Trace of Access Attempts
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From the following network trace, you can see a problem with the Apple Internet Routers on the network. However, the actual problem is with the AppleTalk stack, not with the Apple Internet Router code. This problem happens with other AppleTalk based services also, and is not exclusive to the AWS 95.
The problem can be see early in the trace in packets 3 - 10.
Packet 3 is an RTMP broadcast from Router 1
Packet 4 is an NBP LkUp from Router 2 requested by the end node
Packet 5 is an NBP Repl sent to Router 1
Packet 6 is the forwarded packet from Router 1 to Router 2
Packet 7 is an NBP LkUp from Router 2 requested by the end node
Packet 8 is an NBP Repl sent to Router 1
Packet 9 is the forwarded packet from Router 1 to Router 2
Packet 10 is an echo packet sent from Router 2 to the Ethernet address of Router 1 with the AppleTalk address of the AWS 95
Here Router 1 looks at the packet and determines it is not its packet. Since there is no need to forward it, the packet is dropped.
The problem is with the Address Mapping Table (AMT) in Router 2 that has gotten an erroneous entry in its cache. The problem occurred when the Server responded to Router 1 and Router 1 forwarded the Packet to Router 2. At which point Router 2 cached the AppleTalk address of the Server with the Ethernet address of Router 1.
Workaround
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The workaround is to install the Network Software Installer (NSI) 1.5 on the Macintosh computers that are running the Apple Internet Router software. You might also want to consider moving the server behind a router; in other words to a segment of the network with only one router. If you do this, be sure the router is fast enough to handle the traffic to and from the server.
This article was published in the "Information Alley":
Volume II, Issue 3, Page 10
Article Change History:
31 May 1995 - Added Info Alley information; made minor udpates.
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