IBM 9077 manual Routing with the GRF, Routing with GRF

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.

Node		Internet/Intranet
Node
. . .
SP Switch
Node		ATM
	GRF	FDDI
		Ethernet

Figure 6. Routing with GRF

12IBM 9077 SP Switch Router: Get Connected to the SP Switch