Configuring ISDN BRI Directory

Introduction of ISDN

List of Tasks for ISDN BRI Interface Configuration 

Example of configuring ISDN BRI Interface

 

Introduction of ISDN

 Integrated Services Digital Network ((SDN for short) is a new technology developed in 1970s, it provides the complete digital service from terminal user to terminal user, integrating the transmission of voice, data, graphics, video, etc.
    ISDN is different from traditional PSTN in which the information of user is transmitted to exchanger through analogous subscriber loop, then is converted into digital signal through A/D and finally is restored to analog signals through digital switching and transmission network. ISDN resolves the issue of digital transmission of subscriber loop, achieving the digitalization from terminal to terminal. It realizes the smooth transmission of various digital and analog information through the standard digital interface. ITU-T established the service standard of ISDN by standardizing service protocol, which makes the integrated service possible. The protocols of I.430、Q.921and Q.931 and others enables the equipments complying with ITU-T physical interface and software protocol to access to ISDN freely.
   ISDN circuit has two or more B channel with a capacity of 64 Kbps for data transmission and D channel with a capacity of 16 Kbps for signal transmission. Each B channel can be configured as a port. The function of multi-link can execute the collection of ISDN channel. Multi-link means that multiple physical links is integrated into a logic bunch, which broadens the bandwidth of linkage. In addition, it can allocate multiple addresses dynamically, which enables ISDN circuit to be in service when it is needed, maximize the unitization of bandwidth and improving the data transmission efficiency.
    According to ITU-T I.411 suggestion, function cluster (a group of function needed for user‘s accesses to ISDN), reference point (a conceptual point used to classify function cluster), the reference configuration of ISDN user-network interface is formulated, just as shown in the following chart.

Function Cluster includes:

l         Network 1 (NT1): It realizes the function of the first layer of OSI, including the function of transmission of user’s circuit, loop test and competition of D channel, etc.

l         Network 2 (NT2): It is also called Intelligent Network Terminal

l         Terminal equipment (TE1) under category 1: It is also call standard equipment of ISDN. It is the user’s equipment that meets the standards of ISDN interface (such as digital telephone, etc)

l         Terminal equipment under category 2 (TE2): It is also called the equipment of non ISDN standard. It is the user’s equipment that does not meet the ISDN interface standard.

l         Terminal adapter (TA): It enables TE2 to access to ISDN standard interface through adaptation.


The reference point include:

l         R reference point: It is located between ISDN equipment and TA

l         S reference point: It is located between user’s terminal and NT2

l         T reference point: It is located between NT1 and NT2

l         U reference point: It id located between NT1 equipment and circuit terminal equipment

ISDN exchanger can be classified into several types based on their geographic locations, such as European type, North American type, Australian Type and Japanese type. The protocol of these types of routers remain some difference. Nevertheless, ISDN routers made by different manufacturers has a good compatibility, which enables the calling of local BRI configured with the exchanger different from the remote exchanger. In Chinese market, most of ISDN exchangers are manufactured in North America. The command “isdn switch-type” is used to configure the type of ISDN exchanger linked to BRI interface. The negotiation mode of TE1 has two: One is used when the first calling takes place, the other is used when router is started. The coomand “isdn tei-negotiation” is used to configure TE1 negotiation mode of ISDN.

   The command of configuring ISDN BRI can be referred to “ISDN Commands”


List of Tasks for ISDN BRI Interface Configuration

Default encapsulation link layer protocol of ISDN BRI interface is PPP. The following configuration is needed for running IP Protocol at ISDN BRI interface:

l         Configuring ISDN parameter

l         Configuring IP address of ISDN BRI or invoking address negotiation

l         Configuring Dialer map of destination address

l         Configuring link layer Protocol PPP and authentication

l         Configuring DDR parameter

l         Configuring relevant IP router

The detail of the said configuration can be referred to the relevant Configuration Command.

 

Example of configuring ISDN BRI Interface


1. Example 1: Log on network through ISDN, the remote terminal is access server

1)       Demands of Network Establishment

1700 router is linked to access server through ISDN BRI interface and runs IP network protocol.


2) Chart of Network Establishment

3) Steps for Configuration

Configuring the interface of ISDN BRI interface of 1700 router:

configuring global ISDN switch type 

router_config#isdn switch-type basic-5ess

Encapsulating Link Layer Protocol PPPdefault encapsulation protocol is PPP

router_config#interface bri 0/0
router_config_b0/0#encapsulation ppp

Configuring PAP user’s name and password

  router_config_b0/0#ppp pap sent-username 8163 8163
Configuring IP address negotiation of ISDN BRI interface

router_config_b0/0#ip address negotiated

Configuring Dialer Map of NAS

router_config_b0/0#dialer map 202.96.20.133 8163

Configuring Static router to NAS
router_config_b0/0#quit
router_config#ip route 0.0.0.0 0.0.0.0 bri0/0

2. Example 2: The linkage of local ISDN BRI interface and ISDN PRI interface at the center.

1)       The Demand of Network Establishment

1700 router is linked to ISDN PRI interface at the center through ISDN BRI interface and runs IP network protocol.


2) Chart of Network Establishment

3) Steps for Configuration

  Configuring ISDN BRI interface of 1700 router

Configuring global ISDN switch type

router_config#isdn switch-type basic-5ess

Configuring IP address of interface
router_config#interface bri 0/0
router_config#ip address 10.0.0.1 255.0.0.0
Encapsulating link layer protocol PPPdefault encapsulation protocol is HDLC
router_config_b0/0#encapsulation ppp

Configuring user’s name and password of PAP
router_config_b0/0#ppp pap sent-username router mypassword
Configuring Dialer Map to the center of ISDN PRI
router_config_b0/0#dialer map 10.0.0.100 12345678
Configuring static router to the center of ISDN PRI
router_config_b0/0#quit
router_config#ip route 0.0.0.0 0.0.0.0 bri0/0