ITEM: E5278L

What is Frame relay? Is it available on the RISC/6000 today?

Question:

We've been told to utilize Frame Relay technology to communicate between our
Unisys and RISC System/6000.  Is Frame Relay supported on the RISC/6000?
Can you explain the Frame Relay technology in general terms?

Response:

The RISC/6000 does not support Frame Relay today, so the only solution would
be to go through some other product that attaches to Frame Relay networks.  
Two IBM examples are the 6611 and the Route Expander/2 routers.  

The easiest way of explaining Frame Relay is to compare it with X.25 packet 
switching as we support it today.  Both are packet switching networks where users
share data lines.  Both implement dedicated machines to handle the switching of
packets through the network.  Both are services that users can get from the traditional
telephone providers within their country.

When CCITT X.25 was invented back in the late 1960's, the telephone lines for data communi-
tions were of low speed, poor quality and data often had to be re-transmitted due
to line noise, hits, and so on.  Thus, with CCITT X.25, error correction/detection
was done at each hop made within the network -- meaning the switch had to receive/buffer
each packet, run error correction/detection and either pass the packet on or ask for
re-transmission. In other words, it was a store and forward, hop-to-hop-to-hop
type of system.

Today, phone companies world wide offer higher speed data links and much improved
reliability.  Within the U.S. and much of the western world, much of the transmission
is via high quality lines and, thus, this overhead of error correction/detection
slows the transmission unnecessarily.  Therefore, with Frame Relay, error correction/
detection is done only at the edges of the network -- when the packet(s) is received
at the final destination.  Now, we can take advantage of very high speed links between
switches within the network.  As the switch begins receiving a packet it can begin
passing it along -- no longer awaiting the whole transmission.  

X.25 is available world wide today, so for the near term, it may be the only solution
available between some countries.  Frame Relay is an emerging technology -- still
being standardized right now and only available in limited cities in the U.S.
The relatively slow throughput of X.25 makes it unsuitable for many things AIX users
want to do.  For example, we do not support or recommend NFS, X-Windows, network
install, and so on, across X.25 PSDNs.  Conversely, the speeds that we can expect
with Frame Relay should be suitable for these types of applications.



Support Line: What is Frame relay?  Is it available on the RISC/6000 today? ITEM: E5278L

Dated: October 1993 Category: N/A

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