Path: utzoo!utgpu!watserv1!watmath!att!att!linac!uwm.edu!bionet!hayes.ims.alaska.edu!accuvax.nwu.edu!casbah.acns.nwu.edu!jln From: jln@casbah.acns.nwu.edu (John Norstad) Newsgroups: comp.protocols.appletalk Subject: Re: One way AppleTalk? Message-ID: <858@casbah.acns.nwu.edu> Date: 3 Nov 90 03:07:15 GMT References: <1990Nov2.001254.12845@swbatl.sbc.com> Sender: news@casbah.acns.nwu.edu Organization: Northwestern University Lines: 97 In article <1990Nov2.001254.12845@swbatl.sbc.com> george@swbatl.sbc.com (George Nincehelser 5-6544) writes: > I've run across a strange problem with our company's AppleTalk networks. > I've got a guy installing a Shiva Fastpath 4 several states away who is > having problems seeing devices within certain zones that are local to me. > He sees the zone names, but he can't see any devices in them. We've used > InterPoll to confirm this (scanning for several minutes). > > We are running a Phase 1 network. Very interesting. I'm currently struggling with similar problems, only in my case all my FastPath 4 boxes work fine. Instead, I'm having this same problem with Shiva NetBridges, a TurboBridge, and IPTalk/atalkad-tunneled Gatorboxes! As an example, I'll discuss a Shiva NetBridge case. Here's a picture of part of our large campus AppleTalk Internet (we have about 40 nets and 27 zones total in our Internet). All of the nets in this picture are LocalTalk. (For best results, view this picture using a monospace font!) /------------------/ net A /-----------------/ net B | | Shiva NetBridge Hayes InterBridge | | /---------------------------------------------------------/ net C | Hayes InterBridge | /-----------------------------/ net D | Shiva FastPath 4 | ... IPTalk Tunnel | Shiva FastPath 4 | /---------------------/ net E All 27 zone names appear properly in the Chooser on Macs on net A, but nothing can be found inside some of the zones (in either the Chooser or with Interpol). I'll call such zones "empty." In particular, in the diagram above, the zones for nets B and D are empty, while the zones for nets C and E are normal (non-empty). It's interesting that the empty zones are exactly the ones whose nets are immediately "behind" a Hayes InterBridge from net A's point of view. Zones whose nets are immediately "behind" other kinds of routers are normal. This is true not only in the small picture I've presented above, but throughout our complete Internet - there are about 10 empty zones behind InterBridges total from the point of view of Macs on net A. It's also interesting that net D is empty, while net E is normal, since traffic from net A must pass through net D to reach net E. So net A can see "through" net D, even though is can't see "in" net D. I examined the routing and zone information tables inside both the NetBridge and the InterBridge connecting nets B and C. Both were perfectly normal - correct network numbers, next router fields, hop counts, status, and zone names for all of our zones and nets. So it appears that the routers are communicating with each other using RTMP and ZIP correctly. In particular, the NetBridge's routing table entry for net B correctly pointed to the InterBridge joining nets B and C, with a hop count of 1, status "good", and the proper zone name in the ZIT. Similarly, the InterBridge's routing table entry for net A correctly pointed to the NetBridge with a hop count of 1, status "good", and the proper zone name in the ZIT. The problem is not symmetric: All the other nets on campus can see devices inside net A just fine. We're using phase 1 also. No phase 2 is involved anywhere here. I checked, and as far as I can tell I have NOT enabled any zone "hiding" or "filtering" options in any of my routers, and all of my routers are configured to do phase 1 routing, not phase 2. There must be something going wrong with the NBP Broadcast Request and zone-wide NBP Lookup broadcast mechanisms used to locate devices in zones. I wish I had a LocalTalk protocol analyzer to investigate this problem in more detail, but I don't (we have one on order). It's interesting that we're having this same problem with two different new Shiva NetBridges on campus (ROM v2.01). A third older Shiva NetBridge (ROM v1.02) on campus in a similar configuration works just fine! My problems with Gatorboxes and the TurboBridge are similar but not identical. They also involve this "empty zone" phenomenon. Has anybody else ever experienced this kind of problem? What can cause it? It's a mystery to me right now. I have a natural suspicion that my problems are all related and may have a common cause, but I have no idea what that cause might be. It is also possible that there is no common cause, and I really have three separate problems. John Norstad Academic Computing and Network Services Northwestern University jln@casbah.acns.nwu.edu