From: jano@rhox.com.br
Date: Sun Nov 14 2004 - 09:32:26 GMT-3
Hi,
I would like to know how the mechanism behind the "dialer string" command
works? Here follows some background info:
I found a good mail in the archives explaining the "dialer map" command:
"Dialer maps require that the called router knows what router is calling
it. If you are not running pap/chap it relies on the Caller ID info. If
there is no dialer string in the map statement on one end, then there is
nothing to tie the incoming call to the map and you will not have
connectivity."
Example 1 - this configuration does NOT work:
---------------------------------------------
"show isdn active" on the called router (R1) confirms that it does NOT
know who called it - Remote Name is unknown. So for some reason Caller ID
info is not used by R1. So there is no info to tie the dialer map on R1 to
R2, and you have no connectivity.
R1
int BR0/0
encap ppp
dialer map ip 120.20.21.2 name R2
dialer-group 1
R2
int BR0/0
encap ppp
dialer map ip 120.20.21.1 8358661
dialer-group 1
Example 2 - but this configuration DOES work:
---------------------------------------------
In this config the CHAP authentication helps R1 to know who dialed. "show
isdn active" confirms that R1 knows that R2 dialed it, and you have
connectivity.
R1
int BR0/0
encap ppp
dialer map ip 120.20.21.2 name R2
ppp auth chap
dialer-group 1
R2
int BR0/0
encap ppp
dialer map ip 120.20.21.1 8358661
ppp auth chap
dialer-group 1
What I want to know is when you use the "dialer string" command how does
the called router know who is the calling router, without any
authentication?
Example 3 - This config DOES work:
----------------------------------
R1
int BR0/0
encap ppp
dialer string 8358662
dialer-group 1
R2
int BR0/0
encap ppp
dailer string 8358661
dialer-group 1
"show isdn active" on R1 shows the Remote Name as R2. How did R1 learn
this information? Did it use Caller ID info? But why did the Caller ID
info no work in Example 1?
Regards.
Jano
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