Nortel SMC 2450, Руководство по внедрению

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Page 180 of 260 Maintenance
553-3001-225 Standard 1.00 May 2006
Gratuitous ARP (GARP)
After the backup detects a failure in the active master, the backup
immediately flashes a Gratuitous ARP (GARP) message to the end-hosts on
the virtual router interface.
The GARP, an unsolicited ARP response, forces end-hosts to update their
ARP caches with the new MAC address and IP address mapping. Then the
backup delays a period of time defined by the GARP delay value before
sending continuous GARP messages at intervals defined by the Gratuitous
Broadcast value. The GARP message shortens the time it takes an SMC to
discover a lost backup. Continuous GARP messages prevent end-hosts from
aging out their ARP entries for the virtual router.
Increasing the Gratuitous Broadcast value cuts down on the GARP traffic, but
lengthens the interval between end-host ARP cache updates.
VRRP interface
Define the Virtual router interface parameters per virtual router at the VRRP
Interface Menu. Before you configure the virtual router interface parameters,
you must first configure the interface IP parameters at the Interface Menu.
Each virtual router interface requires the following parameters:
• a common virtual router IP address
• a common virtual router ID (vrid)
• two subaddresses (one representing each SMC host)
• a common port on each SMC
Real router IP addresses
The real router IP addresses are assigned to the physical SMC.
The IP addresses (ip1 and ip2) you enter at the Interface Menu become the
real router IP addresses. You can also enter other real interface parameters,
including the port.