How to connect C8200 Console port via async port (NIM 16) of C8200.

[PMelinn]

Hi I have been trying connecting a router B from a router A via Async to console port. It's not working. Have configured async port and line port as well. But whenever I telnet the line, it takes me to the Cisco 8200 A (terminal server) itself. It's a 8 port Aync cable. 

[liviu.gheorghe]

Hello @PMelinn ,

Assuming you want to connect the first async port from router A to the console port of router B. Also assuming you are using the correct cabling - an octal breakout cable with RJ45 connectors.

Log in to router A and issue the show line command to see the id of your first async line. You will have something like this:

TS_EVO>sho line
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
0 CTY - - - - - 1 0 0/0 -
33 TTY 9600/9600 - - - - - 1 174670 0/0 -
34 TTY 9600/9600 - - - - - 4 19 2/0 -
35 TTY 9600/9600 - - - - - 10 3345 0/0 -
36 TTY 9600/9600 - - - - - 6 384 0/0 -
37 TTY 9600/9600 - - - - - 0 22 0/0 -
38 TTY 9600/9600 - - - - - 0 32837 1/0 -
39 TTY 9600/9600 - - - - - 0 21247 0/0 -
40 TTY 9600/9600 - - - - - 0 42802 0/0 -
41 TTY 9600/9600 - - - - - 0 0 0/0 -
42 TTY 9600/9600 - - - - - 0 0 0/0 -
43 TTY 9600/9600 - - - - - 0 0 0/0 -
44 TTY 9600/9600 - - - - - 0 0 0/0 -
45 TTY 9600/9600 - - - - - 0 0 0/0 -
46 TTY 9600/9600 - - - - - 0 0 0/0 -
47 TTY 9600/9600 - - - - - 0 0 0/0 -
48 TTY 9600/9600 - - - - - 0 0 0/0 -
65 AUX 9600/9600 - - - - - 0 0 0/0 -
* 66 VTY - - - - - 645 0 0/0 -
67 VTY - - - - - 14 0 0/0 -
68 VTY - - - - - 1 0 0/0 -
69 VTY - - - - - 0 0 0/0 -
70 VTY - - - - - 0 0 0/0 -
71 VTY - - - - - 0 0 0/0 -
72 VTY - - - - - 0 0 0/0 -
73 VTY - - - - - 0 0 0/0 -
74 VTY - - - - - 0 0 0/0 -
75 VTY - - - - - 0 0 0/0 -
76 VTY - - - - - 0 0 0/0 -
77 VTY - - - - - 0 0 0/0 -
78 VTY - - - - - 0 0 0/0 -
79 VTY - - - - - 0 0 0/0 -
80 VTY - - - - - 0 0 0/0 -
81 VTY - - - - - 0 0 0/0 -

Line(s) not in async mode -or- with no hardware support:
1-32, 49-64

In my case, the first async line is 33. You should configure your async lines with the same parameters as the console line:

line 33 48
login authentication no-auth
transport input all

speed 9600

databits 8

parity none

stopbits 1

Now that you have configured your async lines, in order to access the first line issue the following command in my case

TS_EVO>telnet 172.25.255.10 2033
Trying 172.25.255.10, 2033 ... Open

Unauthorized access to this device is prohibited!

Username:

The IP address used for telnet is any IP address configured on a router interface that is up, the port following the IP address is made up by adding 2000 to the id of the async line you want to use - in my case the first line is 33 and the port is 2033.

What you see after the "Trying 172.25.255.10, 2033 ... Open" message is from the other devices console.

Hope this helps.

[Elliot Dierksen]

I would add "no exec" to lines that you are using for outbound connections to the console of other devices. If exec is enabled, it does two undesirable things. The chatter between the two devices can eat up a bunch of CPU. Also, the port will be unavailable for outbound connections because the router thinks something is trying to log in inbound on that line.

[liviu.gheorghe]

Yes, usefull sugestion. 

[vishalbhandari]

@PMelinn 

It sounds like the reverse telnet configuration isn't fully set up. Ensure the async interface on Router A (terminal server) is correctly associated with the corresponding line using the ip host command. For example, use ip host RouterB 2002 <RouterA_IP> where 2002 corresponds to the async line. Also, confirm the line configuration (line 2) has transport input telnet and matches the async interface. If the cable and hardware are fine, this setup should direct your telnet to Router B's console via Router A.