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New Member

ISDN DDR load balancing.

One of our client is connected through Leased line and ISDN as back up. The customer wants the configuration to be done in such a way that when the load in the Leased line increases 75% it should trigger "only one" channel of ISDN and should do load balance between the two. Now suppose if the Leased line goes down then the other channel of ISDN also come up. How shall I go with this. I can give 'backup load' and 'dialer load-threshold' commands, but the problem is that when one channel is triggered because of load in serial and if the load at that time on the isdn increases above the threshold value configured, then the other channel will also be triggered. that should'nt happen. only one channel should come up if the load increases inthe serial irrespective of the load in the ISDN. Can any one help me on how to go with this.

Thank you,


  • Other Network Infrastructure Subjects
New Member

Re: ISDN DDR load balancing.

config t

int serialX

backup interface isdnX

backup delay x y

backup load 191 !i think load is x/255 so 191 should roughly be 75%

interface isdnX

dialer load-threshold 128 either !50% of first b channel be loaded for the second to come up


AFAIK you can't really tell the isdn to only bring up one channel only when the primary interface is down. I would just jack up the dialer load-threshold so it only dials the second channel if really needed.

Also if you primary interface is a subinterface you can't track the load.