Product guide

Router Redundancy Using XRRP
Overview of XRRP Operation
Standard Fail-Over. In the multiple-VLAN situation in which all communi-
cation between the routers in the Protection Domain is lost, the standard
XRRP fail-over occurs. As shown in figure 6, Router-2 has lost communica-
tions on all of its XRRP virtual router interfaces. In this case, Router-1 will no
longer hear XRRP packets coming from Router-2. If that condition persists for
3 advertisement intervals, Router-1 then takes over all of the virtual routers
from Router-2.
Figure 12-5.Standard XRRP Fail-Over with Total VLAN Failure
If the cause of the total VLAN access failure, as shown in figure 17-5, is because
of a complete router failure (due to building power loss, for example), the
router that remains active will wait for the three XRRP advertisement intervals
and will then take control of the failed router’s IP and MAC addresses. If both
routers are still active but all network connections between them have been
severed, then both routers will take over for each other. This means that
identical IP and MAC addresses will exist on both routers, but in a completely
severed network, there will be no duplicated MAC or duplicate IP address
errors.
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