Lexmark IBM 9077 - Manual (Page 30)

12 IBM 9077 SP Switch Router: Get Connected to the SP Switch
The second case has proven to be very expensive as well. The RS/6000 SP
node was not designed for routing. It is not a cost-effective way to route traffic
for the following reasons:
• It takes many CPU cycles to process routing. The CPU is not a dedicated
router and is very inefficient when used to route IP traffic (this processing
can result in usage of up to 90%).
• It takes a lot of memory to store route tables. The memory on the RS/6000
SP node is typically more expensive than router memory.
The CPU on a node can only drive the system I/O bus at less than 80
megabytes per second, which is less than what a high-end router can do.
For these reasons, the performance of routers in handling IP traffic from
remote systems to the RS/6000 SP nodes was limited.
2.1.5 Routing with the GRF
The GRF is a dedicated, high-performance router (see Figure 6). Each SP
Switch Router adapter can route up to 30,000 packets per second and up to
100 MB/s into the SP Switch network in each direction simultaneously.
Figure 6. Routing with GRF
SP Switch
Node
Node
Node
GRF
. .
.
FDDI
ATM
Ethernet
Internet/Intranet