It's for routing convenience more than anything else. grouping together 3 nodes is MUCH simpler than grouping together 4. groups of 3 are also more efficient for finding the shortest paths through the network.
also i changed the unused bit pair to be 11 instead of 00. For now, a packet with a 11 in any of the address fields will just be ignored. The first router that the packet hits will just send a ping back as if it was handled correctly, but nothing will have been sent further than that router.
also i changed the unused bit pair to be 11 instead of 00. For now, a packet with a 11 in any of the address fields will just be ignored. The first router that the packet hits will just send a ping back as if it was handled correctly, but nothing will have been sent further than that router.