Cisco Aux Port New Router

[matt.harte@nats.co.uk]

Hi All, 

Within my company we tunnel Async traffic over SSH between locations for Legacy low speed applications. At the moment we have 4000 series routers with NIM-24 Async modules that connect to the host system and Cisco routers 881v and Cisco 4321 at the remote locations. The Cisco 881v has a combined CON/AUX port which you can select as either a CON or AUX by adding the "modem enable". This allows use to outlet the legacy Async traffic using the CON port to the terminal. 

We want to look at doing the same with newer routers replacing initially the 881v routers. We use the 881v routers as they have FXS ports for voice connections as well as 4 ethernet ports for IP applications. I have tried a VG400 and even though when you do a "show line" it shows a AUX port it does not physically exist or a combined CON/AUX. Also the "modem enable" command under line con 0 does not exist. 

I know I can use a 8200 with a NIM Async module but it will get really expensive as we have around 40 sites that utilise this Async application. Using the CON port as an AUX port saved us lots of money. Yep the application should be IP capable but its going to take sometime for this to be done.

I can't find any documentation to say if you can use a CON port as an AUX port on modern routers these days. 

Thanks

Matt

[pieterh]

look at this page https://www.cisco.com/c/en/us/support/docs/switches/catalyst-5000-series-switches/12016-2.html
this is a specific model, but will be valid for most console ports
the reference at the end is more detailed and could also be valuable 

Note: The connection of modems to the console port of a switch has some disadvantages. There are also security concerns of which to be aware. Some examples are:

• The console port does not support RS232 modem control (DSR/Data Carrier Detect [DCD], data terminal ready [DTR]). Therefore, when the EXEC session terminates (logout), the modem connection does not drop automatically; the user needs to manually disconnect the session.

• More seriously, if the modem connection drops, the EXEC session does not automatically reset. This failure to reset presents a security hole; a subsequent call into that modem is able to access the console without the entry of a password. You can make the hole smaller if you set a short EXEC timeout on the line. However, if security is important, use a modem that can provide a password prompt.

If you plan to connect a modem to the console port of any Catalyst switch, first refer to the Console Port Issues section of the Modem-Router Connection Guide. The document provides the risks and limitations as well as the advantages of this procedure.