HP 6125XLG R2306-HP 6125XLG Blade Switch High Availability Configuration Guide - Page 45

Configuring VRRP, Overview

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Configuring VRRP The interfaces that VRRP involves can be only Layer 3 Ethernet interfaces and VLAN interfaces unless otherwise specified. You can configure an Ethernet port as a Layer 3 interface by using the port link-mode route command (see Layer 2-LAN Switching Configuration Guide). Overview Typically, you can configure a default gateway for every host on a LAN. All packets destined for other networks are sent through the default gateway. As shown in Figure 12, when the default gateway fails, no hosts can communicate with external networks. Figure 12 LAN networking Using a default gateway facilitates your configuration but requires high availability. Using more egress gateways improves link availability but introduces the problem of routing among the egresses. Virtual Router Redundancy Protocol (VRRP) is designed to address this issue. VRRP adds a group of network gateways to a VRRP group called a "virtual router." A VRRP group comprises one master and multiple backups, but has only one virtual IP address. The hosts on the subnet only need to configure this virtual IP address as their default network gateway for communicating with external networks. The virtual IP address of the virtual router can be either an unused IP address on the subnet where the VRRP group resides or the IP address of an interface on a router in the VRRP group. In the latter case, the router is called the IP address owner. A VRRP group can have only one IP address owner. VRRP avoids single points of failure and simplifies the configuration on hosts. When the master in the VRRP group on a multicast or broadcast LAN (for example, an Ethernet network) fails, another router in the VRRP group can take over as the master without causing dynamic route recalculation, route re-discovery, gateway reconfiguration on the hosts, or traffic interruption. VRRP operates in either of the following modes: • Standard mode-Implemented based on RFCs. For more information, see "VRRP standard mode." 40

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40
Configuring VRRP
The interfaces that VRRP involves can be only Layer 3 Ethernet interfaces and VLAN interfaces unless
otherwise specified. You can configure an Ethernet port as a Layer 3 interface by using the
port
link-mode
route
command (see
Layer 2—LAN Switching Configuration Guide
).
Overview
Typically, you can configure a default gateway for every host on a LAN. All packets destined for other
networks are sent through the default gateway. As shown in
Figure 12
, when the default gateway fails,
no hosts can communicate with external networks.
Figure 12
LAN networking
Using a default gateway facilitates your configuration but requires high availability. Using more egress
gateways improves link availability but introduces the problem of routing among the egresses.
Virtual Router Redundancy Protocol (VRRP) is designed to address this issue. VRRP adds a group of
network gateways to a VRRP group called a "virtual router." A VRRP group comprises one master and
multiple backups, but has only one virtual IP address. The hosts on the subnet only need to configure this
virtual IP address as their default network gateway for communicating with external networks.
The virtual IP address of the virtual router can be either an unused IP address on the subnet where the
VRRP group resides or the IP address of an interface on a router in the VRRP group. In the latter case, the
router is called the IP address owner. A VRRP group can have only one IP address owner.
VRRP avoids single points of failure and simplifies the configuration on hosts. When the master in the
VRRP group on a multicast or broadcast LAN (for example, an Ethernet network) fails, another router in
the VRRP group can take over as the master without causing dynamic route recalculation, route
re-discovery, gateway reconfiguration on the hosts, or traffic interruption.
VRRP operates in either of the following modes:
•
Standard mode
—Implemented based on RFCs. For more information, see "
VRRP standard mode
."