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The network topology is specified during the installation. A topology specifier is set up in the
cluster database. In the cluster DB site table, topology=<specifier>. Table 1-4 shows the
supported four-drawer and single-drawer Supernode topologies.
Table 1-4 Supported four-drawer and single-drawer Supernode topologies
Topology
256D
128D
64D
32D
16D
8D
4D
2D
1D
2D_SDSN
8D_SDSN
ISR network routes
Each ISR includes a set of hardware route tables. The Local Network Management Controller
(LNMC) routing code generates and maintains the routes with help from Central Network
Manage (CNM), as shown in Figure 1-26 on page 38. These route tables are set up during
system initialization and are dynamically adjusted as links go down or come up during
operation. Packets are injected into the network with a destination identifier and the route
mode. The route information is picked up from the route tables along the route path that is
based on this information. Packets that is injected into the interconnect by the HFI employ
source route tables with the route partially determined. Per-port route tables are used to route
packets along each hop in the network. Separate route tables are used for intersupernode
and intrasupernode routes.
Routes are classified as
two compute nodes in a system. There are multiple direct routes between a set of compute
nodes because a pair of supernodes are connected by more than one D-link.
The network topology features two levels and therefore the longest direct route has three
hops (no more than two L hops and at most one D hop). This configuration is called an L-D-L
route.
The following conditions exist when source and destination hubs are within a drawer:
The route is one L-hop (assuming all of the links are good).
LNMC needs to know only the local link status in this CEC.
Maximum number of supernodes
Single-Drawer Supernode topologies
direct
indirect
or
. A direct route uses the shortest path between any
Chapter 1. Understanding the IBM Power Systems 775 Cluster
3
5
8
16
32
64
128
256
512
48
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