ISDN Dialer Map does not support Bidirectional Traffic !!!

From: Arun Arumuganainar (aarumuga@hotmail.com)
Date: Sat Aug 20 2005 - 12:57:25 GMT-3


I was working with ISDN !!! I came up on a problem !!!

My Topology looks like this .

R2--------------R5
    Bri0/0 Bri0/0

My configurations goes like this

Router 2
isdn switch-type basic-net3
int bri0/0
 ip address 150.50.9.2 255.255.255.252
 dialer map ip 150.50.9.5 name Router-5 broadcast 5552000
 dialer-group 1
dialer-list 1 protocol ip permit
===============================================
Router 5
isdn switch-type basic-net3
int bri0/0
 ip address 150.50.9.2 255.255.255.252
 dialer map ip 150.50.9.5 name Router-2 broadcast 5551000
 dialer-group 1
dialer-list 1 protocol ip permit
===============================================

After configuring like this when I send ping packets from Router 2 to Router
5 . I observe a strange behaviour !!! Forward traffic goes via one BRI
channel and Return traffic goes via another !!!

The behaviour is same when

a) I ping on either directions ( i.e R2-R5 and also From R5 to R2 ) .
b) The behaviour is observed with both HDLC and PPP encapsulaton ( IP Expert
Protor Guide Say with PPP encap. traffic per bri channel should be
bi-directional ) . But I could not notice this !!!

When I removed dialer map on one side !!! Packet from the other side reaches
it . But the return traffic is dropped due to encapsulation failure ( I
observed this with debug ip pack ) !!!

One work around for this : use dialer string instead of dialer maps !!! With
Dialer strings I am able to achive two way traffic using single BRI channel
for both HDLC and also PPP Encapsulations !!!!

I am wondering is this the right behavior ???!!!! It would be great if any
body can clarify !!!

Thanks and Regards
Arun



This archive was generated by hypermail 2.1.4 : Sun Sep 04 2005 - 17:01:19 GMT-3