Frame Relay

Frame relay is a uniformed Wide Area Network or known as WAN. It specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure. Frame relay aimed to provide a telecommunication service for cost effective or cheap data transmission for traffic between Local Area Networks or LAN and between end-points in a Wide Area Network or WAN. Frame Relay puts data in variable-size units called "frames" and leaves any necessary error-correction (such as re-transmission of data) up to the end-points.

Frame Relay is a layer-2 protocol used in wide area networking. It uses the

telecommunications provider's packet-switching infrastructure to move data. Frame Relay can provide speeds from 56kbps DS0 up to 43Mbps DS3 connections depending on the capability of the service provider's network.

These are some following terminologies used in Frame Relay:

CIR Committed Information Rate – the minimum level of throughput as

guaranteed by the service provider.

DCE Data Circuit-terminating Equipment – a device on the service provider's

network that connects to the customer's DTE.

DTE Data Terminal Equipment – a device at the customer's site that connects to the service provider's DCE.

DLCI Data Link Connection Identifier – a 10-bit number used to uniquely

identify a virtual circuit end-point on the customer's Frame Relay network.

HDLC High-level Data Link Control – a layer-2 protocol used to control data flow

and provide error detection.

LMI Line Management Interface – a protocol that provides line status and other

management information to the end user of a Frame Relay connection.

PPP Point-to-Point Protocol – an alternative to HDLC.

PVC Permanent Virtual Circuit – a connection between two nodes on a Frame

Relay cloud that allows the exchange of data.

Advantages of Frame Relay:

The main advantage of Frame Relay over point-to-point leased lines is cost.

Frame Relay can provide performance similar to that of a leased line, but with significantly less cost.

Disadvantages of Frame Relay

The two main disadvantages of Frame Relay are slow downs due to network congestion and difficulty ensuring Quality of Service (QoS).

Choosing Equipment

Some Frame Relay providers will include customer equipment like DTE's and routers in the overall package price. If not, Zippy's should plan to purchase equipment from a reputable hardware vendor. The DTE and router can be purchased as separate pieces or as an integrated solution. An integrated package, like a router with a plug-in WAN Interface Card (WIC), can offer easier management, space savings and on epoint of contact for any service related issues.

CHAPTER 10: Integrated Services Digital Network (ISDN)

In this chapter, the concept of the Integrated Services Digital Network (ISDN)  and the following topics shall be discussed:

• ·        Its original goals
• ·        how it can be used
• ·        some of the alternatives

ISDN (Integrated Services Digital Network) is a set of CCITT/ITU standards for digital transmission over ordinary telephone copper wire as well as over other media. Home and business users who install an ISDN adapter (in place of a telephone modem) receive Web pages at up to 128 Kbps compared with the maximum 56 Kbps rate of a modem connection. ISDN requires adapters at both ends of the transmission so your access provider also needs an ISDN adapter. ISDN is generally available from your phone company in most urban areas in the United States and Europe. In many areas where DSL and cable modem service are now offered, ISDN is no longer as popular an option as it was formerly.

There are two levels of service: the Basic Rate Interface (BRI), intended for the home and small enterprise, and the Primary Rate Interface (PRI), for larger users. Both rates include a number of B-channels and a D-channels. Each B-channel carries data, voice, and other services. Each D-channel carries control and signaling information.

The Basic Rate Interface consists of two 64 Kbps B-channels and one 16 Kbps D- channel. Thus, a Basic Rate user can have up to 128 Kbps service. The Primary Rate consists of 23 B-channels and one 64 Kpbs D-channel in the United States or 30 B-channels and 1 D-channel in Europe.

ISDN in concept is the integration of both analog or voice data together with digital data over the same network. Although the ISDN you can install is integrating these on a medium designed for analog transmission, broadband ISDN (BISDN) is intended to extend the integration of both services throughout the rest of the end-to-end path using fiber optic and radio media. Broadband ISDN encompasses frame relay service for high-speed data that can be sent in large bursts, the Fiber Distributed-Data Interface (FDDI), and the Synchronous Optical Network (SONET). BISDN is intended to support transmission from 2 Mbps up to much higher, but as yet unspecified, rates.

Source: http://searchenterprisewan.techtarget.com/definition/ISDN

ISDN is used heavily by the broadcast as a reliable way of switching low latency, high quality, long distance audio circuits. To reiterate, its concept is the integration of both analog or voice data together with digital data over the same network.

When compared to the old telephone dial-up service such as an Internet Service Provider (ISP), an ISDN for Internet Connection is a lot of greater. Using ISDN is just like using a broadband connection because it is as fast. And with such speed, there are innumerable things one can do. Aside from its faster connections which can’t be availed in normal modems, it is direct and with no dialing or engaged tone. It is suitable for gaming, video conferencing and streaming which can also comprise multiple recipients with no interference.

Thus, ISDN is a great technology−driven service that didn't really solve a business (or home) need. ISDN is not widely put into operation. But as we have noticed, there are some clear exceptions. The most notable is the aforementioned video conferencing. Internet access is also a possibility, but ISDN can't compete with xDSL technology in performance for the cost. The ISDN principal rate is used expansively in call centers, utilizing computer telephony integration to make the most of their efficiency.