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Understanding ISDN Standards, Interfaces, and Configurations for DDR, Slides of Computer Networks

Chhattisgarh Swami Vivekanand Technical University Computer Networks

An overview of integrated services digital network (isdn) and dial-on-demand routing (ddr). Learn about isdn standards, interfaces, reference points, and configurations, including isdn bri and pri, isdn functions, and isdn devices. Discover how ddr operates and how to configure it for efficient use.

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ISDN and DDR

Semester 4 – Module 4

Students completing this module should be able to:

Define the ISDN standards used for addressing, concepts, and signaling

Describe how ISDN uses the physical and data link layers

List the interfaces and reference points for ISDN

Configure the router ISDN interface

Determine what traffic is allowed when configuring DDR

Configure static routes for DDR

Choose the correct encapsulation type for DDR

Be able to determine and apply an access list affecting DDR traffic

Configure dialer interfaces

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ISDN and DDR

Semester 4 – Module 4

Students completing this module should be able to: Define the ISDN standards used for addressing, concepts, and signaling Describe how ISDN uses the physical and data link layers List the interfaces and reference points for ISDN Configure the router ISDN interface Determine what traffic is allowed when configuring DDR Configure static routes for DDR Choose the correct encapsulation type for DDR Be able to determine and apply an access list affecting DDR traffic Configure dialer interfaces

Overview

Integrated Services Digital Network (ISDN)
- A network that provides end-to-end digital connectivity to support a wide range of services including voice and data services.
- Allows multiple digital channels to operate simultaneously through the same regular phone wiring used for analog lines, but ISDN transmits a digital signal rather than analog.
- Latency is much lower on an ISDN line than on an analog line.
Dial-on-demand routing (DDR) is a technique developed by Cisco that allows the use of existing telephone lines to form a wide-area network (WAN), instead of using separate, dedicated lines. Public switched telephone networks (PSTNs) are involved in this process. - Used when a constant connection is not needed, thus reducing costs. - Defines the process of a router connecting using a dialup network when there is traffic to send, and then disconnecting when the transfer is complete.

ISDN Standards and Access Methods

The ITU-T groups and organizes the ISDN

protocols according to the following general

topic areas:

E Protocols
- Recommend telephone network standards for ISDN
I Protocols
- Deal with concepts, terminology, and general methods.
Q Protocols
- Cover how switching and signaling should operate. The term signaling in this context means the process of establishing an ISDN call.

ISDN BRI and PRI

BRI
- Two 64 kbps B channels plus one 16kbps D channel
- BRI is sometimes referred to as 2B+D
PRI
- Twenty-three B channels plus one 64kbps D channel
- offers the same service as a T1 or DS1 connection
- Uses a DSU/CSU for T1/E1 connections

ISDN Functions

The following sequence of events occurs during the establishment of a BRI or PRI call: - The D channel is used to send the called number to the local ISDN switch - The local switch uses the SS7 signaling protocol to set up a path and pass the called number to the remote ISDN switch. - The remote ISDN switch signals the destination over the D channel. - The destination ISDN NT-1 device sends the remote ISDN switch a call-connect message. - The remote ISDN switch uses SS7 to send a call-connect message to the local switch. - The local ISDN switch connects one B channel end-to-end, leaving the other B channel available for a new conversation or data transfer. Both B channels can be used simultaneously.

ISDN Devices

Determining the ISDN Interface

To select a Cisco router with the appropriate

ISDN interface, do the following:

Determine whether the router supports ISDN BRI
Determine the provider of the NT1. An NT terminates the local loop to the central office (CO) of the ISDN service provider. In the United States, the NT1 is Customer Premise Equipment (CPE), meaning that it is the responsibility of the customer. In Europe, the service provider typically supplies the NT1.
If the NT1 is built into the CPE, the router should have a U interface. If the router has an S/T interface, then it will need an external NT1 to connect to the ISDN provider.

ISDN Switch Types

Routers must be configured to identify the type of switch with which they will communicate.
Available ISDN switch types vary, depending in part on the country in which the switch is being used.
In addition to knowing the switch type the service provider is using, it may also be necessary to know what service profile identifiers (SPIDs) are assigned by the telco.
A SPID is a number provided by the ISDN carrier to identify the line configuration of the BRI service.
SPIDs allow multiple ISDN devices, such as voice and data equipment, to share the local loop.
SPIDs are required by DMS-100 and National ISDN- switches.

Configuring ISDN BRI

Configuring ISDN PRI

DDR Operation

Dial-on-demand routing (DDR) is triggered when traffic that matches a predefined set of criteria is queued to be sent out a DDR-enabled interface
The traffic that causes a DDR call to be placed is referred to as interesting traffic. Once the router has transmitted the interesting traffic, the call is terminated.
The key to efficient DDR operation is in the definition of interesting traffic. Interesting traffic is defined with the dialer-list command
Dialer lists do not filter traffic on an interface. Even traffic that is not interesting will be forwarded if the connection to the destination is active.

Understanding ISDN Standards, Interfaces, and Configurations for DDR, Slides of Computer Networks

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Download Understanding ISDN Standards, Interfaces, and Configurations for DDR and more Slides Computer Networks in PDF only on Docsity!

ISDN and DDR

Overview

ISDN Standards and Access Methods

protocols according to the following general

topic areas:

ISDN BRI and PRI

ISDN Functions

ISDN Devices

Determining the ISDN Interface

ISDN interface, do the following:

ISDN Switch Types

Configuring ISDN BRI

Configuring ISDN BRI

Configuring ISDN PRI

DDR Operation

Legacy DDR

basic DDR configuration in which a single set of

dialer parameters is applied to an interface.

needed on one interface, then dialer profiles

should be used.

steps:

Static Routes for DDR

• Static routes may be preferred over

dynamic routes due to dynamic routes

constantly dialing to transmit updates

• To forward traffic, routers need to know

what route to use for a given destination.

• To prevent the frequent or constant

activation of the DDR link, configure the

necessary routes statically.