The method for wiring the administration network and interconnect networks allows expansion of the system within the system's initial interconnect fabric without recabling of any existing nodes. If additional switch chassis or ports are added to the system as part of the expansion, some recabling may be necessary.

3.4.1 QsNet Interconnect Connections

For the QsNetII interconnect developed by Quadrics, it is important that nodes are connected to the Quadrics switch ports in a specific order. The order is affected by the order of the administration network and console network.

Because the Quadrics port numbers start numbering at 0, the highest port number on the Quadrics switch is port max-nodeminus 1, where max-nodeis the maximum number of nodes possible in the system. This is the port on the Quadrics switch to which the head node must be connected.

The head node in an HP XC system is always the node connected to the highest port number of any node on the Root Administration Switch and the Root Console Switch.

NOTE: The head node port is not the highest port number on the Root Administration Switch. Other higher port numbers are used to connect to other switches. If the Root Administration Switch is a ProCurve 2848 switch, the head node is connected to port number 42, as discussed in “Root Administration Switch” (page 50).

If the Root Administration Switch is a ProCurve 2824 switch, the head node is connected to port number 22 on that switch, as discussed in “Root Administration Switch” (page 50). The head node should, however, be connected to the highest port number on the interconnect switch.

The next node connected directly to the root switches (Administration and Console) should have connections to the Quadrics switch at the next highest port number on the Quadrics switch (max-nodeminus 2). All nodes connected to the Root Administration Switch will be connected to the next port in descending order.

Nodes attached to branch switches must be connected starting at the opposite end of the Quadrics switch. The node attached to the first port of the first Branch Administration Switch should be attached to the first port on the Quadrics switch (Port 0).

3.4.2 Gigabit Ethernet Interconnect Connections

The HP XC System Software is not concerned with the topology of the Gigabit Ethernet interconnect, but it makes sense to structure it in parallel with the administration network in order to make your connections easy to maintain.

Because the first logical Gigabit Ethernet port on each node is always used for connectivity to the administration network, there must be a second Gigabit Ethernet port on each node if you are using Gigabit Ethernet as the interconnect.

Depending upon the hardware model, the port can be built-in or can be an installed card. Any node with an external interface must also have a third Ethernet connection of any kind to communicate with external networks.

3.4.3 Administration Network Interconnect Connections

In cases where an additional Gigabit Ethernet port or switch may not be available, the HP XC System Software allows the interconnect to be configured on the administration network. When the interconnect is configured on the administration network, only a single LAN is used.

However, be aware that configuring the system in this way may negatively impact system performance.

To configure the interconnect on the administration network, you include the --ic=AdminNetoption on the discover command line, which is documented in the HP XC System Software Installation Guide.

3.4 Interconnect Connections

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