Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

IOS 12.4 undocumented commands RFC2217 AS5350 Cisco2820

I have Cisco 2820s and AS5350s with IOS 12.4

The following commands are undocumented:

ip telnet comport enable

ip telnet comport receive

ip telnet comport flow

ip telnet comport disconnect

Anyone able to clarify exactly what these commands do?




Re: IOS 12.4 undocumented commands RFC2217 AS5350 Cisco2820

RFC 2217 Telnet Com Port extensions are used to communicate modem hardware signal status from a modem on a network access server (NAS) to a TCP/IP client. An example would be a client PC using a package such as DialOut/EZ ( to provide an emulated COM port via a TCP connection to a Cisco AS5000 NAS with integrated modems.

When Com Port extensions are enabled on the NAS, the binary Telnet option (RFC 856) should be used. The Telnet client must connect to TCP port 6000 + for individual lines, or 7000 + for rotaries on the Cisco NAS.

New Member

Re: IOS 12.4 undocumented commands RFC2217 AS5350 Cisco2820

Nice try

I found that documentation too.

Unfortunately it only describes ip telnet comport enable.

That command seems to have little effect, because all the RFC2217 services work even if the command is not in effect. It is possible to communicate with a NAS on TCP port 2000+, 4000+, 6000+ and 7000+ for rotaries.

It's the un-documented commands that I'm interested in though.

CreatePlease login to create content