Opkg unknown package openvswitch

I am using TP LINK WR1043N V5 router. I want to use this as OpenvSwitch to connect with RYU controller.

The problem is that opkg is unable to install openvswitch package as it says "unknown package openvswitch".
An interesting thing is that I was able to install openvswitch on the router successfully, but after we reset the router due to some reason, we wern't abe to install the openvswitch package again.
Note that all other packages are being able to install as usual (Luci)

Please Help.

I have flashed the router with SNAPSHOT of OpenWRT available for this hardware which is :
Firmware OpenWrt snapshot Install URL: http://downloads.openwrt.org/snapshots/targets/ar71xx/generic/openwrt-ar71xx-generic-tl-wr1043n-v5-squashfs-factory.binFirmware
OpenWrt snapshot Upgrade URL: http://downloads.openwrt.org/snapshots/targets/ar71xx/generic/openwrt-ar71xx-generic-tl-wr1043n-v5-squashfs-sysupgrade.bin