CANOGA PERKINS CanogaOS Configuration Guide - Manual (Page 154)

CanogaOS Configuration Guide
Proprietary & Confidential Canoga Perkins Metro Ethernet Switches Page 154 of 350
method is that it produces a single point of failure if this first hop router fails.
The Virtual Router Redundancy Protocol attempts to solve this problem by introducing the
concept of a virtual router, composed of two or more VRRP routers on the same subnet. The
concept of a virtual IP address is also introduced, which is the address that end hosts configure as
their default gateway. Only one of the routers (called the Master) forwards packets on behalf of
this IP address. In the event that the Master router fails, one of the other routers (Backup)
assumes forwarding responsibility for it.
At first glance, the configuration outlined in might not seem very useful, as it doubles the cost
and leaves one router idle at all times. This, however, can be avoided by creating two virtual
routers and splitting the traffic between them.
20.1.4 Limitations
• The VRRP RFC specifies that the master-down-timer is a fraction that is always <1. The Linux
operating system supports only timers that are multiples of 1 second. This might result in
increasing the length of time the system takes in stabilizing the master, after master fails in the
network with multiple backups.
• MD5 authentication is not yet supported for VRRP.