Reference Guide

Virtual Router Redundancy Protocol (VRRP) | 949
VRRP Benefits
With VRRP configured on a network, end-station connectivity to the network is not subject to a single
point-of-failure. End-station connections to the network are redundant and they are not dependent on IGP
protocols to converge or update routing tables.
VRRP Implementation
E-Series supports an unlimited total number of VRRP groups on the router while supporting up to 255
VRRP groups on a single interface (Table 50-1).
C-Series supports a total of 128 VRRP groups on the switch with varying number of maximum VRRP
groups per interface (Table 50-1).
S-Series supports a total of 120 VRRP groups on a switch with FTOS or a total of 20 VRRP groups when
using SFTOS. The S-Series supports varying number of maximum VRRP groups per interface
(Table 50-1).
Z-Series supports a total of 255 VRRP groups on a switch. The total number of VRRP groups per system
should be less than 512.
Within a single VRRP group, up to 12 virtual IP addresses are supported. Virtual IP addresses can belong
to the primary or secondary IP address’ subnet configured on the interface. You can ping all the virtual IP
addresses configured on the Master VRRP router from anywhere in the local subnet.
Though FTOS on E-Series supports unlimited VRRP groups, default VRRP settings may affect the
maximum number of groups that can be configured and work efficiently, as a result of hardware throttling
VRRP advertisement packets reaching the RP2 processor on the E-Series, the CP on the C-Series, or the
FP on the S-Series. To avoid throttling VRRP advertisement packets, Dell Force10 recommends you to
increase the VRRP advertisement interval to a value higher than the default value of 1 second. The
recommendations are as follows:
Note: The Layer 2 CAM is limited to 512 Local Destination Addresses, which limits the number of VRRP
groups that can be supported. This number may be further reduced depending on the number of Layer 3
VLANs configured in the system as the Layer 3 VLANs also use Local Destination Addresses.
Table 50-1. Recommended VRRP Advertise Intervals
Total VRRP Groups
Recommended Advertise Interval Groups/Interface
E-Series C-Series S-Series Z-Series
E-Series
ExaScale
E-Series
TeraScale C-Series S-Series Z-Series
Less than 250 1 second 1 second 1 second 1 second 512 255 12 12 12
Between 250 and 450 2 seconds 2 - 3 seconds 2 - 3 seconds 2 - 3
seconds
512 255 24 24 24