Who will pay for it though? I doubt Ethiopia is in a condition to build a large wall to keep them out. They seem to be the ones that really have problems with Somalis when it comes to a proper border.
I heard that China is having $3 trillion worth of forex reserves. Perhaps China can help Ethiopia. In return, Ethiopia can permit Chinese resettlement in the eastern Ogaden region, which is mostly populated by the ethnic Somalis.
Ogaden is disputed territory with Somalia, right? I believe there are other self-declared republics in Somalia - Puntland and the more successful Somaliland. Maybe Ethiopia would only build a wall on the border with Puntland and what's left of Somalia? They use Somaliland's port, Berbera, to gain access to the Gulf of Aden and the Red Sea.
I remember reading years ago that China is funding railroads in Ethiopia, I wonder what they'll be asking in return. Ethiopia sorely need those since it was left without sea access when Eritrea split away.
According to the latest census, more than 97% of the population in Ogaden is composed of ethnic Somalis. Ethiopia is a Christian dominated states, and the Muslim Somalis don't want Ogaden to remain as a part of that country. Now there are two choices. The first one is to merge Ogaden with Somalia. The second option is to expel the Somalis, and then resettle the region with Christians.