Cisco 891 AUX-CON port - having issues

[Adam Ayoub]

Good morning,

I am having trouble connecting to a Cisco 891 from a Cisco 871 with a flat CON-AUX cable. Both routers use the same port for AUX-CON and I have a flat cable plugged into both (I've tested the cable on a 4331 and it works perfectly).

When I do a telnet C871 2001, I cannot reach the 891 router. It just hangs after I enter the password. I have used this many many times on bigger routers that have two different ports for the console and auxiliary but for the 800 series, I am having trouble. Am I missing a configuration somewhere or are the routers not distinguishing AUX from CON?

I've configured both line con 0 and line aux 0 on both routers I want to access to no avail.

Any help would be much appreciated.

Thank you.

[Diana Karolina Rojas]

Did you aplied this configuration on your Auxiliary port?

line aux 0

transport input telnet

no exec

Regards,

[Adam Ayoub]

Yes, in fact, this is what I have:

line aux 0
 exec-timeout 30 0
 no exec
 transport input telnet ssh
 transport output none

I even tried changing the output to telnet ssh as well but it didn't work either. Still struggling with this.

[Diana Karolina Rojas]

Ok, When you do a "sh line" what number is your Auxiliary line? Are you sure that it is 1? Have you tried to set a password and login on the aux line?

Regards,

[Adam Ayoub]

Yes it's a 1. I tried 2001, 2101, 2201 just in case and nothing. I also tried putting login and password.

show line
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
*     0 CTY              -    -      -    -    -      0       1     0/0       -
      1 AUX      0/0     -    -      -    -    -      0       0     0/0       -
      3 TTY              - inout     -    -    -      0       0     0/0       -
*    10 VTY              -    -      -    -    -      9       0     0/0       -
     11 VTY              -    -      -    -    -      0       0     0/0       -
     12 VTY              -    -      -    -    -      0       0     0/0       -
     13 VTY              -    -      -    -    -      0       0     0/0       -
     14 VTY              -    -      -    -    -      0       0     0/0       -

Also, after I attempt to login, and after it starts to hang, I just do a sh line on the router I'm trying to connect from and there's a star next to the AUX line:

sh line
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
*     0 CTY              -    -      -    -    -      0       7     0/0       -
*     1 AUX      0/0     -    -      -    -    -      1       0     0/0       -

So it is reaching it but why is it not doing anything after I get into the router?

[Diana Karolina Rojas]

Ok, Another thing you can do it's to use this commands in your configuration on the AUX line:

 #modem InOut

 #flowcontrol hardware

Try this and tell me the result.

---Do not forget to rate useful answers---

Regards,

[Adam Ayoub]

Still hangs :(

line aux 0
 exec-timeout 30 0
 password cisco
 modem InOut
 no exec
 transport input telnet ssh
 transport output telnet ssh
 flowcontrol hardware

Maybe I should do something similar on the console line in the router I'm trying to reach?

[Diana Karolina Rojas]

I thinks is strange that your AUX line do not have any  values in the Tx and Rx baud rates,

1 AUX      0/0     -    -      -    -    -      0       0     0/0       -

Can you try to use different speeds in both devices?

(config)#line aux 0

(config-line)#speed 9600

[Adam Ayoub]

show line
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
      0 CTY              -    -      -    -    -      0      17     0/0       -
*     1 AUX   9600/9600  - inout     -    -    -      9       0     0/0       -
      3 TTY              - inout     -    -    -      0       0     0/0       -

Still unable to connect via telnet 2001. So odd. I tried removing modem config on first router and added modem enable on the console line on the second router. Didn't work either.

Google doesn't have any answers either lol.

EDIT: Tried 4800 also. Didn't work.

I am so sure it's a small configuration to make the port distinguish what is AUX and what is CON since it's using the same port. Unless I'm mistaken and it shouldn't matter.

[Diana Karolina Rojas]

Issue the show line aux 0 command and show me the output and the configuration of both sites. 

