ISDN configuration: PPP multilink and dialer load-threshold

Wassim Aouadi · ‎07-08-2009

hi,

I'm getting confused while trying to understand the relationship between PPP Multilink, dialer load-threshold and dialer idle-timeout here.

here's the DDR dialer profile configuration :

interface Dialer200

description **** Dialer SSE 1 ****

ip address 192.168.200.9 255.255.255.252

encapsulation ppp

dialer pool 200

dialer remote-name yyy

dialer idle-timeout 60 either

dialer string 77801001

dialer load-threshold 1 inbound

dialer-group 1

no fair-queue

ppp authentication chap callin

ppp chap hostname xxx

ppp chap password zzz

ppp multilink

anyone could give me an explanation?

Giuseppe Larosa · ‎07-08-2009

Hello Wassim,

PPP multilink in ISDN scenario means using multiple bearer B channels as needed and as many as they are available on the physical interfaces BRI or PRI associated with the pool 200.

dialer load-threshold 1 inbound says the router to add additional B channel(s) as soon as the call is setup, because usage of 1 is the minimum (it is expressed as 1-255 with 255 meaning full loaded)

dialer idle-timeout 60 either

means that the time the call is held up without seeing any interesting packet on the link to be tramsmitted or received (either) is 60 seconds

The interesting traffic that can trigger the call and that is checked to decide if keeping up the call is defined by

dialer-group 1

tha points to dialer-list 1

Hope to help

Giuseppe

Wassim Aouadi · ‎07-08-2009

hi Giuseppe,

About the "dialer load-threshold" in a PPP multilink context, I found the following in Dial Technology Reference Guide:

"When multilink PPP is configured, the dialer load-threshold 1 command no longer keeps a multilink bundle of n links connected indefinitely"

so I guess "dialer load-threshold 1 inbound" has a special meaning here?

Giuseppe Larosa · ‎07-08-2009

Hello Wassim,

inbound = received

but I'm not sure if in this case what will be the effect if this is enough to revert to old behaviour.

I've gone to 12.4 Dial reference

http://www.cisco.com/en/US/docs/ios/dial/command/reference/dia_d1.html#wp1013318

read it carefully it looks like that only using an high idle-timeout you can keep up multiple B channels.

The reason are the bills to be payed: customers have asked Cisco to change the behaviour to reduce expenses in countries with no flat rate (for example in Germany ISDN is flat rate)

Hope to help

Giuseppe