Frame relay


Frame relay is a communications networking protocol that defines how frames are routed through a fast-packet network based on the address field in the frame.

Frame relay takes advantage of the reliability of data communications networks to minimize the error checking done by the network nodes. This provides a packet-switching protocol similar to but much faster than the X.25 standard. The high speed that you can obtain through frame-relay networks makes them well suited for wide area network (WAN) connectivity. Administrators commonly use frame relay to connect two or more local area network (LAN) bridges over long distances.

The following figure shows the frame format that frame-relay networks use.

Figure 1. Frame format that frame-relay networks use

Frame-relay network architecture is based on the integrated systems digital network (ISDN) packet-mode bearer services. Table 1 shows the standards, either pending or approved, that define the services and the user-to-network interface of frame-relay networks.

Table 1. ANSI and equivalent ITU-T standards
ANSI standard Equivalent ITU-T standard
T1.606, Frame Relay Bearer Services (FRBS) Architectural Framework I.233, ISDN Frame Mode Bearer Service
T1.618, FRBS Core Aspects Q.922, ISDN Extended Data Link (LAP-E)
T1.617, FRBS Signaling Q.933, Frame Mode Bearer Services (FMBS) Signaling
T1.606 Addendum 1, FRBS Congestion Management I.370, ISDN FMBS Congestion Management

The System i™ implementation of frame-relay network support uses protocol headers as defined in the TCP/IP Request for Comment (RFC) 1490.

Frame-relay networks achieve their greater efficiency by minimizing the error checking done by nodes within the network. For Systems Network Architecture (SNA), System i frame-relay support uses IEEE 802.2 logical link control to provide flow control and error recovery functions (see Figure 2).

Figure 2. System i implementation of frame-relay networking

As indicated previously, you can make the connection between the System i platform and the frame-relay network by using X.21, V.35, or RS-449 physical interfaces.

  • Printable PDF
    Use this to view and print a PDF of this topic.

  • Network connections for frame relay
    The direct frame-relay network and the bridged frame-relay network are the two types of network connections that you can configure.

  • Physical environment for frame relay
    The equipment that attaches to a frame-relay network, such as a System i model, is the terminal equipment (TE). A frame-relay network node is a frame handler (FH).

  • Connections for frame relay
    Various options are available for you to configure the frame-relay network connections.

  • Configuration objects for frame relay
    The System i platform uses several configuration objects, such as Network interface description, line description, and controller description, for frame-relay communications.

  • Frame-relay addressing
    For direct connections, data link connection identifiers (DLCIs) provide frame-relay addressing. For bridged connections, local area network (LAN) adapter addresses provide frame-relay addressing.

  • Routing characteristics for frame relay
    The frame-relay network routes frames through the network by examining the data link connection identifier (DLCI) field and then routing the frame to an outgoing link. The network delivers frames to the remote terminal equipment (TE) in the same sequence as they were provided to the network by the local TE.

  • Maximum frame-size parameter requirements for frame relay
    The frame-relay network provider defines and typically establishes a tariff for the frame information field size provided. This size is referred to as N203. Use the N203 value to determine the value specified for the System i maximum frame size (MAXFRAME parameter).

  • Tuning frame-relay performance
    This topic provides information about adjusting parameters for greater network performance.

  • Local management interface
    The System i platform uses the local management interface (LMI) to exchange status information between the frame-relay network (or the frame handler system) and systems attached to the network (terminal equipment).

  • Scenarios: Frame-relay configuration
    These examples show how to configure frame-relay connections.

  • Related information for frame relay
    Listed here is a manual that relates to the Frame relay topic collection. You can view or print the PDF.