Frame Relay
bintec User’s Guide
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FR Menu
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End Systems
End systems are typically end-user devices that make use of the underlying
Frame Relay network. Depending on the application running on the end sy-
stem, bandwidth requirements of end systems on the LAN can differ. Some
applications generate large amounts of intermittent bursty traffic (typical of
data applications, telnet, ftp, www) while others (like voice or video) require
a constant bitrate.
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Frame Relay Routers
Frame Relay Routers are used to connect point–to–multipoint networks
(LANs) to a public (or private) Frame Relay network. It is the router’s job to
encapsulate LAN data into Frame Relay frames to be transported over the
network link. A Frame Relay Router encapsulates LAN frames in Frame
Relay frames and feeds those frames to a Frame Relay Switch for trans-
mission across the network. A Frame Relay Router also receives Frame
Relay frames from the switch, strips the Frame Relay frame off each frame
to produce the original LAN frame, and passes the LAN frame on to the end
device. A Frame Relay Router communicates directly with one or more Fra-
me Relay Switches to negotiate the opening/closing of virtual circuits and
to control network congestion.
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Frame Relay Switches
Switches are typically owned by public network providers but may be ow-
ned by private sites implementing private Frame Relay Networks. Aside
from the FECN (Forward Explicit Congestion Notification), BECN (Back-
ward Explicit Congestion Notification), and DE (Discard Eligibility) frame
fields (used for congestion management) the content and final destination
of individual frames is of no interest to the switch. Using a simple mapping
scheme, frames are passed from one interface to another. The DCLI (Data
Link Connection Identifier) frame field assigns the vitual connection used.
Frame Relay Services
Frame Relay access can be purchased in a variety of configurations depending
of your site’s needs. Characteristics of the service you will receive include:
1.
The type of physical connection you have to the Frame Relay network,
ISDN or X.21.
2.
The amount (from 56Kbps up to 2Mbps) and type of bandwidth available
via this connection; this will include your guaranteed and excess rates. See
CIR, CBR, and EBR earlier.
