[PVE-User] connectivity fail from KVM guest. Proxmox 2.1

[Muhammad Yousuf Khan]

i just install Proxmox 2.1 on debian OS 6.0.5 squeeze for testing
purpose, everything went well from creating vm to XP guest
installation however at the end i can not make my gust OS (win XP) to
communicate with other VMs running on 1.9 or other physical machines.
when i ping it gives me request timed out. here is the setting.

cores: 1
ide0: data:100/vm-100-disk-1.raw,size=15G
ide2: local:iso/xp2006.ISO,media=cdrom,size=626784K
memory: 512
name: test
net0: rtl8139=6E:CD:16:67:D9:3C,bridge=vmbr0,tag=1
ostype: wxp
sockets: 1

i am following this document for preparing the base machine
http://pve.proxmox.com/wiki/Install_Proxmox_VE_on_Debian_Squeeze

Thanks,