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Configuring ISDN Logical Interface Properties

You configure ISDN services interface properties at the logical unit level. For information about default settings for ISDN logical interface properties, see the JUNOS Services Interfaces Configuration Guide.

The dialer interface, dln, is a logical interface for configuring dialing properties for a backup ISDN connection. The interface can be configured in two modes:

Multilink mode using multilink-ppp encapsulation. This mode is used when the router supports B-channel bundling (two B-channels connected to provide a 128-Kbps connection) and runs Multilink Point-to-Point Protocol (MLPPP). When the dialer interface (dln) is in multilink mode, the value of n is from 0 through 149. However, you can only configure one dialer interface with multilink-ppp encapsulation. For example, you cannot have both dl1 and dl2 as multilink dialers simultaneously. If you need to have multiple multilink dialers, then the values should be dln.1, dln.2, and so forth.

Normal mode using ppp or cisco-hdlc encapsulation. This mode is used when the router is using one B-channel. When the dialer interface (dln) is in normal mode, the value of n is always is from 0 through 149.

Note: Ensure that the same IP subnet address is not configured on different dialer interfaces. Configuring the same IP subnet address on different dialer interfaces can result in inconsistency in the route and packet loss. Packets may be routed through any of the dialer interfaces that have the same IP subnet address, instead of being routed through the dialer interface to which the ISDN call is connected.

You can configure the following ISDN services logical interface properties:

The dialer interface cannot be configured:

As a backup interface and as a dialer filter simultaneously.
As a backup interface and as a dialer watch simultaneously.
As a dialer watch interface and as a dialer filter simultaneously.
As a backup interface for more than one primary interface.

For specific ISDN configuration information for dial-on-demand routing (DDR) and adding Open Shortest Path First (OSPF) demand circuits to a Services Router, see the JUNOS Routing Protocols Configuration Guide.

For general information about logical unit properties, see Configuring Logical Interface Properties. For general information about family inet properties, see Configuring Protocol Family and Interface Address Properties.

To configure logical interface properties, include the encapsulation statement at the [edit interfaces dln] hierarchy level and the dialer-options statement at the [edit interfaces dln unit logical-unit-number] hierarchy level:



[edit interfaces dln]
encapsulation (cisco-hdlc | multilink-ppp | ppp);
[edit interfaces dln unit logical-unit-number]

dialer-options {

activation-delay seconds;

callback;

callback-wait-period time;

deactivation-delay seconds;

dial-string dial-string-numbers;

idle-timeout seconds;



incoming-map {

caller (caller-id | accept-all);



initial-route-check seconds;
load-interval seconds;

load-threshold percent;

pool pool-name;

redial-delay time;



watch-list {
[ routes ];
}


}


}


}

You can configure the following options:

activation-delay—ISDN activation delay, in seconds. Specify a number from 1 through 4294967295.
callback—Specify the dialer to reject incoming call and call back the caller after a specified wait time.
caller—Specify the dialer to accept a specified caller number or accept all incoming calls.
callback-wait-period—For interfaces configured for ISDN with callback, specify the amount of time the dialer waits before calling back the caller. The default is 5 seconds.
deactivation-delay—ISDN deactivation delay, in seconds. Specify from 1 through 4294967295.
encapsulation—Logical link-layer encapsulation type. For normal mode, specify cisco-hdlc for Cisco-compatible High-Level Data Link control (HDLC) or ppp for Point-to-Point Protocol. For multilink mode, specify multilink-ppp.
dial-string—Phone number to be dialed. Do not include hyphens in number.
idle-timeout—Number of seconds the link is idle before losing connectivity. The default is 120 seconds.

incoming-map—Specify the dialer to accept incoming calls.

Caution: Changing the caller incoming map when a call is connected can create inconsistencies in the route and prevent traffic on a subnet from being transmitted. This is seen when two dialer interfaces are configured and the association of the caller incoming-map from one interface to the other is changed when a call is connected on one of the interfaces. The cause of the inconsistency is that dialer interfaces are pseudo interfaces that are always up, even if not actually connected.

initial-route-check—Allows the router to check whether the primary route is up after the initial startup of the router is complete and the timer expires.
load-interval—Interval used to calculate the average load on the network. By default, the average interface load is calculated every 60 seconds. You can specify an interval from 20 through 180 seconds, configurable in intervals of 10 seconds. For more information about the load interval, see Configuring Bandwidth on Demand.
load-threshold—Bandwidth threshold percentage used for adding interfaces. Another link is added to the multilink bundle when the bandwidth reaches the threshold value you set. Specify a percentage between 0 and 100. When the value is set to 0, all available channels are dialed. The default value is 100.
pool—For logical and physical ISDN interfaces, specify the dial pool. The dial pool allows logical (dialer) and physical (br-pim/0/port) interfaces to be bound together dynamically on a per-call basis. On a dialer interface, pool directs the dialer interface which dial pool to use. On a br-pim/0/port interface, pool defines the pool to which the interface belongs.
redial-delay—Specify the delay (in seconds) between two successive calls made by the dialer (for dialout). The default is 3 seconds.
watch-list—IP prefix of one or more routes. The primary route is considered up if there is at least one valid route for any of the addresses in the watch list to an interface other than the backup interface.

Changing the caller incoming map when a call is connected can create inconsistencies in the route and prevent traffic on a subnet from being transmitted. This is seen when two dialer interfaces are configured and the association of the caller incoming-map from one interface to the other is changed when a call is connected on one of the interfaces.

The cause of the inconsistency is that dialer interfaces are pseudo interfaces that are always up, even if not actually connected.

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