Vrrp Tracking - Hirschmann MACH 4000 User Manual

VRRP/HiVRRP

5.2 VRRP tracking

By monitoring certain router statuses (e.g. line interruption), VRRP tracking
makes it possible to switch to a better router when a link goes down.
If there is a line interruption between switch S1 and router A
router B takes over the master function for virtual router 10.0.1.254.
Router A remains the master for virtual router 10.0.2.254. However, router A
no longer has a link to subnetwork 10.0.1.0.
The virtual router interfaces are independent of each other.
Default Gateway
10.0.1.254
10.0.1.20
Figure 17: Typical VRRP application
As soon as the VRRP master router with the VRRP tracking function active
detects the interruption of one of its links, it lowers its VRRP priority and in-
forms the other VRRP routers of this.
Then another VRRP router, which now has the highest VRRP priority due to
this change, can immediately take over the master function.
Solution without tracking:
Configure router A with a static route to router B or with a dynamic routing
procedure, so that router A finds a route into subnetwork 10.0.1.0.
50
S1
10.0.1.1
VR
10.0.1.254
10.0.1.2
5.2 VRRP tracking
Priority=200
A
VR
10.0.2.254
B
Priority=100
(see fig. 18),
Default Gateway
10.0.2.254
Routing L3P
Release 4.0 11/07