Old network guys remember when networks were not all IP, and there were Novell IPX routers, and AppleTalk routers, and DECnet Phase IV routers, and CLNP lived o

Old network guys remember when networks were not all IP, and there were Novell IPX routers, and AppleTalk routers, and DECnet Phase IV routers, and CLNP lived on for a while due to phone carriers and IS-IS. And even in IP, BGP is only the latest in a long, sad story of routing protocols, and other protocols are usually used inside networks… including IS-IS.