we have connected 2 routers with serial link and configured OSPFv2 on them , the routers have established neighbourship On the way of establishing adjacency the routers when in the EXSTART stage select the master and slave routers. Now why is that on...

When we configure ether channels on switches the ports are shown up at layer 1 and layer 2. So how does it prevents formation of loop in ports at physical layer in case if the packet comes back. The  spanning tree thinks it as a single bridge port.