[Adam Ayoub]

Sure. Here's the "FROM" router:

show line aux 0
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
      1 AUX   4800/4800  - inout     -    -    -     11       0     0/0       -

Line 1, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 4800/4800, no parity, ?? stopbits, 0 databits
Status: CTS Raised
Capabilities: EXEC Suppressed, Hardware Flowcontrol In,
  Hardware Flowcontrol Out, Modem Callout, Modem RI is CD
Modem state: Idle
Special Chars: Escape  Hold  Stop  Start  Disconnect  Activation
                ^^x    none   -     -       none
Timeouts:      Idle EXEC    Idle Session   Modem Answer  Session   Dispatch
               00:30:00        never                        none     not set
                            Idle Session Disconnect Warning
                              never
                            Login-sequence User Response
                             00:00:30
                            Autoselect Initial Wait
                              not set
Modem type is unknown.
Session limit is not set.
Time since activation: never
Editing is enabled.
History is enabled, history size is 20.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed input transports are telnet ssh.
Allowed output transports are telnet ssh.
Preferred transport is telnet.
Shell: enabled
Shell trace: off
No output characters are padded
No special data dispatching characters

"TO" Router (Both con0 and aux0):

show line con 0
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
      0 CTY              -    -      -    -    -      0      18     0/0       -

Line 0, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits
Status: Ready
Capabilities: none
Modem state: Ready
Modem hardware state: CTS* noDSR  DTR RTS
Special Chars: Escape  Hold  Stop  Start  Disconnect  Activation
                ^^x    none   -     -       none
Timeouts:      Idle EXEC    Idle Session   Modem Answer  Session   Dispatch
               00:30:00        never                        none     not set
                            Idle Session Disconnect Warning
                              never
                            Login-sequence User Response
                             00:00:30
                            Autoselect Initial Wait
                              not set
Modem type is unknown.
Session limit is not set.
Time since activation: never
Editing is enabled.
History is enabled, history size is 20.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed input transports are none.
Allowed output transports are pad telnet rlogin lapb-ta ssh.
Preferred transport is telnet.
Shell: enabled
Shell trace: off
No output characters are padded
No special data dispatching characters

show line aux 0
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int
      1 AUX   4800/4800  -    -      -    -    -      0       7     0/0       -

Line 1, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 4800/4800, no parity, 2 stopbits, 8 databits
Status: Ready, CTS Raised
Capabilities: EXEC Suppressed
Modem state: Ready
Special Chars: Escape  Hold  Stop  Start  Disconnect  Activation
                ^^x    none   -     -       none
Timeouts:      Idle EXEC    Idle Session   Modem Answer  Session   Dispatch
               00:10:00        never                        none     not set
                            Idle Session Disconnect Warning
                              never
                            Login-sequence User Response
                             00:00:30
                            Autoselect Initial Wait
                              not set
Modem type is unknown.
Session limit is not set.
Time since activation: 00:23:24
Editing is enabled.
History is enabled, history size is 20.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed input transports are none.
Allowed output transports are none.
Preferred transport is telnet.
Shell: enabled
Shell trace: off
No output characters are padded
No special data dispatching characters

EDIT:

I tried connecting to the 891 from a 4331 just to test if it's the console or the auxiliary that isn't working. Doing a telnet 2001 from the 4331 to the 891 works. When I did the reverse, it was doing the same behaviour as it was doing with the two 891s. So we know the problem is with the AUX port. Probably some missing config.

[Adam Ayoub · Accepted solution]

I've found the solution.

On the FROM 891, we need to put "modem enable" on line con 0. On the TO 891, we need to put "no modem enable" on line con 0.

Thanks for the help, really appreciate it.

[Diana Karolina Rojas]

Hello Adam!

I'm glad you found the solution to the problem, thanks for sharing it. And you do not have to thank me on the contrary, now I can learn from your experience.

Have a happy day!

Regards,

[damienpicard]

Thank you ! I had the exact same issue and this solution is working for me.