Expand Configuration and Management Manual (G06.24+)

Tuning
Expand Configuration and Management Manual—523347-008
20-12
NAM Interface
For more information about Expand-over-NAM line-handler process configuration, refer
to Section 10, Configuring Expand-Over-X.25 Lines and Section 14, Configuring Multi-
Line Paths.
Expand-Over-IP Configuration
Expand-over-IP line-handler processes use a NonStop TCP/IP process to provide
TCP/IP connectivity. The NonStop TCP/IP process associated with the Expand-over-IP
line-handler process must be configured in the same processor pair as the Expand-
over-IP line-handler process.
With Parallel Library TCP/IP and NonStop TCP/IPv6, the Expand line-handler process
must be configured in a processor where a TCPMON or TCP6MON process is running;
this usually yields a free choice of processor. It is not necessary nor beneficial in any
way to co-locate the Expand line-handler process and the TCPSAM or TCP6SAM
process.
For more information about Expand-over-IP line-handler process configuration, refer to
Section 8, Configuring Expand-Over-IP Lines.
NAM Interface
When a NAM interface is used, Layer 2 functions are managed by the NAM process,
thus reducing the load on the Expand line-handler process. Although the Expand line-
handler process has a potentially greater upper throughput limit when it uses a NAM
interface, overall system processor requirements are not reduced because some of the
workload is shifted to the NAM process. There is also an additional cost per packet for
the interprocess message between the Expand line-handler process and the NAM
process.
On a high-powered processor, such as a NonStop S-series server, this extra available
processor power can allow an Expand line-handler process to drive multiple high-
speed lines and greatly extend throughput.
The relationship between the size of the Expand packet and the NAM network native
packet size has a major influence on the available Expand line-handler process
bandwidth. Each Expand packet passed to the NAM is treated as a message by the
NAM.
If the NAM network native packet size is smaller than the Expand packet size, the NAM
process must fragment the Expand packet. If the Expand packet size is smaller than
the NAM packet size, the number of messages to the NAM will be higher than if the
Expand packet size were the same size as the NAM packet size.