Description

This test is intended to test test the function of jumbo frame support

How to test

determine the nicmodel of the guest: nicmodel
determine the max frame length supported by the nicmodel: max_frame_length (mtu)
determine the max icmp packet length support by the nic_model: _max_icmp_packet_size = max_frame_length
packet_size = [ 0, 1, 48, 64, 512, 1440, 1500, 1505, 4096, 4192, 32767, 65507 ]
start the virtual machine with interface name of IFNAME

determine the bridge whcih IFNAME is connected: bridge

qemu-kvm -net nic,model=nicmodel,macaddr={macaddr},ifname=IFNAME -net tap ...

change the MTU of the tap device in the host
```
ifconfig IFNAME mtu 65521
```
change the MTU of the ethernet device in the guest
```
ifconfig eth0 mtu _max_frame_length_
```
if needed, add a dedicated route entry in the host [Resolution]
```
route add guest_ip IFNAME
```
if needed, add an static entry for guest nic
```
arp -s guest_ip guest_mac
```
ping the guest in the host with path mtu discovery
```
ping -M do guest_ip -s max_icmp_packet_size -c 10
```
check the packet loss ratio, if the ratio is not zero, fail the whole cases.

execute the following script in the guest

while true; do ifconfig eth0 mtu 1500; ifconfig eth0 mtu max_fram_length done

and in the same time flood ping the guest in the host for five minutes:
```
ping -f -s max_icmp_packet_size
```
ping the guest in the host and see if the packet loss ratio is zero, if not, fail the whole case
```
ping -c 2 guest_ip 
```
restore the mtu
```
ifconfig eth0 mtu 1500
```