Here is something that I am not sure if I understand:
1) I connected a terminal server which has pre-configured IP=192.168.30.1 to a Cisco switch 2900.
2)When I ping 192.168.30.1 from the Cisco switch, it times out.
3) Then I assigned on the Cisco switch'int vlan 1 = IP 192.168.30.2'.
Then I was able to ping.
I don't understand this though. If the terminal server is already on vlan1, why I was able to ping it only when assiging the IP to the vlan1 interface?
You can only communicate between 2 IP devices when they both have an IP address.
So until you assigned an IP address to vlan 1 then you could not ping the terminal server. And because the 2900 is a L2 switch then the vlan interface that you assign the IP address to has to be in the same vlan as the terminal server, or you need a routing device somewhere to route between the switch and the terminal server.