Re : Configuring a terminal server on a 2821 router .....

Unanswered Question
Jul 7th, 2008


I am configuring a 2821 router as a terminal server but somehow I could not access the console ports on the router. In this case, on R1.

Below are the basic configuration on the 2811 as the access router.


ip host R1 2001


interface Loopback1

ip address



line con 0

transport input all

line 1 16



When I try connecting to the R1 router from the access-server, I get

the error message 'remote host refused connection'.

Has anyone encountered any similar issues like this before ?

Pls advice,

- sn -

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
purohit_810 Wed, 07/09/2008 - 20:07

Troubleshooting Procedure

Follow these instructions to troubleshoot your configuration.

If you cannot connect to the router of your choice with a name configured in the ip host command check:

Check whether the port address is configured correctly.

Verify whether the address (interface) used for the reverse Telnet is up/up. The output of the show ip interface brief command provides this information. Cisco recommends you to use loopbacks because they are always up.

Ensure that you have the correct type of cabling. For example, you must not use a crossover cable to extend the length. Refer to the Cabling section for more information.

Establish a Telnet connection to the IP address port to test direct connectivity. You must telnet from both an external device and the terminal server. For example, telnet 2003.

Ensure that you have the transport input telnet command under the line for the target device. The target device is the device that is connected to the terminal server.

Use a PC/dumb terminal to connect directly to the console of the target router. The target router is the device connected to the terminal server. This step helps you identify the presence of a port issue.

If you are disconnected, check timeouts. You can remove or adjust timeouts.

Note: If you encounter authentication failures, remember that the terminal server performs the first authentication (if configured), while the device to which you try to connect performs the second authentication (if configured). Verify whether AAA is configured correctly on both the terminal server and the connecting device.

More Link:


Dharmesh Purohit

sanjaynadarajah Wed, 07/09/2008 - 23:17

Hi Dharmesh,

Well I have used the URL above but it is not for 2811's. When we use 2811 as terminal servers, we need to add the following for the asynchronous line configuration ...

int group async 0

encapsulation slip

line 1/0 1/15



line aux 0

line 1/0 1/15

transport input telnet

transport output telnet



So this is the way to configure a 2811 as a terminal server. The doc above I presume is meant for the 2500 series routers or similar router.

Thank you,

- sn -

ahmed.ghew Thu, 07/10/2008 - 07:21


use this configuration assuming that you using nm-16a at slot 1

ip host R1 2066


interface Loopback0

ip address


line 1/0 1/15

transport input all

sanjaynadarajah Mon, 07/14/2008 - 16:56

Well the terminal server that I had trouble configuring works now. It was due to me not adding the Group Async interface to configure the tty lines.

The doc that you presented does not address how to configure the tty lines using Group Async interface which must be done.

Thank you,


- sn -

thieu1971 Fri, 10/24/2008 - 06:26

Hi Sanjav,

I have the same issue as yours. Can you post the config where you said "It was due to me not adding the Group Async interface to configure the tty lines" Thank you


InternetB Mon, 10/27/2008 - 20:44

Here are the configs with respect to group async ....

int group async 0

no ip add

encap slip

group-range 1/0 1/15

The range of 1/0 1/15 is the configured vty lines that you should have done on :-


line vty 0 15

password xxxxx

logging synchronous


You can check the vty range if you do a 'sh line' command and the type of line should by


Hope that helps,


- InternetB -


This Discussion