***Telnet Terminal Services***
The Telnet protocol is an application layer protocol in the TCP/IP protocol suite. It supports remote login and virtual terminal services through the TCP connections. The S-switch provides the following Telnet services.
Telnet Server :
By default, the S-switch functions as the Telnet server. The Telnet client program can be run on the user terminal, as shown in Figure 1.
Figure 1 S-switch providing the Telnet server service
Users can log in to the S-switch through Telnet to configure and manage the S-switch. If the user logs in to the S-switch through the Layer 2 switch, the IP addresses of the PC and the S-switch must be in the same network segment. In addition, the Layer 2 switch and the S-switch must belong to the same Virtual Local Area Network (VLAN).
An S-switch functions as the Telnet client to initiate a connection and a router or an application server functions as the Telnet server, as shown in Figure 2.
Figure 2 S-switch providing the Telnet client service
If the S-switch logs in to the router through Telnet to configure and manage the router, the IP addresses of the S-switch and the router must be in the same network segment. If the S-switch logs in to the application server through Telnet to configure and manage the server, the IP addresses of the S-switch and the router must be in the same network segment and can interconnect at the network layer.
Cascading Telnet Server:
The S-switch can function as either the client or the server.
Figure 3 S-switch providing cascading Telnet service
S-switch-A logs in to S-switch-B through Telnet. Then, S-switch-B logs in to S-switch-C through Telnet. In this manner, the three S-switches form a cascading login structure. Here, S-switch-A is the client of S-switch-B, and S-switch-B is the client of S-switch-C.
S-switch-A and S-switch-B are required to belong to the same VLAN, and their IP addresses should be in the same network segment. This is the same with S-switch-B and S-switch-C.