HP AB500A - Integrated Lights-Out Advanced Technology Brief page 6

Selected servers offer a Shared Network Port (SNP) that allows network access to both iLO and the
host server through a single network port (see Figure 2), rather than dedicating a second port to the
management processor. An SNP allows HP ProLiant servers to deliver optimal performance with fewer
required ports, which can reduce recurring port use costs. With the SNP, iLO network traffic can be
routed through a sideband connection on one of the NIC interfaces. Although the iLO traffic shares a
port with the server OS traffic, both iLO and the server NIC have their own Media Access Control
(MAC) address. Having separate MAC addresses lets iLO and the server have separate Internet
Protocol (IP) addresses. For increased security and network consolidation, administrators can use
optional virtual LAN (vLAN) tagging with manageable network switches to segregate iLO and host
traffic, creating separate logical networks for host and management traffic. Using the SNP also
simplifies hardware installation and reduces overall hardware costs because both corporate and iLO
network traffic comes through the system NIC.
Figure 2. These diagrams illustrate three possible port configurations for system management traffic.
The iLO processor provides logic functions that monitor and control the host server. This logic
implements Automatic Server Recovery-2 (ASR-2), which reboots the server automatically after
recoverable faults and before imminent failures. Additional monitoring and control capabilities have
expanded over time. For servers that support system-embedded health monitoring, the iLO 2 processor
can monitor fans, power supplies, and temperatures. Server documentation for specific servers
provides sensor and temperature information available through the Lights-Out processor.
The host firewall and bridge logic let the embedded processor control the flow of information between
the host server and the management console. It protects against unauthorized access through the
system PCI interface, and it shields sensitive information that may be stored in the memory or
firmware. For additional information about host firewall and bridge logic, refer to the "HP Integrated
Lights-Out security" technology brief at this URL:
http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c00212796/c00212796.pdf.
Essentially, host power and fault isolation logic split the management processor into two separate
areas: one operating under normal host system power; the other connected to the auxiliary power
plane of the server. Even when the host server is powered down, the iLO processor will continue to
operate, although the portions of iLO that communicate with the host processor are isolated. If the
host server has redundant power supplies, power redundancy protects both the iLO processor and the
host processor if a power supply fails.
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