ISDN-3

 There are some issues when using ISDN :
 * __Implementation issues__**
 * Reliability** - As applications become more sophisticated and require more bandwidth, the connection over modem will become poor. If it be used to an entire corporate LAN on the Internet, a modem connection becomes a serious bottleneck. That completely different something is digital signaling, in the form of Integrated Services Digital Network (ISDN). Using the same copper phone line that modems use, ISDN delivers a five-fold speed improvement (up to 128 Kbps) and provides essentially perfect transmission reliability. And ISDN can mesh into other digital technologies, such as Frame Relay and ATM, making possible future speeds several times higher even than 128 Kbps.
 * Cost** - V ideo- conferencing calls over ISDN circuits will involve to making six or more ISDN connections to provide sufficient bandwidth for high-quality business video calls. These calls proved expensive (because so many circuits were required and the historically high cost of ISDN calls) and unreliable (due to the multiple circuits and also multiple carriers involved in international calls).
 * QoS** - Can be used with RTP (Real-Time Protocol) header compression that use for carrying newer multimedia traffic including packetized audio and video which already been used for application like VOIP (Voice Over IP), video-conferencing, distance learning program. Although the IP also can be use in the video- conferencing, but it also use UDP protocol not like ISDN that use H.221 (International Telecommunication Union standard for frame structure of video-conferencing).
 * Redundancy** - Lack in one or more of an end-point ISDN lines experiences problems, the end- points’ ability to communicate will be blocked or impacted.
 * Security** - Security issues are a prime concern for digital transmissions. Although data encryption schemes can alleviate the problem, other security issues prevail. The National Security Agency has approached the FCC (// Federal Communications Commission //) with legislation that would make possible electronic surveillance of all digital transmissions. The underlying reason stems from the possible use of the telecommunications system by criminal organizations. Without a means to monitor encrypted network traffic, there could be no detection or intervention of illegal activities taking place over the public network.


 * __Conclusion__ **

ISDN is a great WAN technology. However, if we have the option of DSL or cable modem, those are faster, cheaper technologies. We would still use ISDN if you needed voice, video, data, and special application services, which are not provided by DSL and cable modems. There is and for years has been a global push to become a digital world. The main evidence of the digital age is the internetworking of computers, providing access to a wealth of resources and information. ISDN technology, although plagued by political issues, is a cost-effective means to connect communication equipment of all types. As more of the compatibility issues are resolved, ISDN services will increasingly become the service of choice for businesses and residential customers. The rise in popularity should drive down equipment costs and make connection devices readily available off-the-shelf. Although other digital services are competitive, most require expensive dedicated lines or possess inherent shortcomings like slow speed. ISDN technology is standardized and provides dynamic high speed end-to-end digital connectivity over the existing worldwide telephone network. ISDN continues to evolve with broadband ISDN availability in the near future. With ATM-based technology providing B-ISDN transmission speeds up to 600 Mbps or more, one would be hard-pressed to find a viable affordable alternative.

http://www.ralphb.net/ISDN/history.html - history http://en.wikipedia.org/wiki/ISDN - about isdn  http://www.conceptron.com/articles/isdn.html http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Routing-Basics.html#wp1020619 http://users.tkk.fi/ayasmin/ISDN_internet.html http://www.mylibnet.org/nissat/vol14/isdn.htm http://www.idstech.com/overview.htm http://www.jet.net/isdn/isdnintro.html Morgan.Kaufmann, Network Analysis Architecture and Design. 3rd.Edition. Jun 2007
 * References**

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