ISDN BRI- Forcing b2 channel when B1 reaches its full capacity

[Rachna Sharma]

Hi

Can some one please advise.

I have a router running ISDN BRI connection, dial on demand (model 2811)

ISDN BRI has 2 channels, I am wanting to execute the command dialer load-threshold xxx either to use the second B channel if the first B channel reaches its full capacity. The confusion is with the rotary group? Can I not use this command without the rotary-group?  does the physical interface need to be configured as part of rotary group or the dialer interface? What is the use of rotary  group when already on ISDN I have 2 B channels.

BRI config:

interface BRI0/0/0
  bandwidth 64
 no ip address
 encapsulation ppp
 no ip mroute-cache
 dialer pool-member 1
 isdn switch-type basic-net3
 isdn point-to-point-setup
 ppp authentication chap
end

dialer interface config:

interface Dialer1
 bandwidth 64
 ip address x.x.x.x
 ip nat inside
 ip virtual-reassembly
 encapsulation ppp
 no ip mroute-cache
 ip ospf cost 30000
 dialer pool 1
 dialer remote-name abcdef
 dialer idle-timeout 300
 dialer string xxxxx
 dialer watch-group 30
 dialer-group 2
 no cdp enable
 ppp authentication chap
end

Regards,

[Georg Pauwen · Accepted solution]

Hello,

as far as I recall, rotary groups are used for multiple physical BRI interfaces. In your case, with only one physical BRI, all you need is the two commands below:

ppp multilink
dialer load-threshold load [outbound | inbound | either]

[Rachna Sharma]

Thank you Georg for answering.

Can I ask how do I verify if B1 B2 are in use.

Regards

[Rachna Sharma]

Thanks I tested it with min threshold 1 and could see in debug both bri x/x/x:1 and : 2 were were connected

[Georg Pauwen]

Hello,

the exec command 'show isdn status' tells you the status of the layers. In he 'Later 3 Status' section check for the line 'Number of available B-channels =', which gives you the number of B channels that are not being used. Keep in mind that this line might not appear until a call is connected.

[Rachna Sharma]

I put the threshold minimum and pinged the dialer . At the same time did the debugs too.

 I did the sh isdn active which showed me two calls out instead of one

[Georg Pauwen]

Hello,

setting the dialer load-threshold to 1 immediately brings up both B channels. If you want to bring up the second only when the first one is fully utilized, use a value of 250 or higher...

[Rachna Sharma]

I am using 255, that was done to test only