Terminal Server

Cisco Terminal Server

When you have multiple devices and you want their console access or when you have to configure devices remotely then only way to do that is to use Terminal server.

Cisco Terminal server is basically a device which use octal cable or roll over cable to connect console port of other devices. 2 type of Terminal servers are available.

  1. Which use Roll over cable (For more details of roll over cable check my post of cables)

These Devices have RJ45 ports for roll over cable, We connect one end of Rollover cable to terminal port and other to console of device you want to access.


as in above picture 16 ports on left side are Terminal port (Async. port). Color code of roll over cable is as mentioned in below picture.

127840     2. Which use Octal Cable:-

These devices use Octal cable, this cable have 1 Async port at one end and 8 Rj45 port on other end as mentioned in below picture.

cab_oct_asyncAsync port get connected to Terminal server and other end goes to Console port of devices. All the 8 cables are marked with their number which are use full to identify the line number.

Cisco provide 2500 series devices as Terminal Access Server, but you can add module for octal cable in ISR series devices also like 1841 and etc.


Terminal Server Configuration

I am using Packet tracer for this lab. I have used an external module in 1841 and will configure it as Terminal Server.

Octal labTo configure an terminal server first we need to configure IP address and telnet/ssh services so that if we want its access from outside we can take.

Once above settings are done we will start configuration of Terminal server.

Step 1:- Configure Loop back interface.

Terminal(config)#interface loopback 1
Terminal(config-if)#ip add


Step 2:- Find the line number of async port so that we can configure it as requirement.

Terminal#sh line

Octal Lab2

Check the bottom of output you can see that line which are not in async mode are 2-17 and 26-193, that means line 18-25 are async, also if you check output from line 18-25 it shows 0/1/* which is of Hardware support.

Now that we know that line number we need is 18 to 25 (cisco use 2000 onwards line for terminal server so our line will be 2018 to 2025)

Step 3:- Now Identify your device and on which cable it is physically connected i.e if your cable 1 is connected on R1 then its line will be 2018 and line of cable 8 will be 2025.

so We will configure line as

ip host R1 2018

Where R1 is friendly name of device which is connected on cable 1.
2018 is line number which we get from Step 2. is Ip address of Loopback interface which we configured on step 1.

Configure all the lines as required.

Terminal(config)#ip host R1 2018
Terminal(config)#ip host R2 2019
Terminal(config)#ip host R3 2020
Terminal(config)#ip host R4 2021


Step 4:- Configure permission on line so that we can access the devices

Terminal(config)#line tty 18 25
Terminal(config-line)#no login
Terminal(config-line)#no pass
Terminal(config-line)#transport input telnet


Step 5:- Now to access devices just enter their friendly name:-

Trying …Open
% Please answer ‘yes’ or ‘no’.
Continue with configuration dialog? [yes/no]: no
Press RETURN to get started!
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ho R1

to go back to Terminal server press “ctrl + shift + 6” release and then press “x”. You will be back to Terminal server where you can go to any other device.

Trying …Open
% Please answer ‘yes’ or ‘no’.
Continue with configuration dialog? [yes/no]:

Now to go back to R1 you have to first return to Terminal server and check for running sessions

Terminal#sh sessions


Octal lab3

To return to R1 just press 1 (Conn  number) and hit enter.


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