Dear Mr. Liu,
  There are some descriptions in 
dpdk-16.11\doc\guides\sample_app_ug\vhost.rst,
"The sample application performs simple packet switching between virtual 
machines based on Media Access Control (MAC) address or Virtual Local Area 

Network (VLAN) tag." So, we runned the vhost-switch sample in a VM with 
three
virtio ports. First, we binded one virtio port to igb_uio. Then we runned 
the command
"./vhost-switch -c f -n 4 --socket-mem 1024 -- --socket-file /tmp/sock0 
¨C-vm2vm 1 ¨C-dequeue-zero-copy"
And then error occured. We found that the 'dev_info.max_vmdq_pools' of the 
virtio
port was 0, and division by zero error occured at the statement 
'queues_per_pool = dev_info.vmdq_queue_num / dev_info.max_vmdq_pools;'
We fixed this by assigning 'queues_per_pool' to 0 if 
'dev_info.max_vmdq_pools'
was 0, but there were still other errors when running vhost-switch. 
  So, we doubted whether we use the vhost-switch in a wrong way. Could you
please give us some advice that how to use the vhost-switch between two or 
more
 VMs?
  I look forward to hearing from you.

 Yours faithfully,
 Yong Wang