High Availability Features For Ex Series Switches Overview - Juniper JUNOS OS 10.3 - SOFTWARE Manual

Complete Software Guide for Junos

High Availability Features for EX Series Switches Overview

VRRP
Graceful Protocol Restart
20
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OS for EX Series Ethernet Switches, Release 10.3
Understanding Storm Control on EX Series Switches on page 2791
Understanding the Use of Policers in Firewall Filters on page 3036
High availability refers to the hardware and software components that provide redundancy
and reliability for packet-based communications. This topic covers the following high
availability features of Juniper Networks EX Series Ethernet Switches:
VRRP on page 20
Graceful Protocol Restart on page 20
Redundant Routing Engines on page 21
Graceful Routing Engine Switchover on page 21
Virtual Chassis Software Upgrade and Failover Features on page 22
Link Aggregation on page 22
You can configure the Virtual Router Redundancy Protocol (VRRP) or VRRP for IPv6 on
Gigabit Ethernet interfaces, 10-Gigabit Ethernet interfaces, and logical interfaces on EX
Series switches. When VRRP is configured, the switches act as virtual routing platforms.
VRRP enables hosts on a LAN to make use of redundant routing platforms on that LAN
without requiring more than the static configuration of a single default route on the hosts.
The VRRP routing platforms share the IP address corresponding to the default route
configured on the hosts. At any time, one of the VRRP routing platforms is the master
(active) and the others are backups. If the master routing platform fails, one of the backup
routing platforms becomes the new master, providing a virtual default routing platform
and enabling traffic on the LAN to be routed without relying on a single routing platform.
Using VRRP, a backup EX Series switch can take over a failed default switch within a few
seconds. This is done with minimum loss of VRRP traffic and without any interaction
with the hosts.
For more information on VRRP, see "Understanding VRRP on EX Series Switches" on
page 1671.
With standard implementations of routing protocols, any service interruption requires
an affected switch to recalculate adjacencies with neighboring switches, restore routing
table entries, and update other protocol-specific information. An unprotected restart of
a switch can result in forwarding delays, route flapping, wait times stemming from protocol
reconvergence, and even dropped packets. Graceful protocol restart allows a restarting
switch and its neighbors to continue forwarding packets without disrupting network
performance. Because neighboring switches assist in the restart (these neighbors are
called helper switches), the restarting switch can quickly resume full operation without
recalculating algorithms from scratch.
Copyright © 2010, Juniper Networks, Inc.