ISDN connection from 2 remote offices to HQ

[chongtl]

I have 2 remote offices connect to HQ via ISDN line. They are using Cicso 1700 series. My ISDN line have 2 numbers. I dedicated each number to each remote office. In another words, each remote office dial specific number to HQ ISDN.

When I did the testing, both remote offices can connect to HQ.

My problem is every morning someone from HQ need to ping one of the router, in order to make that router connect to HQ. Everyday different office.

Can anyone tell me what is the problem ?

What is the best to connect the 2 remote office to 1 ISDN line/ router in HQ ?

Thanks

 

[routerman]

The way I would do this is to have 1 dialer interface per remote office, so your HQ router would have 2 dialers configured.

Smething like:


username office1 password SAME-AS-OFFICE-1
username office2 password SAME-AS-OFFICE-2

int bri1
encap ppp
ppp auth chap
dialer pool-member 1
no ip addr

int d1
encap ppp
dialer pool 1
ip addr n.n.n.n 255.255.255.252
dialer string 12345678
dialer remote-name office1
ppp auth chap
dialer-group 1
dialer max-call 1

int d2
encap ppp
dialer pool 1
ip addr y.y.y.y 255.255.255.252
dialer string 87654321
dialer remote-name office2
ppp auth chap
dialer-group 1
dialer max-call 1

dialer-list 1 protocol ip permit

ip route IP-REMOTE-LAN-1 MASK int d1
ip route IP-REMOTE-LAN-2 MASK int d2

Is this similar to what you have configured?? This should allow 2 connections into the central router.

One thing that may be a problem, can you check the ISDN status before you have to send the ping, look at the Layer 1, should be active, with Layer 2 TEI assigned.

Useful debug, debug dialer, debug ISDN q931

 

[chongtl]

Thanks for your reply.

Basically my configuration for HQ is the same as your sample. But I added ppp multilink for the Int Bri1, d1 & D2.
Is it causing the problem ?

For remote office, I also added the PPP multilink.

 

[routerman]

Adding the PPP multilink would cause one problem, in that only one office could access the central site if both B channels were in use.

However if you are having to ping the site before they can connect I think it may be that the ISDN has gone to sleep.

Check the ISDN status before activating the line.

The command that helps here is:
isdn tei negotiation first-call

Another command that was used to sort out a similar problem was:
isdn send-alerting

 

[chongtl]

If the ISDN has gone to sleep, it will active again once there is traffic from remote to HQ. Right?

Anyway, I will try your command. With your command, what should should I see?

Thanks

 

[routerman]

if you enter SH ISDN STAT

you should see output similar to:

sh isdn stat
The current ISDN Switchtype = basic-net3
ISDN BRI0 interface
Layer 1 Status:
ACTIVE
Layer 2 Status:
TEI = 116, State = MULTIPLE_FRAME_ESTABLISHED
Layer 3 Status:
0 Active Layer 3 Call(s)
Activated dsl 0 CCBs = 0
CCB: callid=0x80DB, sapi=0, ces=1, B-chan=0
Total Allocated ISDN CCBs = 0

This example shows that the ISDN (layer 1 and Layer 2) is active and ready to receive a call.

I have seen some ISDN circuits take down Layer 1, not sure why but it happens. So your router tries to make an outgoing call, fails because L1 is down.

However if you make a call from the other end of the link the ISDN actiavtes L1 and then L2 comes up, assigning a TEI. At this point the remote router can now make outgoing calls.