3. reboot and change mtu on guest

# 4. get virbr information
ifconfig <virbr*>
# virbr*: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9000

# 5. get mtu working status
tracepath <host>
# 1?: [LOCALHOST]                                         pmtu 9000