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ISDN bonding for throughput and availablity

Has anyone ever tried to bind 2 ISDN BRI calls together for increased bandwidth BUT had each call calling a different pop so that if the one pop had a problem and the call disconnected the other call would stay up? My ultimate goal is to have as close to 24/7 connectivity as possible and maintain a VPN tunnel as long as at least one pop is up.

4 REPLIES
Cisco Employee

Re: ISDN bonding for throughput and availablity

You can have both the BRIs up 24x7. All you have to do is set 2 "set peers" for the BRIs on your crypto map statement. That way, if first peer (BRI) is down, IPSec will continue on the 2nd BRI, but make sure you use Process Switching i.e. "no ip route-cache" on both BRIs.

HTH

R/Yusuf

Re: ISDN bonding for throughput and availablity

Thanks...can I do that and still have the 256 k virtual pipe when they are both up?

Cisco Employee

Re: ISDN bonding for throughput and availablity

Theoratically YES, if you configure dialer interface and ppp multilink on both BRIs, they will all be part of one virtual link and you will get throughput of 256k, and in the even if 1 BRI goes down, the virtual link will be 128k and IPSec will still continue with 2nd BRI.

My advise is instead of using 2 set peers and peering with physical IP address of the BRIs, you should peer with a Loopback configured on both ends. This way, it is immaterial for IPSec if the BRI goes down, it is only the routing decision which takes place there.

HTH

R/Yusuf

Re: ISDN bonding for throughput and availablity

I really appreciate the info. I forgot to add this last time but last question...Would this only apply if the router was doing the tunnel itself or could a 3002 be behind the router doing the tunnel and still have the tunnel stay up using the same scenario?

TIA!

Travis

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