Managing Serviceguard 12th Edition, March 2006

Understanding Serviceguard Software Components
How the Network Manager Works
Chapter 3104
— Each primary interface should have at least one standby
interface, and it should be connected to a standby switch.
— The primary switch should be directly connected to its standby.
— There should be no single point of failure anywhere on all
bridged nets.
Local Switching
A local network switch involves the detection of a local network interface
failure and a failover to the local backup LAN card (also known as the
Standby LAN card). The backup LAN card must not have any IP
addresses configured.
In the case of local network switch, TCP/IP connections are not lost for
Ethernet, but IEEE 802.3 connections will be lost. For IPv4, Ethernet,
Token Ring and FDDI use the ARP protocol, and HP-UX sends out an
unsolicited ARP to notify remote systems of address mapping between
MAC (link level) addresses and IP level addresses. IEEE 802.3 does not
have the
rearp function.
IPv6 uses the Neighbor Discovery Protocol (NDP) instead of ARP. The
NDP protocol is used by hosts and routers to do the following:
• determine the link-layer addresses of neighbors on the same link,
and quickly purge cached values that become invalid.
• find neighboring routers willing to forward packets on their behalf.
• actively keep track of which neighbors are reachable, and which are
not, and detect changed link-layer addresses.
• search for alternate functioning routers when the path to a router
fails.
Within the Ethernet family, local switching configuration is supported:
• 1000Base-SX and 1000Base-T
• 1000Base-T or 1000BaseSX and 100Base-T
On HP-UX 11i, however, Jumbo Frames can only be used when the
1000Base-T or 1000Base-SX cards are configured. The 100Base-T and
10Base-T do not support Jumbo Frames. Additionally, network interface
cards running 1000Base-T or 1000Base-SX cannot do local failover to
10BaseT.