Core Issue
Cisco IOS Software only allows a limited number of Telnet sessions. The router could already be at its capacity for Telnet sessions or could not be configured to accept any Telnet sessions.
Resolution
To resolve this issue, perform these steps:
- Establish a console session.
- Issue the show line command. This verifies whether the maximum number of
VTY lines are already in use, as shown in this example:router#show line
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
* 0 CTY - - - - - 0 1 0/0 -
65 AUX 9600/9600 - - - - - 0 0 0/0 -
* 66 VTY - - - - - 2 0 0/0 -
* 67 VTY - - - - - 2 0 0/0 -
68 VTY - - - - - 0 0 0/0 -
69 VTY - - - - - 0 0 0/0 -
70 VTY - - - - - 0 0 0/0 -
The VTY lines with asterisks are in use. Two VTY lines are in use, and three others are available.
- Disconnect an existing Telnet session by issuing the clear line line-number command.
- If this does not help, the router may not be configured to accept Telnet sessions. Cisco routers do not accept incoming network connections to asynchronous ports (TTY lines) by default.
You must specify an incoming transport protocol or specify the transport input all command before the line accepts incoming connections.
If you are using your router as a terminal server to make console-port connections to routers or other devices, you will not be able to use Telnet to connect to these devices.
For more information about the transport input all command, refer to the transport input section of translate lat.
When Problem Occurs
Continuously
Intermittent
