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New Member


Dear all,

We have a router where leased line is primary link , VSAT is secondary & ISDN is tertiary link.

VSAT has output in form of ethernet which is terminated on L2 switch . Whenever leased line goes down , traffic gets shifted on VSAT but problem is that ISDN keeps on dialing intermittently even when leased line is UP. This could be due to because backup interface is not defined on serial port of leased line .But if I define this , i cannot use VSAT as secondary backup.

Can somebody help?




Re: backup

Could you please provide the config ?

We can use floating static with different metric to control the sequence of each path.

Re: backup

Hi Aman

Do u want to use the isdn as a backup for VSAT link ??


New Member

Re: backup

I want to use ISDN when VSAT goes down..

Please find the config .


Re: backup

What I believe the ISDN will up & down frequently, it was due to the permitted list is permitting all IP packet. It means it will also include the broadcast. If there is a broadcase, it will trigger the ISDN to dial to remote. You have to specific the interesting packet that will use this link.

According to the config, I suggest to have below dialer-list :

dialer-list 1 protocol ip

And, will the remote side dial to this router or it is a one way dialer ? i.e. will the ISDN connection triggered by remote ?

Moreover, please also provide the "sh ip route", I suspect you are using some GW which is not directly connected to the route for VSAT link. And, you don't need to configure three routes w/ floating static, only need to configure it on VSAT & ISDN link. Otherwise, the default route will be the forth path for the traffic.

Hope this helps.