IBM RS/6000 SP, Problem Determination Manual

Page: 108 / 316

This soft copy for use by IBM employees only.
Figure 41. The HiPS Showing the External Connections
It is worth stating at this point that the Control Workstation is not part of the
switch network, and putting a switch adapter in the Control Workstation is not
supported in the current environment.
Setting aside the LC8 Switch for the time being, there are 2 main types of switch
boards that can be used:
•
Node switch boards
•
Intermediate switch boards
To explain why intermediate switch boards are required, it is necessary to return
to the comment made earlier that 16
jack connections are available for
communication with other switches. If you take the situation where there are 2
switches in the network, all 16 of these are available to connect to the other
switch (despite the fact that data will only flow down 8 of these). If there are 3
switches, then 8 cables will go to the first switch and 8 to the other.
The number of cables going to each switch decreases to the point where you
have 5 switches allowing only 4 cables to go to each switch. Having more than 5
switches in a configuration is not currently supported (although there is no
intrinsic reason why it cannot be done) because by having less than 4 cables to
connect each switch, the bandwidth of the network starts to be compromised.
The intermediate switch boards remedy this situation. Special frames that
contain only switches and their associated cables are required to house these
boards. These switch boards only communicate with other switches for which
there are all 32 jack connections available. Within these switch frames there are
always 4 intermediate switch boards, all of which are cabled to the node switch
boards for configurations up to the 128-way size. The 4 switch boards, with 32
connections each, make 128 connections possible.
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SP PD Guide