Re: question about PPP authentication

From: Ellie Chou (ellie_chou@hotmail.com)
Date: Thu Dec 11 2003 - 00:37:30 GMT-3


I have PPP configured on both sides but PPP authentication chap
configured on one side only. I guess my question is pretty fundamental (
just started playing with ISDN): why are there two unidirectoinal links?
Let's say A calls B, and the traffic that triggers the call is ping. So
my guess in order to send back ping reply back to A, B has to initiate
another call to A, therefore there are two connections. But why can't B
recognize the ping reply desitnation is A and there is already an active
call? I found that only when both A and B have PPP encapsulation and PPP
authentication chap, only one channel is used. In any other condition two
channels are used.

Here is the configuration:

RouterA:

interface BRI0/0
 ip address 144.4.13.1 255.255.255.252
 encapsulation ppp
 dialer map ip 144.4.13.2 name L1R3 broadcast 5551616
 dialer-group 1
 isdn switch-type basic-ni
 isdn spid1 31055514140101 5551414
 isdn spid2 31055515150101 5551515
 ppp authentication chap

RouterB:

interface BRI0/0
 ip address 144.4.13.2 255.255.255.252
 encapsulation ppp
 dialer map ip 144.4.13.1 name L1R1 broadcast 5551515
 dialer-group 1
 isdn switch-type basic-ni
 isdn spid1 31055516160101 5551616
 isdn spid2 31055517170101 5551717

thanks,

Ellie

>From: "Adel Abushaev" >Reply-To: "Adel Abushaev" >To: >Subject: Re:
question about PPP authentication >Date: Wed, 10 Dec 2003 15:06:05 -0500
> >It looks like you have 2 unidirectional links, one per B-channel. >Do
you have PPP configured on both sides or only on one? >Or is it
authentication you configured on one side only? Or just show your >BRI
configuration to the list. > >Adel Abouchaev >CCIE# 12037, MCSE
>http://www.netmasterclass.net > >----- Original Message ----- >From:
>To: >Sent: Tuesday, December 09, 2003 10:58 PM >Subject: question about
PPP authentication > > > > Hi, > > > > I am running PPP over ISDN. > >
Can anyone tell me if I have "ppp authentication chap" configured on one
>side but nothing configured on the other side. What would the
negotiation >look like? I tried it on my setup, let's say routerA and
router B. When I >ping B from A(classified as interesting traffic), two
ISDN connection are >established, one shows A as caller and one show B as
caller. Can someone >help me on this? thanks a lot!!!! :-) > > > > Ellie
> > > >



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