Layer 3 Features; Modes Of Operation; Forwarding; Redundancy - Avaya P334T-ML User Manual

Chapter 1 Overview

Layer 3 Features

Modes of Operation

The P334T-ML has two modes of operation (in each mode, Layer 2 is always active):
• Layer 2-only mode
• Router mode and Layer 2.
Note: This section is only applicable if you either purchased a preconfigured
P334T-ML or purchased a Routing License Key Certificate and activated the License
Key

Forwarding

The P334T-ML forwards IP packets between IP networks. When it receives an IP
packet through one of its interfaces, it forwards the packet through one of its
interfaces. P334T-ML supports multinetting, enabling it to forward packets between
IP subnets on the same VLAN as well as between different VLANs. Forwarding is
performed through standard means in Router mode.

Redundancy

Routing protocols naturally provide some level of redundancy. However, IP
stations that are manually configured with a single 'default gateway' IP address do
not naturally recover when their default gateway fails. These stations do not
automatically try to use other routers or Layer-3-switches connected to the same
subnet.
The P334T-ML supports two router redundancy protocols, VRRP and SRRP, to
solve this problem.

Virtual Router Redundancy Protocol (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. This 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.
8 P334T-ML User's Guide