Alcatel-Lucent OmniAccess 700, Руководство по настройке CLI

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Virtual Router Redundancy Protocol
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CLI Configuration Guide
Alcatel-Lucent
VRRP O
VERVIEW
VRRP eliminates the single point of failure inherent in the static default routed
environment. VRRP supplies a method of providing nonstop path redundancy and
gateway redundancy for an enterprise network by sharing protocol and Media
Access Control (MAC) addresses between redundant gateways. The protocol
consists of a virtual MAC address and a protocol address that are shared between
two or more gateway routers.
VRRP specifies an election protocol that dynamically assigns responsibility of a
virtual router to one of the VRRP routers on a LAN. The VRRP router controlling
the IP address(es) associated with the virtual router is called the Master. The
Master router provides default gateway functionality for hosts on the LAN. As the
default gateway, the master router forwards the packets received from the hosts
on the LAN or forwards packets received for the hosts on the LAN. The election
process provides forwarding responsibility to another VRRP router dynamically, if
the Master becomes unavailable. Any of the virtual router's IP addresses on a
LAN can then be used as the default first hop router by end-hosts. The advantage
gained from using VRRP is a higher availability default path without requiring
configuration of dynamic routing or router discovery protocols on every end-host.
During the startup, or through the use of the priority and preempt commands, one
of the routers is chosen to be the Active router (Master) and the second router is
designated as the standby (backup router). If the backup router fails to receive the
hello packet of the Master router, either the local LAN segment is unstable or the
Master router has had a failure. In either case the backup router assumes control
of the virtual MAC and the protocol addresses.
VRRP is intended for use with IPv4 routers only. VRRP packets are sent
encapsulated in IP packets.They are sent to the IPv4 multicast address assigned
to VRRP.
VRRP F
UNCTIONALITY
VRRP enables a group of routers to form a single virtual router to provide
redundancy. The LAN clients can then be configured with the virtual router as their
default gateway. The virtual router, representing a group of routers is also known
as a VRRP group.
VRRP I
NTERFACE
T
RACKING
The VRRP Interface Tracking feature extends the capabilities of the VRRP to
allow tracking of specific interfaces within the router that can alter the priority of a
router.
RFC
3768