IBM 9570 Disk
Array
Subsystem
SP
Switch
Processor
Nodes
SP System
SP Switch | HIPPI |
Adapter | Adapter |
HIPPI
Adapter
| ATM |
|
| ATM | |
| ATM | Switch |
SP Switch |
| |
Adapter |
|
|
SP Switch
Adapter
FDDI
SP Switch
Router
Figure 1. SP Switch Router
The RS/6000 SP software treats this adapter as an extension node. It is a node because it takes up one port in the SP Switch and is assigned a node number. It is described as an extension because it is not a standard RS/6000 SP node, but an adapter card that extends the scope of the RS/6000 SP.
Although the term extension node represents the node appearance of the adapter, it does not define the connection. An extension node adapter is used for that purpose. Each extension node has an extension node adapter to represent its connection to the SP Switch.
2.1.1 Motivation
A thin node, which has a single microchannel, is unable to deliver more than about 30 MB/s to or from the SP Switch. Using a wide node, this number increases to 65 MB/s but is still unable to provide full bandwidth to even one HIPPI interface. It is also unable to feed 4 FDDI or 4 Ethernet 100BaseTx cards at full bandwidth.
A 135 MHz wide node’s CPU becomes saturated at about 5000 packets/second. A 10 Mb/s Ethernet uses a maximum of 1500 bytes for a
