|  |  | Summary

Now that you have completed this chapter, you should have a firm understanding of the following: ISDN provides an integrated voice/data capability that uses the public switched network. ISDN components include terminals, TAs, NT devices, and ISDN switches. ISDN reference points define logical interfaces between functional groupings, such as TAs and NT1s. ISDN is addressed by a suite of ITU-T standards, spanning the physical, data link, and network layers of the OSI reference model. The two most common encapsulation choices for ISDN are PPP and HDLC. ISDN has many uses, including remote access, remote nodes, and SOHO connectivity. There are two ISDN services: BRI and PRI. ISDN BRI delivers a total bandwidth of 144 kbps within three separate channels. BRI configuration involves the configuration of a BRI interface, an ISDN switch type, and ISDN SPIDs. DDR establishes and releases circuit switched connections as needed.
| Threaded Case Study
Washington School District Project Task: ISDN

In this chapter a new site will be brought into the network. This site is small and will only require connectivity from time to time. The decision has been made to connect it into the WAN core network using ISDN technology. As part of the ISDN configuration and implementation, you need to complete the following tasks:

1. Describe how ISDN will be inserted in the WAN implementation, how data will be sent across the ISDN link, and the benefits of ISDN for a small site.
2. Document the use of ISDN in the WAN design, including providing the following:

> - A drawing of the implementation with all major reference points
> - A description of overall bandwidth available to the site and how data communications will take place
> - A description of all data communications equipment needed to accomplish the implementation

3. Document the router commands needed to implement ISDN on the router and document the resulting changes in the local site access router configurations.
4. Apply the CCNA Certification Exam Learning Objectives to your specific design. This will require a paragraph on how the learning objectives relate to your design. Learning objectives can be grouped together for the purpose of explanation. In this way, you will be studying for their CCNA Certification Exam as you work through the case study.

CCNA Certification Exam Learning Objectives
(*** are explicit CCNA Exam objectives; unmarked are knowledge assumed by the exam):

General

- Describe the user requirement for implementing IDSN to a site
- Describe at what layer of a hierarchical WAN model an ISDN link should be installed

OSI Model

- Define what three layers of the OSI model ISDN standards address.

IDSN

- Describe the 3 data channels used in ISDN BRI and describe their functions
- Describe what ISDN protocols that start with "Q" address
- Describe what ISDN protocols that start with "I" address
- Describe what ISDN protocols that start with "E" address
- Describe the five major devices in a ISDN implementation
- Describe the four major reference points in an ISDN implementation
- Describe the function of Point to Point Protocol in an ISDN Implementation
- Describe why it is important to know the ISDN switch type when configuring an ISDN connection
- Describe the function of SPID numbers and why it is important when configuring and ISDN connection
- State a relevant use and context for ISDN networking***
- Identify ISDN protocols, function groups, reference points, and channels***
- Describe Cisco's implementation of ISDN BRI***

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