Lexmark IBM 9077 - Manual (Page 24)

6 IBM 9077 SP Switch Router: Get Connected to the SP Switch
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
SP
Switch
Processor
Nodes
SP System
IBM 9570 Disk
Array
Subsystem
ATM
Switch
SP Switch
Adapter
SP Switch
Adapter
HIPPI
Adapter
ATM
OC-12c
4-port
FDDI
HIPPI
Adapter
ATM
OC-3c
8-port
E-net 10/100
SP Switch
Adapter
SP Switch
Router