Using NM-16A/S or NM-32A/S is easy peasy, because they are dedicated terminal server modules and you have octal cables. But NM-8A/S is a bit more complex because you need more cables, adapters, and special commands to get this working. Now, I don’t recommend the NM-8A/S modules but sometimes you can get them really cheap compared to the other ones, so here’s how to set it up as a terminal server:
- put the module into a 2621xm router (or any of the routers listed on nm-8A/S Cisco page)
- take a Cisco CAB-232MT cable, connect it to one of the ports on the module
- take the male end of the CAB-232MT cable and connect it to DB-25female>DB9male adapter.
- connect the adapter to a standard cisco blue console cable
- plug the rj45 into some other router’s console port
Now power up the 2621xm, go to the serial interface (remember that they’re numbered from the right):
conf t int s1/0 physical-layer async
This causes the serial to go into async mode.
Now issue the command:
This command shows you which line you need to use (in my case it was line 33, because the it’s S1/0 module. If it was S0/0 module, it would be line 1.)
Then, make a loopback0 interface and add an ip address to it:
int loop0 ip addr 10.0.0.1 255.255.255.0
Then, go to the line interface and modify the transport parameters:
conf t line 33 transport input telnet transport output telnet
Finally, create a host/port mapping:
ip host R1 2033 10.0.0.1
This maps the address/port to the name of the router that you want to manage.
Now you can manage other routers by telnetting to this router’s loopback interface:
telnet 10.0.0.1 2033
This moves you to the R1 console port.
Alternatively, just type R1 and press Enter.
You can use Shift+Ctrl+6 and then X to leave the managed router and go back to your terminal server.
Now add more mappings for other managed routers:
ip host R2 2034 10.0.0.1 ip host R3 2035 10.0.0.1 ip host R4 2036 10.0.0.1
and so on and so forth.