HP 3500YL - Manual (Page 337)

Virtual Router Redundancy Protocol (VRRP)
General Operation
In figure 6-1:
1. Host “A” uses 10.10.100.1 as its next-hop gateway out of the subnet, as
represented by the virtual router (VR 1).
• Router 1 (the configured Owner) advertises itself as the Master in the
VR supporting the gateway and:
–
“owns” the VR’s (virtual) IP address
– transmits ARP responses that associate the VR’s virtual IP
address with the (shared) source MAC address for VR 1.
• During normal operation, Router 1 forwards the routed traffic for host
“A”.
2. If Router 1 fails or otherwise becomes unavailable:
a. Router 1 advertisements of its Master status for VR 1 fail to reach
Router 2 (which is the only configured backup).
b. After the time-out period for receiving Master advertisements expires
on Router 2, the VR initiates a failover to Router 2 and it becomes the
new Master of the VR.
c. Router 2 advertises itself as the Master of the VR supporting the
gateway and:
–
takes control of the VR’s (virtual) IP address
– begins transmitting ARP responses that associate the VR’s virtual
IP address with the (shared) source MAC address for VR 1
d. Host “A” routed traffic then moves through Router 2.
3. If Router 1 again becomes available:
a. Router 1 resumes advertising itself as the Master for the VR and sends
ARP responses that associate the VR’s virtual IP address with the
(shared) source MAC address for VR 1.
b. Router 2 receives the advertisement from Router 1 and ceases to
operate as the VR’s Master, and halts further transmission of its own
VRRP advertisements and ARP responses related to VR 1.
c. The VR executes a failback to Router 1 as Master, and Host “A” traffic
again moves through Router 1.
6-7