HP 6400cl, Management Manual, Page: 582 / 664

Router Redundancy Using XRRP
Overview of XRRP Operation
■ Router connectivity – In general peer routers using XRRP must have
identical connectivity. That is, they must have the same access to all
remote subnets, and the route costs of the access must be the same. This
will prevent the routing protocols from using the peer XRRP router as the
best path to get to a given subnet.
If this is not done, then fail-over may have to wait until the routing
protocols converge before full connectivity is restored. Should one router
have exclusive access to a given subnet, (that is, the only way one of the
XRRP routers can get to a given subnet is though its peer) connectivity to
those exclusive subnets may be lost when fail-over occurs.
■ SNMP Requests – SNMP requests on an XRRP router interface follow
the virtual interface, which may be different from the physical interface
in a fail-over situation. Alternately, you can ensure that the SNMP requests
are made on the management VLAN or other non-XRRP interface.
■ Multiple VLAN Considerations – When using multiple VLANs, some
consideration must be given to whether the router interfaces are
connected to devices that have a
multiple forwarding database (a MAC
address table for each VLAN):
• If the switch at the other end of a router interface connection has a
multiple forwarding database, you can use a separate interface for
each VLAN. Since the switch at the other end has a separate MAC
address table for each VLAN, the fact that the router uses the same
MAC address on all interfaces causes no problems.
4108GL Switch
VLAN 1 VLAN 2
5300xl, 3400cl, or 6400cl
Switch (Routing Enabled)
VLAN 1
VLAN 2
Both switches have
multiple forwarding
databases.
Figure 12-6. Example of a Valid Topology for Devices Having Multiple Forwarding
Databases in a Multiple VLAN Environment
As of this printing, the HP Procurve switches having a multiple
forwarding database include:
■ Series 5300XL ■ Series 3400cl ■ Switch 6108
■ Series 4100GL ■ Series 2600 ■ Series 6400cl
12-10