Ref: 10820004
Title: IB/3 SIO Aggregate Throughput
Date: 5/4/90

Copyright 3Com Corporation, 1991.  All rights reserved.

The maximum aggregate throughput of all synchronous SIO cards that
may be placed into an IB/3, with the exception of the ITC/M (Intelligent
T-1 Controller for Multibus), is 84 Kbps.

Synchronous SIO cards that may be installed in an IB/3 include the
SIO-SMS (RS-232 male DB-25 conectors), the SIO-V.35 (V.35 female
connectors), and the SIO-422S (RS-449 male DB-37 connectors).  The
aggregate speed of these cards is the same whether the system in which
they are installed is an IB/3 or another Series/1-based product.

If an IB/3's SIO card is run at an aggregate rate greater than 84 Kbps
(for example, if two ports are run at 56 Kbps), the IB/3 will probably
not crash, but the serial links to the remote IB/3 will "bounce" up and
down, resulting in an unstable communication link and slowdown of data
throughput through the IB/3s.
