10-24-2002 10:38 PM - edited 03-02-2019 02:22 AM
Hello all,
my problem in theory is simple but I cannot explain the reason for this failing. I am testing an aux to aux port remote connectivity using identical US Robotics 56k voice fax modems on either side. The routers being used are X2 Cisco 2501's
There are no dip switch settings on this modem. What happens is I plug a telephone in the phone jack of modem & dial the other remote modem. The remote modem receives the call but refuses to answer. I also created a chat script obtained from www.cisco.com that first factory defaults the modem & then adds the req'ed strings.
I am at my wits ends (been trying to resolve this from Tuesday) & would appreciate any assistance, configs etc ...
Regards
Lincoln
10-25-2002 12:29 AM
Have you already checked that the modems are anwering?
It sounds to me like you have this setup in a lab environment.
It may be the case that your modems are not detecting the ring signal from the telephone exchange system. Sounds unbelievable? I have seen this happen more often than not when connecting to a non-public phone system.
Possible reasons for this are: Frequency mismatch of the ring signal, modem expects 50Hz, gets 60Hz.
Modem does not react on an external ring signal. This is often a dual ring (on for 0,4s, off 0,2s, on 0,4s) with the same duration as an internal ring-signal (on for 1,0s)
Voltage issues: Incoming ring voltage is too low. On a PABX these voltages are often lower than those from a public phone line.
To check this, watch the RI (Ring Indicator) signal toggle when a call arrives or check the Rx input for the character string: RING. Which one applies for you depends on your configuration.
Goodluck!
10-25-2002 01:40 AM
Hi, one line is public & the other is an analogue extension. Originally it was the public line calling the analogue. I've reversed the lines & re-tested as you suggested but no luck - the modem still does not answer ...
Regards
Lincoln
10-25-2002 03:42 AM
Ok then I would suggest that you confirm that the modem is giving the proper signalling upon an incoming call.
This can be achieved by observing RI (pin 22) or the modem transmitting the RING singnal to the router.
Only after you have confirmed that your modems are working as they should, and excluded cabling issues, you can dive into the configs etc.
10-25-2002 05:42 AM
At the risk of belaboring the obvious, you have verified that the modem being called is configured to auto answer? In the modem, "S" register zero configures how many rings to wait before answering the phone, a value of zero disables auto answer. Keep in mind that it is not enough just to see an "S0=2" in the setup string. Depending upon the modem, settings in the same command line as a command not recognized by the modem may be ignored, as may any commands sent immediately after a reset.
Good luck and have fun!
Vincent C Jones
10-25-2002 06:01 AM
Ok, being a test environment, I've done a 'debug all' & noticed that the router is doing a discovery for the modem although a modem cap entry has been
created.
I've tested both modems & lines & can confirm that they can both dial-out &
receive a call (tested using our Shiva dial-back server). When I call the remote
modem the 'AA' & 'SD' lights of the remote modem flicker. How else can I
confirm that both modems are sending/receiving the proper signalling. I have
ruled out the cables & modems with my test & am leaning towards the config.
A note about the routers & config - both routers are cisco 2501's & are running
ios 11.1
Regards
Lincoln
10-25-2002 06:18 AM
Lincoln,
Do you have the aux 0 line of the receiving router set for "autoselect ppp"?
Mark
10-27-2002 10:49 PM
Hi,
yes - the 'autoselect ppp' parameter has been configured on the AUX 0 line.
There is a senior networking tech that is very comfortable with modems. He
is back in the office on Monday. I will ask him on Monday/Tuesday & will let
you know how this problem was resolved. Thanks to all of you for taking the
time to help ...
Regards
Lincoln
11-14-2002 11:35 PM
Hi,
thanks to all of you for the assistance. I managed to find the problem & got this working (script reset parameter on the line aux 0). Attached are the configs of both routers. Better still is when I swopped the calling router with a GPRS unit it worked without any config changes.
The only odd aspect is that my chat-script is not being used but the routers default (does not make sense as this only worked when I changed script reset parameter). I am also using different routers (2610 for calling & 3640 for receiving).
Calling Router
sh run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname CPX
!
aaa new-model
aaa authentication login default local
aaa authentication login NO_AUTHEN none
aaa authentication ppp default local
!
username ICC password 0 a
username CPX password 0 a
!
ip subnet-zero
!
chat-script Dialout ABORT ERROR ABORT BUSY " " "AT" OK "ATDP \P" TIMEOUT 45 CONNECT \C
modemcap entry USR:MSC=&FS0=1&C1&D0&H1&R2&B1&M4&K1&M0
modemcap entry USSR:MSC=AT&FS0=1&C1&D2&H1&R2&N14&B1&W
!
process-max-time 200
!
interface Loopback0
ip address 172.16.1.1 255.255.255.0
no ip directed-broadcast
!
interface Ethernet0/0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial1/0
no ip address
no ip directed-broadcast
no ip mroute-cache
shutdown
no fair-queue
no ignore-hw local-loopback
!
interface Async65
ip unnumbered Loopback0
no ip directed-broadcast
encapsulation ppp
dialer in-band
dialer idle-timeout 214000
dialer watch-disable 60
dialer map ip 0.0.0.0 name ICC broadcast 0315606314
dialer map ip 172.16.1.2 name ICC broadcast 0315606314
dialer watch-group 8
dialer-group 1
async default routing
async mode dedicated
no fair-queue
ppp authentication chap
!
router eigrp 1
network 172.16.0.0
no auto-summary
!
ip classless
no ip http server
!
dialer watch-list 8 ip 192.1.1.0 255.255.255.0
dialer-list 1 protocol ip permit
!
line con 0
transport input none
line aux 0
exec-timeout 0 0
autoselect ppp
script reset Dialout
modem InOut
modem autoconfigure type USSR
transport input all
stopbits 1
flowcontrol hardware
line vty 0 4
!
!
end
CPX#
Called Router
sh run
Building configuration...
Current configuration : 2186 bytes
!
version 12.1
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname ICC
!
logging rate-limit console 10 except errors
aaa new-model
aaa authentication login default local
aaa authentication login NO_AUTHEN none
aaa authentication ppp default local
!
username ICC password 0 a
username CPX password 0 a
memory-size iomem 15
ip subnet-zero
!
no ip finger
!
ip audit notify log
ip audit po max-events 100
modemcap entry USR:MSC=&FS0=1&C1&D0&H1&R2&B1&M4&K1&M0
!
interface Loopback0
ip address 172.16.1.2 255.255.255.0
!
interface BRI0/0
no ip address
shutdown
!
interface Ethernet0/0
no ip address
shutdown
half-duplex
!
interface Serial1/0
no ip address
shutdown
!
interface Async129
ip unnumbered Loopback0
encapsulation ppp
dialer in-band
dialer idle-timeout 214000
dialer map ip 0.0.0.0 name CPX broadcast
dialer map ip 172.16.1.1 name CPX broadcast
dialer-group 1
async default routing
async mode dedicated
no peer default ip address
ppp authentication chap
!
router eigrp 1
network 172.16.0.0
no auto-summary
no eigrp log-neighbor-changes
!
ip classless
no ip http server
!
dialer-list 1 protocol ip permit
!
line con 0
transport input none
line aux 0
autoselect ppp
modem InOut
modem autoconfigure type USR
transport input all
stopbits 1
speed 115200
flowcontrol hardware
line vty 0 4
!
end
ICC#
Regards
Lincoln
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