Router1_aux--modem----pstn----modem--aux_Router2

[rcasta]

Hello,

Surely this might sound an easy one for some of you. Listen, I needed to set up 2 cisco 1751's and establish a ppp session by using a US Robotics modem on each router in its auxiliary port.

Let me bring out that my intention is not using this conection as a backup but rather as it's primary link (the application that runs on this line only needs up to 19kbps). However, after the modems get the session up, no traffic seems to get through and the modems end the session. (I don't even see the ppp session start) I reckon something's missing. Below is the configuration of both routers (the essencial parts at least). Thank you so much !!!

ROUTER1 calls ROUTER2. My objective is to reach network 10.10.10.0/24 that is based on Router 2.

ROUTER1 config

hostname Router1
chat-script Dialout ABORT ERROR ABORT BUSY "" "AT" OK "ATDT \T" TIMEOUT 45 CONNECT \C
chat-script USR "" "AT&FS0=1&A3&B1&G0&H1&I0&K1&M4&N0&P0&R2&U0&Y1" OK
!
interface Fastethernet0/0
ip address 172.24.1.254 255.255.255.0

interface Async5
no ip address
encapsulation ppp
dialer in-band
dialer pool-member 10
async default routing
no peer default ip address
no keepalive

interface Dialer1
ip address negotiated
encapsulation ppp
dialer pool 10
dialer idle-timeout 600
dialer string #####
dialer load-threshold 1 either
dialer group 1
!
ip route 0.0.0.0 0.0.0.0 172.24.1.1
ip route 10.10.10.0 255.255.255.0 Dialer 1
!
dialer-list 1 protocol ip permit
!
line aux 0
script connection USR
script dialer Dialout
modem Inout
transport preferred none
transport input all
transport output pad udptn telnet rlogin
speed 115200
flowcontrol hardware
!
end

ROUTER 2 (receives call from R1)

hostname Router1
chat-script Dialout ABORT ERROR ABORT BUSY "" "AT" OK "ATDT \T" TIMEOUT 45 CONNECT \C
chat-script USR "" "AT&FS0=1&A3&B1&G0&H1&I0&K1&M4&N0&P0&R2&U0&Y1" OK
!
interface Fastethernet0/0
description TARGET-LAN
ip address 10.10.10.1 255.255.255.0

interface Async5
no ip address
encapsulation ppp
dialer in-band
dialer pool-member 10
async default routing
no peer default ip address
no keepalive

interface Dialer1
ip address negotiated
encapsulation ppp
dialer pool 10
dialer idle-timeout 600
dialer load-threshold 1 either
dialer group 1
!
ip route 0.0.0.0 0.0.0.0 Dialer 1
!
dialer-list 1 protocol ip permit
!
line aux 0
script connection USR
modem Inout
transport preferred none
transport input all
transport output pad udptn telnet rlogin
speed 115200
flowcontrol hardware
!
end


I will appreciate your help !!!!

Thank you,

 

[fmonteiro]

I am missing the IP address for the assync interface. Did you configure it?
Did you try to ping the opposite router?

I would like you to post the outputs for the "sh line" and "sh line aux 0" commands. Most routers assigns interface async1 to the aux0 port but you are using the interface async5 (it may be right, but I would like to check it).

Please, check this configuration example:

http://www.cisco.com/warp/public/793/access_dial/auxback.html

It if still did not work post some of the debugs suggested in this example.

 

[rcasta]

Here is the show line: (my comments below)

#show line
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
0 CTY - - - - - 0 0 0/0 -
5 AUX 9600/9600 - - - - -

#show line aux 0
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
5 AUX 9600/9600 - - - - - 0 0 0/0 -

Line 5, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits
Status: Ready, Modem Signals Polled
Capabilities: none
Modem state: Ready
Modem hardware state: noCTS noDSR DTR RTS
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.

