IBM RS/6000 SP Handbook page 158

Note: With F/C 9122 RS/6000 Server Attached Node and F/C 9123 RS/6000
Server Frame Attachement, two 15 m (49 ft.) RS/232 cables and a
frame-to-frame electrical ground cable are provided. So, on a switched
Clustered Enterprise Server environment, you may not need to order the F/C
3150 and F/C 3151 serial cables to connect the Clustered Enterprise Server
to CWS. The frame-to-frame ground maintains the 9076-555 and the
Clustered Enterprise Server at the same electrical potential.
The SP Attachment Adapter uses an SP Switch cable to connect to an available
switch port on a 9076-555 Stand-alone SP Switch.
Note: You must order one of the following cables, which connect the adapter
to a valid switch port on the SP Switch:
10 m SP Switch/Switch or Switch/Node cable (F/C 9310)
20 m SP Switch to Switch cable (F/C 9320)
The cable must be ordered as part of the 9076-555 Stand-alone SP Switch.
There are some Clustered Enterprise Server placement limitations. Placement of
the Clustered Enterprise Server is limited by the length of its following supplied
cables:
1. The 10 m (33 ft.) frame-to-frame ground cable and RS/6000 SP System
Attachment adapter cable
2. The 15 m (49 ft.) RS-232 cables
Approximately 3 m (10 ft.) of cable is needed for the vertical portion of the cable
runs. Thus, the Clustered Enterprise Server must be no more than 7 m (23 ft.)
from the 9076-555 Stand-alone SP Switch (if it exists on your configuration) and
no more than 12 m (40 ft.) from the control workstation.
Note: Refer to Chapter 10, "Clustering configurations" on page 285 for more
details about the CES environment.
134 RS/6000 SP and Clustered IBM ^ pSeries Systems Handbook