Xen networking fails with error "Error: either "dev" is duplicate, or "1500" is a garbage."

Issue

• Xen networking fails with the below error message after upgrading to xen-3.0.3-132.el5_7.2. Bridges are not getting created properly to enable networking to guests.

  net.bridge.bridge-nf-call-arptables = 0
  net.bridge.bridge-nf-call-ip6tables = 0
  net.bridge.bridge-nf-call-iptables = 0
  Error: either "dev" is duplicate, or "1500" is a garbage.
  

Reverting xen and xen-libs packages to the versions which were previously installed resolves this issue.

Below script is used to enable networking to guests which creates multiple bridges on the host as per Xen_networking-Configuring_multiple_guest_network_bridges_to_use_multiple_Ethernet_cards

#!/bin/sh
# network-xen-multi-bridge
# Exit if anything goes wrong.
set -e
# First arg is the operation.
OP=$1
shift
script=/etc/xen/scripts/network-bridge.xen
case ${OP} in
start)
     $script start vifnum=1 bridge=xenbr1 netdev=eth1
     $script start vifnum=0 bridge=xenbr0 netdev=eth0
     ;;
stop)
     $script stop vifnum=1 bridge=xenbr1 netdev=eth1
     $script stop vifnum=0 bridge=xenbr0 netdev=eth0
     ;;
status)
     $script status vifnum=1 bridge=xenbr1 netdev=eth1
     $script status vifnum=0 bridge=xenbr0 netdev=eth0
     ;;
*)
     echo 'Unknown command: ' ${OP}
     echo 'Valid commands are: start, stop, status'
     exit 1
esac