Chapter Summary

This chapter focused on configuration and troubleshooting issues related to ISDN, its physical cabling, and its related protocols. After reading this chapter, you should understand the common issues confronting administrators in ISDN networks, ISDN encapsulation, and how to use SPIDs. You also have learned about the ISDN connection process, including how to identify interesting data traffic and the protocols used in ISDN.

This chapter covered much of what you need to know to answer exam questions on the topic of troubleshooting ISDN connections. Pay particular attention to the router configurations that were discussed. And remember that when trying to diagnose an ISDN problem, you should consider faulty physical cabling, incorrect telephone company switch configurations, and protocol issues such as q.921 and q.931 signaling.