Modem connected to interface async16 in cisco 2511

[maleal]

Hello again,

Today I have a more complex question (at least for me...)

I have 2 cisco access server 2511 in two different locations with the same configuration ("show running-config" is identical). In the interface async 16 (line 16) I have connected a Paradyne modem. This modem is supposed to receive calls in order to enter in the network where the router is.
My problem is that in one machine everything works fine:
- modem accepted the call;
- in the dialing computer appear the login window;
- we press the enter key and appear a message asking for the password;
- we put the password choose a ppp connection and we are inside the network;

However in the other machine we have the same configuration for this line but when appear the login window after press the enter key nothing happens - doesn't ask for the password.

I activated traces ("debug modem" command) and for the good machine I get the following:
-------------------------------
cs2#
TTY16: CTS went down on IDLE line
TTY16: CTS came up on IDLE line
TTY16: DSR came up
tty16: Modem: IDLE->READY
TTY16: Autoselect started
TTY16: Autoselect starting EXEC
TTY16: EXEC creation
%LINK-3-UPDOWN: Interface Async16, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Async16, changed state to up
-------------------------------

- In the machine which doesn't work I just have:
-------------------------------
TTY16: CTS went down on IDLE line
TTY16: CTS came up on IDLE line
-------------------------------
It seems that "DSR line" doesn't come up...
We already exchanged both modems... however the problem persists....

Anybody can give me a clue to troubleshoot this problem?

The configuration we have in both machines is:
(...)
!
interface Async16
ip unnumbered Ethernet0
ip tcp header-compression passive
async dynamic routing
async mode interactive
peer default ip address xxx.xxx.xxx.xxx
!
(...)
line 16
location maintenance modem
exec-timeout 0 30
password xxxxxxx
autoselect ppp
login
modem Dialin
transport input all
autohangup
rxspeed 38400
txspeed 38400
flowcontrol hardware
(...)

Best regards,
Miguel

 

[svermill]

Well, one suggestion would be to remove hardware flow control from your router. But that may come with consequences.

Also, did you change out the cable when you changed out the router? On a standard D25 RS-232 cable, DSR is pin 6. The most likely problem is the settings in the Paradyne. I've worked with these a lot over the years, and I seem to recall that the behavior of the control leads can be set to operate in many different ways. So make sure that DSR is pinned out in the cable and that DSR is set to go high on power up.