Frame Relay is a standardized wide area network technology that 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, it may be used today in the context of many other network interfaces.

Advantage and Disadvantage of Frame Relay
 Advantage:
*Reasonable wan speed (64Kbps-1.5Mbps)
*Telco is responsible for insuring connectivity
*One serial part at the central site can suppport multiple incoming PVC's
Disadvantage:
*More difficult to configure and manage properly
*No educational tariff is currently available in Alabama.

Where People Use Frame Relay

Frame Relay is designed as a WAN technology primarily for data. When the deployment began, end

users and carriers alike all felt that digital voice (data) could ride on Frame services. However, that

aside, the network and protocols were designed to carry data traffic across the WAN.

A typical Frame Relay connection

The Frame

The frame is a High−level Data Link Control (HDLC)−framed

format, as shown in this figure. The beginning of the frame (as with most HDLC formats) starts with

an opening flag. Next, a two−byte sequence defines the addressing of the frame. This is called the

Data Link Connection Identifier (DLCI). By very nature of the title (DLCI), we can assume that

Frame Relay works at the data link layer.

Frame Relay Speeds

Frame Relay was designed for speeds up to T−1/E−1 (1.544—2.048 Mbps); it later evolved to

speeds of up to 50 Mbps.Actually, few end users have ever implemented Frame Relay at the

higher speeds; this is more of a speed for the carrier community, but the need for stepped

increments has always been a requirement for data transmission.

Frame Relay Access

A link is installed between the end−user location and the network carrier's node. The normal link

speed is T−1, although many locations can and do use Integrated Services Digital Network (ISDN)

or leased lines at lower rates. Some customers may choose to install a local loop at speeds up to

T−3 (45 Mbps approximately) to support higher−speed access and faster data throughput. (In most

implementations, when a customer exceeds 256 Kbps access, the normal installed link for access is

a T−1 in North America at 1.544 Mbps.

A basic frame relay network

From a functional production environment point of view, there are two types of Frame Relays that can be implemented:

1. Permanent Virtual Circuits (PVC) – It is in the formation of logical end-to-end links mapped over a physical network that PVCs are used.
2. Switched Virtual Circuits (SVC) – SVCs are much harder to implement and maintain. Not surprisingly, they are not very common.

Short for permanent virtual circuit, a virtual circuit that is permanently available. The only difference between a PVC and a switched virtual circuit (SVC) is that an SVC must be reestablished each time data is to be sent. Once the data has been sent, the SVC disappears. PVCs are more efficient for connections between hosts that communicate frequently.

Benefits of SVC is Some public Frame Relay services' pricing structures are forcing end users to build star networkseven when the underlying traffic patterns warrant more meshing. Some pricing structures incant

high subscription rates on ports, which result in star and hub−and−spoke configurations.

Frame Relay Selected for Wireless Data on GPRS - General Packet Radio Services (GPRSs) are designed

around the movement of IP datagrams (always−on Internet access) from a cell phone or personal

digital assistant (PDA) to the public Internet or a VPN connection to an intranet.Once this message

gets to the base station, it is then encapsulated into a Frame Relay frame to be carried across the

wireless carrier's network to a router.Our packets are sent to the PCU(Pocket Control Unit) where it is slotted into the Frame Relay service and carried

through the cellular network.

Today: the biggest factors influencing the “useful” life expectancy of Frame Relay as a “live” production environment protocol are the massive increases in data transmission speeds that we are currently seeing in native IP-based networking. Much of these performance gains are in fact directly attributable to the improvements in transmission technologies such as fiber-optic cable and high-speed Ethernet over copper wire over longer distances (MANs & WANs).

Sources:

http://en.wikipedia.org/wiki/Frame_Relay

http://wiki.answers.com/Q/What_are_the_advantages_and_disadvantages_of_frame_relay

http://www.bukisa.com/articles/136_frame-relay

Broadband Telecommunications Handbook