LAN Configuration and Management Manual

Introduction to the SLSA Subsystem

LAN Configuration and Management Manual—520469-012

2-5

ServerNet Architecture and SLSA

The ServerNet architecture on Integrity NonStop NS-series or NonStop S-series

servers allows up to 16 processors in a system to have direct access to a logical

interface (LIF). This feature allows you to load-balance your data communications with

greater ease. For example, you can run Transmission Control Protocol/Internet

Protocol (TCP/IP) stacks in multiple processors with access to the same LIF.

Before G05, the TCP/IP process needed to be in the processor that had ownership of

the ServerNet addressable controller (SAC). Starting with G05, the SAC ownership

concept has changed; the owning process retains responsibility for downloading

operational code and for reporting errors but no longer has the exclusive data path to

the SAC. Starting with G06, TCP/IP has been modified to take advantage of this new

functionality in SLSA.

ServerNet architecture and NonStop systems allow you to run a single IP address

(provided by Parallel Library TCP/IP and NonStop TCP/IPv6) or multiple IP addresses

(provided by multiple TCP/IP processes balanced between multiple processors) over

multiple processors that access the same LIF. With Integrity NonStop NS-series and

NonStop S-series servers, there is a one-to-many relationship between LIFs and

processors.

By contrast, on NonStop K-series servers, multiple IP addresses running in multiple

processors require multiple communications controllers (the K-series equivalent of

adapters.) There is a one-to-one relationship between communications controllers and

processors when supporting multiple IP addresses.

Figure 2-2 on page 2-6 and Figure 2-3 on page 2-7 show examples of an application

and a Domain Name Server (DNS) taking advantage of the multiple processor LIF

access feature.

In Figure 2-2, the DNS entry has multiple IP addresses for a given name and those

addresses can be in different processors supported by a single LIF.

In Figure 2-3, the DNS entry has a single IP address for a given name and the address

applies to all processors running Parallel Library TCP/IP or NonStop TCP/IPv6 on a

given LIF.

Note. J-Series RVUs and NonStop BladeSystems have different architecture and networking

considerations. For more information, see the HP NonStop Networking Overview.

Note. Parallel Library TCP/IP is not supported on Integrity NonStop NS-series servers.