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Multiple RS/6000 SPs and Multiple GRFs 227
Performance:
To get a rough overview of the data transfer rates that can be achieved in this
scenario, the following test was performed:
1. We used
ftp to conduct several file transfers of a 300 MB file from the
nodes in SP2 to one chosen node in SP21, and at the same time used ftp
to conduct several file transfers of a 300 MB file from the nodes in SP21 to
a chosen node in SP2. We sent the files to /dev/null on the receiving node
to eliminate any hard disk influence.
We saw up to about 44.5 MB/s with just one side sending data. With all
nodes sending and receiving, we achieved a duplex throughput of about
64 MB/s on the ATM port.
Although this is far from the theoretical maximum throughput an ATM
OC-12c adapter can provide, it turns out that a 622 Mb/s link between two
SP Switch Routers will be a viable solution.
7.3 HIPPI Backbone Connection
With a nominal speed of 100 MB/s duplex, connecting two GRFs with HIPPI
media cards seems the fastest choice. But then, HIPPI cables are limited to a
length of 25m (Ascend provides and guarantees 50m cables).
Below are the steps to set up the HIPPI backbone connection with two GRF
routers.
Configuration assumptions:
• The SP Switch Router HIPPI media card has been installed according to
Section 4.5, “HIPPI Configuration” on page 133 on both GRF routers, and
works properly.
• The SP Switch Router Adapter card has been installed according to
Section 3.7, “Step-by-Step Media Card Configuration” on page 86 on both
GRF routers, and works properly.
• The SP Switch Router Adapter card and SP processor node Switch
adapters are in the same IP subnet on the respective SP.
• ARP should be enabled on the SP Switch network to provide the most
flexibility in assigning IP addresses (strongly recommended!).
• If ARP is disabled on the SP Switch network, the IP addresses assigned to
the nodes must be determined by the switch node numbers.
Note:
The SP Switch Router Adapter card will not properly forward IP data to
nodes assigned with an IP address that is in another subnet.