Expand Configuration and Management Manual (G06.24+)

Tuning
Expand Configuration and Management Manual—523347-008
20-19
Multi-CPU Paths
\A and \B are connected with a superpath, \C is connected to \B, and \D connects to
\C.
In reference to \A, \B is a neighbor and \C and \D are non-neighbors. When \A makes a
connection to \C, the load is not distributed over different paths, but only one path is
used for all traffic to \C.
In order to make sure that the correct path is used, \B records which line handler is
used for \A's connection to \C. This is done by setting an entry in the reverse pairing
table so \B knows which line handler to send the packets from \C to \A.
The reverse pairing table on \B can be displayed with the SCF command:
-> INFO PROCESS $NCP, RPT \A
This displays which line handlers \B and \A are using for the connections which \A has
that go through \B.
When \A makes a connection to \D, a different line handler might be selected as the
one to carry the traffic from \A to \D. This way, the load to different non-neighbors can
be distributed among the different paths in the superpath. However, the traffic to a
single non-neighbor only uses one of the paths in the superpath.
Figure 20-4. Pair Count Balancing for Neighbors and Non-Neighbors
CPU 0
CPU 1
CPU 2
CPU 3
CPU 0
CPU 1
CPU 2
CPU 3
\A \B
\C \D
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