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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:

You can configure the following ISDN services logical interface properties:

The dialer interface cannot be configured:

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:

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.

Configuring an ISDN Dialer Interface as a Backup Interface

Configuring the ISDN interface as a backup interface ensures continuous network connectivity. The Services Router can be configured to fail over to the ISDN interface if the primary connection experiences interruptions in Internet connectivity.

To configure an ISDN interface as the backup interface, include the backup-options statement at the [edit interfaces interface-name unit logical-unit-number] hierarchy level:

[edit interfaces interface-name unit logical-unit-number]
backup-options {
interface dln.0;
}

interface-name is the primary interface. The backup interface is specified as dln.

Example: Configuring an ISDN Interface as the Backup Interface

The following example illustrates a backup configuration using a primary serial interface, two dialer interfaces, and a physical ISDN interface.

See Figure 51 for the topology used for this example.

Figure 51: ISDN Backup Topology

Image g017025.gif

Configure dialer interface dl0 as the backup interface on the primary serial interface t1-4/0/1:

Configuration on the Primary Serial Interface

[edit interfaces]
t1-4/0/1 {
encapsulation ppp;
backup-options {
interface dl0.0;
}
unit 0 {
family inet {
address 192.168.10.2;
}
}
}

Configuration on the Dialer Interface

[edit interfaces]
dl0 {
encapsulation ppp;
unit 0 {
dialer-options {
pool 10;
dial-string 5552222;
activation-delay 10;
deactivation-delay 10;
}
family inet {
address 172.20.10.2 {
destination 172.20.10.1;
}
}
}
}

Configuration on the Physical ISDN Interface

[edit interfaces]
br-1/0/0 {
isdn-options {
calling-number 5558888;
spid1 51255511110101 5551111;
spid2 51255511120101 5551112;
switch-type ni1;
t310 70;
}
dialer-options {
pool 10 priority 3;
pool 2 priority 25;
}
}

Applying the Dial-on-Demand Dialer Filter to the Dialer Interfaces

Dial-on-demand routing (DDR) links two sites over a public network and provides bandwidth. An ISDN connection allows an ISDN line to be activated only when there is network traffic configured as an “interesting” packet. An interesting packet is defined using the firewall filter feature of the Services Router.

To configure DDR, you configure the dialer interface as a passive static route with a lower priority than dynamic routes. If the dynamic route is lost, and a packet destined for that IP address is received, the dialer interface initiates an ISDN connection and sends the packet over it. When no new packets are sent to the destination, the dialer interface initiates an inactivity timer. The ISDN connection is terminated when the timer expires.

There are three steps to configuring dial-on-demand connectivity:

To define the filter, include the dialer-filter interesting-traffic statement at the [edit firewall family inet] hierarchy level.

To configure the firewall rule, include the term and from statements at the [edit firewall family inet dialer-filter filter-name] hierarchy level.

To apply the filter to the dialer interface, include the filter dialer statement at the [edit interfaces dln unit logical-unit-number family family] hierarchy level.

Example: Applying the Dialer Filter

The following example illustrates a dialer filter configuration configured at the [edit firewall family inet] hierarchy level and applied to a physical interface and a dialer interface.

See Figure 52 for the topology used for this example.

Figure 52: Dialer Filter Topology

Image g017022.gif

Configuration for the Dialer Filter

[edit firewall family inet]
dialer-filter interesting-traffic {
term 1 {
from {
destination-address {
100.0.0.50/32;
}
}
then note;
}
}

Configuration on the Dialer Interface

[edit interfaces]
dl0 {
encapsulation ppp;
unit 0 {
dialer-options {
pool 1;
dial-string 350100;
}
}
family inet {
filter {
dialer interesting-traffic;
}
address 50.2.0.1/24;
}
}

Configuring Bandwidth on Demand

You can define a bandwidth threshold for network traffic on the Services Router using the dialer interface and ISDN interfaces. Initially, only one ISDN link is active and all packets are sent through this interface. When a predefined bandwidth threshold is reached on this interface, the dialer interface activates another ISDN link and initiates a data connection.

