Description of problem:
When run vlan test in the guests, After configure by vconfig command, 802.1q vlan on guest with rtl8139 nic doesn't effect.
Vlan test the 802.1q vlan function of nic(rtl8139/e1000/virtio) on guest, testing steps:
    1) Create two VMs with rtl8139/e1000/virtio nic
    2) Setup guests in different vlan by vconfig and test communication by ping using hard-coded ip address
    3) Setup guests in same vlan and test communication by ping
    4) Recover the vlan config

Version-Release number of selected component (if applicable):
etherboot-zroms-kvm-5.4.4-10.el5
kmod-kvm-83-105.el5
kvm-83-105.el5
kvm-tools-83-105.el5
kvm-qemu-img.83-105.el5
kvm-debuginfo-83-105.el5

How reproducible:
100%

Steps to Reproduce:
1.Boot two VMs with rtl8139 nic on host

2.Setup guests in different vlan by vconfig and test communication by ping using hard-coded ip address
On guest1:
#vconfig add eth0 10
#ifconfig eth0.10 192.168.123.11
On guest2:
#vconfig add eth0 20
#ifconfig eth0.20 192.168.123.12
#ping 192.168.123.11

3.Setup guests in same vlan and test communication by ping
On guest1:
#vconfig add eth0 10
#ifconfig eth0.10 192.168.123.11
On guest2:
#vconfig add eth0 10
#ifconfig eth0.10 192.168.123.12
#ping 192.168.123.11

  
Actual results:
Guest is unexpectedly pingable in different vlan


Expected results:
1. guests in different vlan can't ping successfully
2. guests in same valn can ping successfully

Additional info:
1. qemu-kvm command line:
/home/amos/Project/multi/kvm-autotest/client/tests/kvm_runtest_2/qemu -name 'vm1' -monitor tcp:0:5400,server,nowait -drive file=/home/amos/Project/multi/kvm-autotest/client/tests/kvm_runtest_2/images/RHEL-Server-5.3-64.0.qcow2,if=ide,boot=on -net nic,vlan=0,macaddr=00:11:22:33:8D:01,model=rtl8139 -net tap,vlan=0,ifname=rtl8139,script=/etc/qemu-ifup-switch,downscript=no -m 512 -usbdevice tablet -rtc-td-hack -no-hpet -cpu qemu64,+sse2 -smp 1 -vnc :0
/home/amos/Project/multi/kvm-autotest/client/tests/kvm_runtest_2/qemu -name 'vm2' -monitor tcp:0:5401,server,nowait -drive file=/home/amos/Project/multi/kvm-autotest/client/tests/kvm_runtest_2/images/RHEL-Server-5.3-64.0.qcow2,if=ide,boot=on -net nic,vlan=0,macaddr=00:11:22:33:8D:02,model=rtl8139 -net tap,vlan=0,ifname=tap_rtl8139_2,script=/etc/qemu-ifup-switch,downscript=no -m 512 -usbdevice tablet -rtc-td-hack -no-hpet -cpu qemu64,+sse2 -smp 1 -vnc :1
2.cpuinfo: Intel(R) Core(TM)2 Quad CPU    Q9400  @ 2.66GHz
3.network status
[root@dhcp-66-70-53 staf-kvm]# brctl show
bridge name bridge id  STP enabled interfaces
switch  8000.0023ae8ff38d no  tap_rtl8139
                              tap_rtl8139_2
                              eth0
virbr0  8000.000000000000 yes