Head scratching with SQL*Net V2

The local setup is we have a Oracle server and 2 client machines all running 7.1.4, the connections are set up with tnsnames.ora and listener.ora for SQL*Net V2 communications over tcp/ip. There's only 1 instance on the server.

Yesterday, the dba added another instance on the server and added the appropriate entries in tnsnames.ora and listener.ora to make it accessible over the net. On client1, things work just as intended, on client2 we can not connect to the new instance (but the old instance works fine). The error code is ORA-12203 or sometimes ORA-12535.

The server configuration seems ok because we can access both instances from client1. The client tnsnames.ora on client2 seems to be ok too because it can access the original instance just fine. We stripped the tnsnames.ora down to just one entry for the original instance, made sure it works and made sure that's the one being used by forcing TNS_ADMIN environment variable. After that, we simply changed the SID name in the tnsnames.ora to the new instance to make sure there's nothing wrong with the entry. That still gave us the same results.

We're stumped, any suggestions on what we might have missed?

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Viet Hoang
Lucent Technologies/ISSC
vhoang_at_lucent.com