To configure bandwidth on demand, perform the steps in the following sections to configure the dialer interface and the physical ISDN interfaces:

Configuring the Dialer Interface

To configure the dialer interface for bandwidth on demand, include the encapsulation multilink-ppp statement at the [edit interfaces dln] hierarchy level:

[edit interfaces]
dln {
encapsulation multilink-ppp;
}

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

[edit interfaces dln unit logical-unit-number]
dialer-options {
dial-string dial-string-numbers;
load-interval seconds;
load-threshold percent;
pool pool-name;
}

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

[edit interfaces dln unit logical-unit-number]
family family {
mtu bytes;
negotiate-address;
filter {
filter-name;
fragment-threshold bytes;
mrru bytes;
ppp-options {
chap {
access-profile name;
}
}
}
}
}
}

You can configure the following unit properties:

Configuring the ISDN Interface

To configure the ISDN interface for bandwidth on demand, include the pool statement at the [edit interfaces br-pim/0/port dialer-options] hierarchy level:

[edit interfaces br-pim/0/port]
dialer-options {
pool pool-name;
}

Each ISDN interface must use the same dialer pool name to participate in the bandwidth-on-demand configuration.

Example: Configuring Bandwidth on Demand

Figure 53 illustrates a bandwidth-on-demand configuration using multiple physical ISDN interfaces.

Figure 53: Bandwidth-on-Demand Topology

Image g017023.gif

Configuration for the Dialer Interface

[edit interfaces]
dl0 {
encapsulation multilink-ppp;
unit 0 {
dialer-options {
pool 10;
dial-string 5552222; #Phone number to be dialed
load-threshold 95;#Dial more ISDN if load exceeds 95% of
#current capacity
}
fragment-threshold 1024; #Allowed only when dialer is in multilink mode
mrru 1500; #Allowed only when dialer is in multilink mode
encapsulation multilink-ppp;
rtp {
f-max-period 100;
queues q3;
}
}
family inet {
negotiate-address;
}
}

Configuration for the First Physical ISDN Interface

[edit interfaces]
br-1/0/0 {
isdn-options {
switch-type ni1;
}
dialer-options {
pool 1;
}
}

Configuration for the Second Physical ISDN Interface

[edit interfaces]
br-1/0/1 {
isdn-options {
switch-type ni1;
}
dialer-options {
pool dialer-pool1;
}
}

Configuring Dial-In and Callback

You can configure dial-in on the dialer interface to permit incoming calls. Using dial-in, all incoming calls on a BRI interface are mapped to a dialer interface based on a caller ID. The incoming call’s caller ID is compared against all caller IDs configured on all dialers to find the valid match. Multiple caller IDs can be configured on a dialer interface. The same caller IDs cannot be configured on different dialers.

Instead of accepting incoming calls, you can configure the dialer interface to call back the caller. When callback is configured, the call is rejected, and after a brief delay the caller is called back using the dial-string configured on the dialer interface. Multiple dial-strings cannot be configured on a dialer when callback is configured.

To configure dial-in or callback, perform the steps in the following sections to configure the dialer interface and the physical ISDN interfaces:

Configuring Dial-In

To configure the dialer interface for dial-in operation, include the incoming-map statement with options at the [edit interfaces dln unit logical-unit-number dialer-options] > hierarchy level:

[edit interfaces dln unit logical-unit-number]
dialer-options {
incoming-map {
caller (caller-id | accept-all);
}
}
}

Include the option accept-all to accept all incoming calls. You can configure the accept-all option for only one of the dialer interfaces associated with an ISDN physical interface. The dialer interface with the accept-all option configured will be used only if the incoming call’s caller ID does not match against the caller IDs configured on other dialer interfaces.

Include the caller caller-id statement to configure the dialer interface to accept calls from a specific caller ID. You can configure a maximum of 15 caller IDs per dialer interface.

The same caller ID cannot be configured on different dialer interfaces. However, you can configure a subset of the caller ID configured on another dialer interface. For example, you can configure the caller IDs 14085551515, 4085551515, and 5551515 on different dialer interfaces.

