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JUNOSe 11.1.x Service Availability Configuration Guide
Figure 6: VRRP Configuration Without the Real Address Owner
Assuming that preemption is enabled, the router that is configured with the highest
priority for each VRID becomes the master router. If priorities are the same, the
router that has the highest primary address becomes the master router.
This configuration shows how the address owner does not necessarily need to exist
under VRRP, and all PCs can reach destinations outside of their network through the
current master VRRP router. Depending on the accept-data configuration, the PCs
may even be able to ping their default gateway.
The election protocol specified in VRRP uses IP multicast packets to provide the
router with redundancy. Therefore, VRRP can operate over a variety of multiaccess
LAN technologies that support IP multicast. It is important to remember that there
is always one master router for an IP address shared by the redundancy group.
How VRRP Is Implemented in E Series Routers
VRRP is implemented in E Series routers to meet two goals. The first goal is to avoid
the single point of failure inherent to hosts that have a single default gateway
configured. The second goal is to keep the complexity of redundancy away from the
hosts themselves. These goals comply with RFC 3768 and RFC 2787.
The association between VRIDs and IP addresses is coordinated among all
participating VRRP routers. The following scenario can help you understand how
VRRP is implemented in the router.
1.
2.
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How VRRP Is Implemented in E Series Routers
An E Series router assigns common VRIDs to the group of routers that are going
to share IP addresses.
The E Series router sends VRRP advertisements to well-known multicast
addresses. The router that owns the addresses automatically becomes the master
and sends periodic VRRP advertisement messages. A VRRP advertisement
consists of the IP addresses that the master router controls and the VRID.
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