FRAME RELAY

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. Frame relay is also a protocol standard for LAN internetworking which provides a fast and efficient method of transmitting information from a user device to LAN bridges and routers.

The Frame Relay protocol uses a frame structured similar to that of LAPD, except that the frame header is replaced by a 2-byte Frame Relay header field. The Frame Relay header contains the user-specified DLCI field, which is the destination address of the frame. It also contains congestion and status signals which the network sends to the user.

Virtual Circuits

The Frame Relay frame is transmitted to its destination by way of virtual circuits (logical paths from an originating point in the network) to a destination point. Virtual circuits may be permanent (PVCs) or switched (SVCs). PVCs are set up administratively by the network manager for a dedicated point-to-point connection; SVCs are set up on a call-by-call basis.

Dedicated, High-Speed Internet Connection for Your Business

Frame Relay service gives you a direct connection to the Internet with a high-speed, dedicated line. As a step above DSL business services, it is most appropriate for businesses located outside metropolitan areas needing highly reliable Internet connectivity

Advantages of Frame Relay Service

• Scalable access speeds ranging from 56Kbps to 42Mbps.
• Committed information delivery rates (CIR) up to 10Mbps.
• Flat rate pricing (no mileage or usage charges apply).
• LAN-to-LAN connectivity that protects the integrity of network data.
• Easy migration path for existing LANs or SNA private-line networks, protecting existing or future investments.
• Support for multiple communication architectures, including hierarchical and client/server networks.
• Mature technology with industry-wide support, service and availability.
• Provides a migration path to ATM.

Enhanced Features

• High-Speed Frame Relay
• Frame to ATM Service Internetworking
• Complementary Service Providers
• Multicast Service

Applications

• High-speed Internet access
• LAN/WAN interconnection
• SNA transport
• Client/server transactions
• File and data transfers
• Remote Database Access

Frame Relay Devices

There are two types of devices attached to a frame relay WAN, DTE, and DCE.

·         DTEs (Data Terminal Equipments) are generally terminating equipments for a specific network. They are typically located on the customer's premises and include: personal computers, terminals, bridges, and routers.

·         DCEs (Data Circuit-terminating Equipments) are carrier owned internetworking devices and they provide clocking and switching services in a network.

Physical layer component and link layer component connect the DTE and DCE devices. A physical layer component defines the electrical, functional, mechanical, and procedural specifications while a link layer component defines the protocols.

Frame Relay vs ATM

Similarities between the frame relay and ATM:

·         They are virtual circuit based.

·         They are NBMA technologies.

·         They have burst rate features.

·         They have congestion avoidance techniques.

·         They have traffic shaping or management techniques.

·         FECN of frame relay is equivalent to the EFCI of ATM.

·         BECN of frame relay is equivalent to the RRM of the ATM.

Differences between frame relay and ATM:

·         Frame relay is not cell based while ATM is cell based.

·         Frame relay is not asynchronous while ATM is asynchronous.

·         Frame relay does not have a LANE deployment while ATM does.

·         Frame relay LMI is completely different from ATM ILMI.

References:

• http://en.wikipedia.org/wiki/Frame_Relay
• http://www.tech-faq.com/understanding-frame-relay.html
  http://www.dcbnet.com/notes/framerly.html
  http://www.protocols.com/pbook/frame.htm
  http://www.hubris.net/services/descriptions/frame_relay.html