On 6/29/2012 7:39 PM, Peter Coghlan wrote: The Cisco DECnet configuration guide can be found at: http://www.cisco.com/en/US/docs/ios/decnet/configuration/guide/configuring_… Thanks. I've downloaded it and had a look through it. Let's assume the most usual conflict is at hand, where two different ogranisations use area 1, but neither the networks nor the areas can be merged, but the organisations need to communicate using DECnet. Organisation A applies in the router the DECnet map for Organisation B where the B's real area 1 is chosen to have a virtual area of 24 (which is not used in either networks). Then B assignes a virtual area of 25 to the A's real area 1. Then they configure their routers to use DECnet map and the result looks like: A Cisco ATG B 1.1 -----------------> 24.1 --------------------------------> 1.1 1.2 -----------------> 24.2 --------------------------------> 1.2 1.3 -----------------> 24.3 --------------------------------> 1.3 1.4 -----------------> 24.4 --------------------------------> 1.4 And in the opposite direction it looks like: A 1.1 <------------------ 25.1 <-------------------------------- 1.1 1.2 <------------------ 25.2 <-------------------------------- 1.2 1.3 <------------------ 25.3 <-------------------------------- 1.3 1.4 <------------------ 25.4 <-------------------------------- 1.4 If there aren't any other conflicting areas, all other areas can be routed normally. That seems straightforward enough. I could set up a test with you. Thanks. However... The commands available seem to suggest an individual mapping is required for every host. Is it also possible to map a whole area with a single mapping? It didn't use to be, but the manual says it should be possible on some release 12's but not all. My poor old IGS has version 10.0(6) so it doesn't appear I would be able to map whole areas. The manual seems to say that no communication is possible between the two networks unless mapping entries exist for each of the hosts that want to communicate. This suggests I would need a mapping entry for every host on HECnet and every host on the other network. I think that would probably be too difficult to maintain and might not even fit in the NVRAM. Maybe someone with a later version of IOS might like to try? Regards, Peter Coghlan. I could definitely give this a go. I'm running latest 12.4 on my 1841. -brian