[libvirt] can't receive keepalive message during migration

Hi, When testing migration, I found a problem that the server can't receive keepalive reply from client when doing migration. The log shows that virsh did send the keepalive reply, but server didn't reveive it. The strange part is it's OK to migrate from host A to Host B, but always fails to migrate from host B to host A. When disable keepalive, migration will success. Any ideas? -- Thanks, Hu Tao