Therefore, I think, the Async no. 5 interface is the way to go. As far as the Ip address, I thought that by using "ip address negotiated" would work. Do you think this is the problem? On the other hand, what about the Aux configuration, do I need the "autoselect ppp" command?

I'd really appreciate your help!!!

 

[rcasta]

By the way, please note that these routers are not back to back through the aux port but rather are separated by analog modems (US Robotics).

As soon as I ping or send traffic from Router1 to Router2, Router1 dials the Router 2's modem (using analog phone lines), the latter answers and everything ends here.

Thank you,

 

[fmonteiro]

I have never used the "ip address negotiated" command. Take a look at this definition from Cisco:
Usage Guidelines
This command first appeared in Cisco IOS Release 11.3.
Use the ip address negotiated interface command to enable a Cisco router to automatically negotiate its own registered WAN interface Internet Protocol (IP) address from a central server (via PPP/IPCP) and to enable all remote hosts to access the global Internet using this single registered IP address.

I would suggest configuring a fixed IP, at least for while.

Please set the "debug dialer events" and "debug dialer packets" on Router1.

Make a call from router1.

While the call is in progress do a "show line aux 0".

Please post the output for the debug commands and the sh line.

 

[rcasta]

I'll post them tomorrow this output tomorrow. As far as the ppp commands is concerned, I've read somewhere at Cisco's site that the called router needs the PPP AUTOSELECT. Furthermore, I still have my doubts on whether using the async interactive/dedicated modes, I mean, do I need these commands as well?

I'm asking since in some examples these commands are omitted and sometimes they aren't.

Thank you ! I'll keep you posted.

best regards,

 

[fmonteiro]

I do not believe this is our problem but you may add a async mode interactive (async interface) and autoselect ppp (line aux) in both routers.
The point is that specifying interactive you need to specify the autoselect. Specifying async mode dedicated you do not need the autoselect.

I hope the debugs you give us a better understanding or your problem.

 

[rcasta]

Today, I'll post debug results at the earliest.

In the meanwhile, I can't seem to find a full explanation of what the modes dedicated and interactive are for. I vaguely understood a bit but not quite the whole picture.

Thank you,

 

[fmonteiro]

When using async mode interactive you may define a autolect
<protocol>, where <protocol> could be arap / ppp / slip / during-login. If you choose during-login, after the login you select the protocol you are going to use.

When using async mode dedicated you should define an encapsulation <protocol>, where protocol could be slip and ppp. This mean that the user can not change the protocol dynamically.

 

[rcasta]

Hello,

Sorry for not posting promptly the debug results, nevertheless let me tell you that it finally worked. Furthermore, I left several lines of configuration out and it ended like this:

interface Serial0/0
no ip address
shutdown
!
interface Async5
no ip address
encapsulation ppp
dialer in-band
dialer pool-member 10
async default routing
async mode dedicated
no peer default ip address

interface Dialer1
ip address 192.168.1.1 255.255.255.252
encapsulation ppp
dialer pool 10
dialer string ####
dialer-group 1
!
ip classless
ip route 10.10.10.0 255.255.255.0 Dialer1
!
dialer-list 1 protocol ip permit
!
line con 0
line aux 0
script dialer Dialout
modem InOut
modem autoconfigure type usr_sportster
transport input all
speed 115200
flowcontrol hardware

Unfortunately I didn't have time to remove the &quot;async mode dedicated&quot; command and see if it still worked.

Anyway, perhaps having before the &quot;ip address negotiated&quot; caused the trouble for no router server (dhcp perhaps?) would give the other one an IP address.

Thank you for assisting me on this, I do appreciate it ! I will try putting off the &quot;async mode dedicated&quot; and see what happens.

Best regards,

 

[fmonteiro]

I am happy it has finally worked. It was a pleasure assisting you.

Best regards,

 

[rcasta]

By the way, I further noticed that you must disable Fast Switching from the Dialer interface. Before doing so, the R1 was dropping packets when entering into the aux interface. I guess it messes up in the cache table or something. Any thoughts on this?

Thank you,