Disabling Dial-In

When dial-in is configured on the Services Router, incoming ISDN calls are accepted by the Services Router. However, you can configure the Services Router to reject all incoming ISDN calls when dial-in is configured.

To configure the Services Router to reject incoming ISDN calls, include the reject-incoming statement at the [edit system processes isdn-signaling] hierarchy level:

[edit system processes isdn-signaling]
reject-incoming;

For more information about disabling dial-in, see the JUNOS System Basics Configuration Guide and the J-series Services Router Basic LAN and WAN Access Configuration Guide.

Configuring Callback

To configure the dialer interface to call back a specific caller, include the caller caller-id statement and the callback statement at the [edit interfaces dln unit logical-unit-number dialer-options] hierarchy level:

[edit interfaces dln unit logical-unit-number]
dialer-options {
incoming-map {
caller caller-id;
callback;
callback-wait-period time;
}
}

Include the optional callback-wait-period statement to change the time at which the dialer interface calls back the caller. The default period is 5 seconds.

Before configuring the callback on a dialer interface, ensure that:

Example: Configuring Dial-In and Callback

The following illustrates configurations for dial-in and callback operations.

Configuration to Accept All Incoming Calls

[edit interfaces]
dl0 {
encapsulation ppp;
unit 0 {
dialer-options {
dial-string 7031231282;
incoming-map;
accept-all;
}
pool 2;
family inet {
address 10.1.1.2;
}
}
}

Configuration to Accept Calls from a Specific Caller ID

[edit interfaces]
dl0 {
encapsulation ppp;
unit 0 {
dialer-options {
incoming-map {
caller 14082711234;
}
pool 1;
family inet {
address 20.1.1.1;
}
}
}
}

Configuration to Call Back Calls from a Specific Caller ID

[edit interfaces]
dl0 {
encapsulation ppp;
unit 0 {
dialer-options {
incoming-map {
caller 14082711234;
}
callback;
callback-wait-period 2;
pool 1;
family inet {
address 20.1.1.1;
}
}
}
}

Configuring Dialer Watch

Dialer watch is a feature that integrates backup dialing with routing capabilities and provides reliable connectivity without relying on “interesting” packets to trigger outgoing ISDN connections. With dialer watch, the Services Router monitors the existence of a specified route and if the route fails, the dialer interface initiates the ISDN connection as a backup connection.

To configure dialer watch, perform the steps in the following sections to configure the dialer interface and the physical ISDN interface:

Configuring the Dialer Interface

To configure the dialer interface for dialer watch, include the following statements at the [edit interfaces dln] and the [edit interfaces dln unit logical-unit-number] hierarchy levels:

[edit interfaces]
dln {
encapsulation (cisco-hdlc | multilink-ppp | ppp);
hold-time (up | down) milliseconds;
unit logical-unit-number {
dialer-options {
activation-delay seconds;
deactivation-delay seconds;
dial-string dial-string-numbers;
hold-time seconds;
initial-route-check seconds
pool pool-name;
watch-list {
[ routes ];
}
family family {
ip-address;
}
}
}
}

Configuring the Physical Interface

To configure the physical interface for dialer watch, include the pool statement at the [edit interfaces br-pim/0/port dialer-options] hierarchy level:

[edit interfaces]
br-pim/0/port {
dialer-options {
pool name;
}
}

Each physical interface must use the same pool to participate in dialer watch.

Example: Configuring Dialer Watch

The following example illustrates a dialer watch configuration using one physical interface and one dialer interface.

See Figure 54 for the topology used in this example.

Figure 54: Dialer Watch Topology

Image g017024.gif

Configuration for the Physical Interface

[edit interfaces]
br-2/0/0 {
isdn-options {
switch-type ntdms100;
}
dialer-options {
pool 1 priority 1;
}
}

Configuration for the Dialer Interface

[edit interfaces]
dl0 {
unit 0 {
dialer-options {
pool 1;
dial-string 384030;
watch-list {
2.2.2.2/24;
3.3.3.3/24;
}
}
family inet {
address 40.0.0.1/8;
}
}
}
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