Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!lll-tis!lll-winken!uunet!munnari!ditmela!smart From: smart@ditmela.oz (Robert Smart) Newsgroups: comp.protocols.tcp-ip Subject: Multi-protocol wide area networks. Message-ID: <1835@ditmela.oz> Date: 23 Jul 88 13:36:29 GMT Reply-To: smart@ditmelb.oz.au (Robert Smart) Organization: CSIRO, Division of Information Technology, Australia Lines: 85 We are in learning mode about creating wide area networks. The shortage of good solutions is shown by the NORDUNET plan. They are going to create a wide area ethernet (via mac-level bridges) with no hosts on it, only routers for mid-level protocols like IP and DECNET plus funny boxes for connecting serial lines through an ethernet! Let me say what I think is available today, and why it is deficient for what we would like to do. Cisco and Proteon provide boxes which will route IP and DECNET (and other protocols of no interest to us) between ethernets. They claim they will soon support OSI Connectionless Network routing as well. I know a little about Proteon P4200s, and assume Ciscos are the same: the boxes can have ethernet boards and serial line boards. However the serial lines can only speak the secret Proteon protocol: so they have to lead to another Proteon box. The first problem with this is that not all points on your network can justify a proteon box. If you have a small site with just a few Suns or VMS Vaxes then you will want to connect them to the world by just running slip out of one of the Suns or Asynch or Synch decnet out of one of the VAXes. It would be nice to be able to run these serial lines into a Proteon box serial port instead of having to run them into some host on your ethernet. The whole point of getting Proteon boxes is to avoid having hosts doing packet routing. Another protocol we would like to support is X.25. It would be nice to allow two Proteon boxes to be able to talk to each other over X.25. Presumably this would be used as a backup mechanism for connection when a leased line malfunctions. But it could also be used as the normal method of moving packets between networks that don't have a lot to say to each other. Once again there are standards for running IP and DECNET over X.25. It would be nice to be able to run connections from isolated IP or DECNET nodes into a Proteon box via an X.25 virtual circuit instead of having to run them through another host. However we would also like to be able to have our router network act as an X.25 network. I.e. host1 can talk X.25 to host2 in: X.25 connection private protocol X.25 host1---------------router----------------router-------host2 Why would you want to do this? Well firstly there are plenty of implementations now that will run OSI over X.25, so it is a natural way to get OSI protocols now. Conversely it is not obvious when there will be host implementations of Connectionless, or routing software that will allow implementations of X.400 (say) over CLN to talk to implementations connected to X.25 networks around the world. Also there is a lot of software around that runs over raw X.25 (or via non-standard mid-level protocols): such as the Coloured Book suite. There are now protocols for running X.25 packets over ethernet (pinkbook), and over DECNET (PSI-access) and now also over TCP/IP. We would, of course, like our X.25 implementation to talk happily with these. Another thing that would be useful would be to have our routers connect arbitrary synchronous lines. sync line----router------------router----sync line continues This would allow for connecting IBM and other things through the network. Obviously a sync packet entering one end should not be unduly delayed before emerging from the other: these packets would have to have priority. For longish packets it might well be important to arrange for them to start emerging from the far end before they have even finished arriving at the receiving end. In which case you better arrange to get the rest to the far end in time! It would also be nice if the router would act as a mac level bridge for some or all protocols it doesn't really know about. I gather from the nordunet proposal that this is coming. Well, while we're at it. It would be nice to be able to use the serial ports as a serial line concentrator. Users logging in to these ports could be connected to their destination in many ways: telnet, rlogin, X.29, OSI VT, or just by connecting to another port somewhere. And if it was done nicely the user need not even be aware of how the connection is being made. Protocol transparency: never quite comes off in real life. Would any of the router makers like to comment on these proposals. All pie-in-the-sky? Is the NORDUNET wide area ethernet really the only way? Bob Smart or