Read from net connection return header, body and error.

ReadJSON wraps Read with json decoder.

Write to net connection cmd: header.cmd body: payload.

WriteJSON wraps Write with json encoder.

controller tell edge that new edge join.

add route.

alarm report.

controller tell edge that edge leave.

del route.

heartbeat between controller and edge.

edge register to controller.

edge report subhost of it to controller.

controller deploy route added to edges.

broadcase edge offline once edge keepalive faile controller will broadcase edge offline msg to all online edges.

broadcast edge online once edge register success controller will broadcast edge online msg to all online edges.

edge information.

reply for edge register req.

edge register req.

edge report host edge report host information to controller controller get topology host1 host1' \ / edge1 ---- edge2 / \ host2 host2' .

controller deploy route deleted to edges.

version: 1byte cmd: 1byte body len: 2bytes.