IBM RS/6000 SP Handbook page 378

frame can be assigned the frame number 1. In this case, the enterprise servers
can be SP-attached to the SP with switch port number 0 and 1, as long as slot 0
and 1 are available. However, in this way, reconfiguration of the CES numbering
is required and if in a large scale CES (up to 32 nodes), the reconfiguration may
require lots of effort. The reconfiguration is shown in Figure 10-18.
Frame no. =2
Switch port no. = 0
Figure 10-18 Reconfigure the CES numbers to fit into an SP
Another way to solve the problem is to add an SP switch. If you have an SP
switch, you can add the enterprise servers to use any available switch port
numbers available in the SP switch regardless to the frame numbers.
Therefore, you can see an appropriate numbering in a CES can prevent potential
problems in future planning.
For CES numbering, there are also some recommendations provided here to
provide greater flexibility:
1. For a CES system with 16 or less enterprise servers, start the frame number
larger than 1. For a CES system with 17-32 nodes, start the frame number
larger than 2.
As described previously, if you have a 16-node CES system, you should start
the frame number with at least 2. This helps avoid the switch port numbering
problem (described above) when you add an switchless SP frame in the
future. Since a switch frame can provide up to 16 switch port numbers, you
have to install a second switch frame if you have more than 16 enterprise
servers. In this case, it may be better to skip the frame number 2 also when
assigning frame numbers to the CES from the beginning. Sometimes, if SP
nodes are installed in the SP frame, the starting frame number for CES may
be larger than 2.
354 RS/6000 SP and Clustered IBM ^ pSeries Systems Handbook
CES system
Frame no. =3
Switch port no. = 1
Add a switchless
SP frame
Frame no. = 1
(Switch port numbers: 0-15)
14 15
12 13
10 11
8 9
6 7
4 5
2 3
0 1