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Effective Is Frame Relay?
Relay provides a number of benefits over alternative technologies:
low overhead combined with high reliability; network scalability,
flexibility and disaster recovery; interworking with other
new services and applications such as ATM.
wide area network switching technologies, such as X.25 packet
switching and TDM circuit switching, will remain important
where line quality is not as good, when the network itself
must guarantee error-free deliver, or when the traffic is
intolerant of delay.
us now compare Frame Relay with other communication technologies.
Relay Vs Leased Line
Leased line and Frame Relay are two connection technologies
normally used to provide permanent, always-on network connections
for end user organizations.
a leased line, a permanent 24 hour per day data connection
is established between the user's site and the Internet
Service Provider (ISP). This is provided in multiples of
64Kbps (kilo bits per second) with the current normal range
of 64K to 2Mbs (million bits per second). The leased line
is itself provided by the appropriate telephone company
they must have infrastructure or access to infrastructure
at both sites. Leased lines are fine if single connections
are needed but are inefficient when an organization needs
multiple connections because all sites may need leased lines
to all other sites.
Relay works on a different principle connections from user
sites are made to the Frame Relay "cloud"--and
then any connection can be set up within the cloud to other
sites. So with the Frame Relay connection there are two
connections built in (PVCs or Private Virtual Circuits),
with traffic taking the most appropriate route to other
sites on the Internet or if one path is not available, taking
the other route.
sites connected by leased lines would mean lots of leased
lines, which would be difficult to manage and expensive
to both run and alter. With Frame Relay, each site has a
connection to the Frame Relay cloud and other connections
are "virtual" connections within the cloud. It
is completely secure and cost effective.
Relay Vs X.25
The biggest difference between Frame Relay and X.25 is that
X.25 guarantees data integrity and network managed flow
control at the cost of some network delays. Frame Relay
switches packets end to end much faster, but there is no
guarantee of data integrity at all. Frame Relay is cost
effective, partly due to the fact that the network buffering
requirements are carefully optimized. Compared to X.25,
with its store and forward mechanism and full error correction,
network buffering is minimal. Frame Relay is also much faster
than X.25: the frames are switched to their destination
with only a few byte time delay, as opposed to several hundred
milliseconds delay on X.25.
evolution beyond the X.25 protocol, Frame Relay is a network
interface standard based on statistical multiplexing. By
combining the flexibility of X.25 packet protocol with the
performance of private lines, Frame Relay Service can move
data much more efficiently than the packet protocol. In
fact, Frame Relay Service streamlines the processing steps
associated with X.25 error detection/correction and routing
Relay technology takes advantage of highly accurate digital
networks with their reduced line errors and intelligent
network end point devices with their end-to-end error checking
protocols. The reduced per packet processing time allows
you to process more user data. Also, the upgrade to Frame
Relay Service is simple and cost effective because Frame
Relay Service is based on the HDLC protocol, which is popular
among LAN bridges, routers and other communications devices.
Relay Vs. Asynchronous Transfer Mode (ATM)
ATM is normally utilized for high bandwidths of 34 Mbps
and upwards. There are two ways that corporate networks
can afford such bandwidths; in the LAN or campus, or set
up their own WAN transmission networks. If corporations
have to lease WAN bandwidth to interconnect LANs, Frame
Relay is the natural choice. First, at speeds of 2 Mbps
and below, Frame Relay is more bandwidth efficient than
ATM. Access and switching equipment is more mature, more
plentiful and less costly.
leased bandwidth can be augmented with bandwidth from public
Frame Relay services for maximum cost efficiency. There
is little doubt that Frame Relay will be an access protocol
to the ATM networks of tomorrow standards are now defining
the interface for Frame Relay to ATM internetworking. Investment
in Frame Relay internetworking is protected as networking
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