clapper@nadc.arpa (Brian M. Clapper) (09/01/88)
I am trying to set up a gateway between two LANs, and I'm having some difficulties that my documentation does not address. My LAN consists of two VAXes, both running Ultrix 2.0-1, and a Sun 3/160, running SunOS. They are communicating via an Ethernet. One of the VAXes is also connected to another remote LAN over a dedicated telephone line (using a DMR11). The machines on the Ethernet use a class C addressing scheme. The connection over the phone line uses a class B addressing scheme. A facsimile of my host table follows: # # Local Network # 192.9.200.6 sun 192.9.200.50 vax1 192.9.200.51 vax2 # # Connection to remote network # 130.1.0.50 vax1alias 130.1.0.1 remotevax I'm trying to set up 'vax1' as a gateway, so that I can send mail and connect directly to 'remotevax' from the 'sun' or 'vax2' machines. The Ultrix documentation on networking claims I need a host name on both networks, and that making the host part of the addresses identical will serve to establish a gateway. I chose host number '50' for the 'vax1' machine on both networks, and perpetuated the hosts file across all machines. (I am using NFS and the Yellow Pages Service, so at first I merely update the yellow pages database on the master server. Later, paranoia led me to make the /etc/hosts file identical on all machines, even though common sense told me it wasn't necessary.) When I attempted to connect directly to 'remotevax' from the Sun, the system responded with the message 'network is unreachable'. Then I tried adding an 'arp' entry for the 'vax1' machine to the Sun. (There wasn't one initially.) I tried to connect again, and the connection timed out. I can connect directly from 'vax1' to 'remotevax' with no trouble. Mail also zips back and forth reliably across that link. I cannot, however, set up the gateway. Perhaps I've missed something in the documentation, but I've pored over Sun's meager networking instructions, as well as DEC's more in-depth ones, and I still can't figure it out. What am I missing? Any help at all will be greatly appreciated. Brian M. Clapper ARPA: clapper@nadc.ARPA Code 7031 UUCP: ...!harvard!clapper@nadc.ARPA Naval Air Development Center Street and Jacksonville Roads Phone: (215) 441-2118 Warminster, PA 18974-5000 AUTOVON: 441-2118
mouse@mcgill-vision.UUCP (der Mouse) (09/11/88)
In article <17023@adm.ARPA>, clapper@nadc.arpa (Brian M. Clapper) writes: > I am trying to set up a gateway between two LANs, and I'm having some > difficulties [...]. [Machines are two Ultrix 2.0-1 VAXen and a > Sun-3/160 on class C addressed Ethernet; one VAX has a point-to-point > link with class B adresses.] > [the Ethernet] > 192.9.200.6 sun > 192.9.200.50 vax1 > 192.9.200.51 vax2 > [the p-to-p link] > 130.1.0.50 vax1alias > 130.1.0.1 remotevax > I'm trying to set up 'vax1' as a gateway, In order to make this work, you need: - vax1 needs to be willing to forward packets it receives destined for the "other" network. - remotevax needs to know to send packets for 192.9.200.* to 130.1.0.50. - sun and vax2 need to know to send packets for 130.1.*.* to 192.9.200.50. > When I attempted to connect directly to 'remotevax' from the Sun, the > system responded with the message 'network is unreachable'. Aha. What happens is effectively this. The Sun kernel is handed a packet addressed to 130.1.0.1. It tries to figure out what to do with it. First it looks for a route to 130.1.0.1 explicitly; it doesn't find one. Then it looks for a route to 130.1 and doesn't find that either. Then it looks for a route to 0.0.0.0 (aka "default") and fails there too. Then it refuses to send the packet, with error ENETUNREACH, Network is unreachable. > What am I missing? Routes, most likely. I'd suggest setting up routed on all your machines. (I'd suggest gated, the more modern thing, except that you almost certainly don't have it. And since you clearly aren't connected to the Internet, I don't know any easy way for you to get it.) First though, just to make sure that's the problem: sun# /usr/etc/route add remotevax vax1 1 vax2# /etc/route add remotevax vax1 1 remotevax# /etc/route add sun vax1alias 1 remotevax# /etc/route add vax2 vax1alias 1 and see if it works better. (I think I have /etc and /usr/etc right, but I'm not sure. If they aren't where I suggest, poke around.) If this isn't it, I don't know what's wrong. I'd have to have a closer look. Good luck. der Mouse old: mcgill-vision!mouse new: mouse@larry.mcrcim.mcgill.edu