DDR ISDN issue

[networker]

Hi all,

I plan to have 2 simultaneous ISDN connections on a unique BRI interface in a Cisco 1721 router.
I have tried with the configuration below but the DDR
doesn't work: the ISDN call does not start when I ping to the other side (despite interesting traffic is defined through the dialer list).
However, if I make a call through the "isdn call interface bri" command, the call is correctly established. Remote names, dialer strings and IP addresses are already checked.

Thank you in advance!


interface BRI0
no ip address
encapsulation ppp
dialer pool-member 1
dialer pool-member 2
isdn switch-type basic-net3
no cdp enable

interface Dialer1
ip address A.B.C.E 255.255.255.252
encapsulation ppp
no ip split-horizon
dialer pool 1
dialer remote-name aaaaaa
dialer string YYYYYYYYYY
dialer hold-queue 10
dialer snapshot
dialer-group 2
snapshot client 15 360 suppress-statechange-update dialer
no cdp enable
ppp authentication chap

interface Dialer2
ip address A.B.C.D 255.255.255.252
encapsulation ppp
no ip split-horizon
dialer pool 2
dialer remote-name bbbbbb
dialer string XXXXXXXX
dialer hold-queue 10
dialer snapshot
dialer-group 2
snapshot client 15 360 suppress-statechange-update dialer
no cdp enable
ppp authentication chap

dialer-list 2 protocol ip permit

 

[ccie9545]

what happens when you use debug dialer and attempt to ping Erik Rudnick, CCIE No. 9545
mailto:erik@kuriosity.com

 

[networker]

Nothing happens when I use "debug dialer" and "debug isdn events".
The router doesn't start the call automaticlly. I have tried to make the call manually, and then ping the other side, but it doesn't work neither.
Any other suggestions?

Thanks!

 

[ccie9545]

if you debug ip packet are they trying to exit out of the dialer interface?

you can try configuring the physical interface with necessary parameters to dial one of the ISDN numbers. This will at least narrow down some of the problems....

one other thing, you will probably have to put ppp authentication chap on the physical interface as well as the dialer interfaces.

what is the output of the show isdn status? Erik Rudnick, CCIE No. 9545
mailto:erik@kuriosity.com

 

[networker]

Here is the output of the "show isdn status":


Global ISDN Switchtype = basic-net3
ISDN BRI0 interface
dsl 0, interface ISDN Switchtype = basic-net3
Layer 1 Status:
ACTIVE
Layer 2 Status:
TEI = 65, Ces = 1, SAPI = 0, State = TEI_ASSIGNED
Layer 3 Status:
0 Active Layer 3 Call(s)
Active dsl 0 CCBs = 0
The Free Channel Mask: 0x80000003
Number of L2 Discards = 0, L2 Session ID = 13
Total Allocated ISDN CCBs = 0


Unfortunately I cannot make a "debug ip packet" due to the amount of traffic that the router is processing through other interfaces.
I have tried the following configuration (1 connection only) and it works .


isdn switch-type basic-net3

interface BRI0
description connected to nekcap,enacap
no ip address
encapsulation ppp
dialer rotary-group 1
dialer-group 1
isdn switch-type basic-net3
no cdp enable

interface Dialer1
ip address A.B.C.E 255.255.255.252
encapsulation ppp
no ip split-horizon
dialer in-band
dialer map snapshot 1 name aaaaaa broadcast YYYYYYYYY
dialer map ip A.B.C.F name aaaaaa broadcast YYYYYYYYY
dialer hold-queue 10
dialer-group 1
snapshot server 15 dialer
no cdp enable
ppp authentication chap

dialer-list 1 protocol ip permit



Thanks again.

 

[ccie9545]

The first thing that I see as being abnormal is that the layer 2 status is TEI_Assigned. The layer two status should be multiple_frame_established. There are a number of reasons that this could be the case. For example, this could mean that the router has lost connectivity to the telco switch. In Europe some telcos disconnect if there is not any activity. try debugging isdn q921, this will give you information on layer two establishment. If you would like here is a couple of good articles regarding the subject.

http://www.cisco.com/warp/public/129/bri-layer2.html

http://www.cisco.com/warp/public/129/bri_sh_isdn_stat.html

Erik Rudnick, CCIE No. 9545
mailto:erik@kuriosity.com

 

[networker]

When I debug ISDN Q.921, I see periodic exchanges of RRf sapi = 0 and RRp sapi = 0, so the link between the router and the switch is definetively up.
Actually, it works with the second configuration I posted before. The connection is established when traffic is to be passed.
I guess it is a DDR problem, but I don't know where it is located...
Could it be a IOS bug?

Thanks!

 

[ccie9545]

try using a dialer string in the second configuration. The one that was working with the dialer maps. Substitute dialer string command for dialer map command and see if you still get connectivity. Erik Rudnick, CCIE No. 9545
mailto:erik@kuriosity.com

 

[networker]

Hi again,

I can't substitute "dialer string" command by "the dialer map ip" with the dialer pool configuration. I should use "dialer rotary-group" to make it work, but with this command I can only make one simultaneous connection, like the second case I posted.

 

[ccie9545]

hopefully you got everything working alright....been on a little vacation....if it is not working do you think you could email me the entire configs for all routers, adn i can set it up in our lab... Erik Rudnick, CCIE No. 9545
mailto:erik@kuriosity.com

 

[jeroenw1]

Hi all,

I'm not a specialist on this subject but I happen to have a 1720 on which I managed to configure DDR:
in the two (in my case 3; 1 dial-in) dialers I use the dialer string command. After that I defined the routes to point to the dialers: ip route 192.168.116.0 255.255.255.0 dialer1 AND ip route 192.168.117.0 255.255.255.0 dialer 2