I assume you are trying to connect using SQL*Plus by doing:
sqlplus yourusername/yourpassword@BX
1) Make sure that there is at least one blank line after the last ")" in your tnsnames.ora. This makes a big difference on some OSes and SQL*Net versions. It is an old problem, but sometimes people still run into it.
2) Make sure that you can reach the target machine. Also check to make sure that your domain names are being resolved correctly.
ping brahma
ping brahma.your.domain.name
ping ip.ad.dr.ss
traceroute brahma
traceroute brahma.your.domain.name
traceroute ip.ad.dr.ss
traceroute is called tracert on the Windows platforms.
3) Try a tnsping: (located in the bin directory in your Oracle directory tree)
tnsping BX
4) If tnsping fails, check to make sure that you can reach port 1521 on brahma:
telnet brahma 1521
telnet brahma.your.domain.name 1521
telnet ip.ad.dr.ss 1521
These should be able to connect, but shouldn't give you any textual response. If you can connect, then the problem is still on the client-side. If you can't connect, then your problem is really network related or the server's Listener is not accessible.
-- Michael
Darkstreak Consulting
www.darkstreak.com