Chapter 10 Redundancy; Vrrp - Avaya P333R-LB User Manual

Chapter 10
Redundancy
This chapter discusses the redundancy schemes of VRRP, SRRP, and additional
redundancy schemes (Real Server Group Backup and Real Server Backup).

VRRP

VRRP is an IETF protocol designed to support redundancy of routers on the LAN,
as well as load balancing of traffic. VRRP is transparent to host stations, making it
an ideal choice when redundancy, load balancing and ease of configuration are all
required.
The concept underlying VRRP is that a router can backup other routers, in addition
to performing its primary routing functions. Redundancy is achieved by
introducing the concept of a virtual router. A virtual router is a routing entity
associated with multiple physical routers. The routing functions of the virtual router
are performed by one of the physical routers with which it is associated. This router
is known as the master router.
For each virtual router, VRRP selects a master router. If the selected master router
fails, another router is selected as master router.
In VRRP, two or more physical routers can be associated with a virtual router, thus
achieving the extreme reliability inherent in the P333R-LB SAFER architecture.
In a VRRP environment, host stations interact with the virtual router. They are not
aware that this router is a virtual router, and they are not affected when a new
router takes over the role of master router. This makes VRRP fully interoperable
with every host station.
VRRP can be activated on an interface using a single command, while allowing for
the necessary fine-tuning of the many VRRP parameters. For a detailed description
of VRRP, refer to VRRP standards and published literature.
Introducing a Load Balancer into the network creates a single point of failure. As a
result, users will most likely want a backup implementation between two
P333R-LBs.
For FWLB, the my-ip parameter of the hc-ip command can also be an associated
IP address of a virtual router. In addition, the override addr owner parameter
of the ip vrrp command should be used.
For AR, at least two virtual routers should be configured: one for the client vlan area
and the other for the server vlan area. The servers should be configured with the
VRRP IP as their default gateway. In addition, the clients should be configured with
the VRRP IP as their default gateway. The same physical router should be the
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