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ISDN Call to Nearest MPLS PE and HQ , redundancy test.


I've a situation where I've two ISDN call backup using 1 BRI for my branch connection. First, the call will go to a nearest MPLS node, if this is failed, its will call to a second dialer string to my HQ. (there is 2 router at HQ, one connected to MPLS (3800), and second for ISDN and VOIP call(3640)).

The problem occur when everytime the ISDN call to MPLS, everything are OK. Then, when I disconnect the isdn dial to MPLS ( so it will call to HQ ), I can't access HQ.

If at first I call HQ and then MPLS, everything ok. But if I call back HQ after MPLS call, it can't route. From HQ 3800 router, I can see the route keep on searching at MPLS cloud and back to HQ router (looping).

At branch, the routing are to BRI1/0 :-

ip route BRI1/0

ip route BRI1/0

interface BRI1/0

ip unnumbered Loopback1

encapsulation ppp

dialer string 123456

dialer string 789011

dialer load-threshold 1 either

dialer-group 1

isdn switch-type basic-net3

isdn point-to-point-setup

ppp authentication chap callin

ppp chap hostname xxxxx

ppp chap password xxxxx

ppp multilink

ppp multilink load-threshold 1 either


**Both string configure at int BRI1/0, no int dialer used.

At HQ ISDN router i put this route :-

ip route 192.168.x.x 200

At HQ 3800 router i put :-

ip route 182.x.x.x 220

(182.x.x.x = MPLS node ip)

Need helps. Thanks.


Re: ISDN Call to Nearest MPLS PE and HQ , redundancy test.

I suspect it is the problem of the routes at HQ will not show up as preferred. Can you show the routing tables at HQ GW in each cases ?

And will the floating static redistributed into the dynamic routing protocol and communicate to both routers (ISDN & 3800) at HQ ?

In your case, you use two floating static at two routers, you have to ensure when you learn the static route via dynamic routing protocol, the AD will be changed and not able to compare to the floating static.

Try to check the cost and fine tune the cost of both floating static.

If the problem still exists, please also provide the routing config. at both HQ routers.

Hope this helps.

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