Design Reference

• Do not configure dual redundant RPs.
One vIST peer is the RP for a group.
• Do not configure one vIST peer as both the DR for the source VLAN and the RP for the
receiver group.
The system forwards the traffic to the RP or to the DR, depending on which peer receives the
source, and, if the SMLT link to the receiver goes down there will be no data loss.
PIM-SM and static RP
Use static RP to provide security, interoperability, and redundancy for PIM-SM multicast networks.
Consider if the administrative ease derived from using dynamic RP assignment is worth the security
risks involved. For example, if an unauthorized user connects a PIM-SM router that advertises itself
as a candidate RP (C-RP), it can possibly take over new multicast streams that otherwise distribute
through an authorized RP. If security is important, use static RP assignment.
You can use the static RP feature in a PIM environment with devices that run legacy PIM-SMv1 and
auto-RP (a proprietary protocol that Virtual Services Platform 4000 does not support). For faster
convergence, you can also use static RP in a PIM-SMv2 environment. If you configure static RP
with PIM-SMv2, the BSR is not active.
Static RP and auto-RP
Some legacy PIM-SMv1 networks use the auto-RP protocol. Auto-RP is a Cisco proprietary protocol
that provides equivalent functionality to the standard Virtual Services Platform 4000 PIM-SM RP and
BSR. You can use the static RP feature to interoperate in this environment. For example, in a
mixed-vendor network, you can use auto-RP among routers that support the protocol, while other
routers use static RP. In such a network, ensure that the static RP configuration mimics the
information that is dynamically distributed to guarantee that multicast traffic is delivered to all parts
of the network.
In a mixed auto-RP and static RP network, ensure that Virtual Services Platform 4000 does not
serve as an RP because it does not support the auto-RP protocol. In this type of network, the RP
must support the auto-RP protocol.
Static RP and RP redundancy
You can provide RP redundancy through static RPs. To ensure consistency of RP selection,
implement the same static RP configuration on all PIM-SM routers in the network. In a mixed vendor
network, ensure that the same RP selection criteria is used among all routers. For example, to
select the active RP for each group address, the switch uses a hash algorithm defined in the PIM-
SMv2 standard. If a router from another vendor selects the active RP based on the lowest IP
address, then the inconsistency prevents stream delivery to certain routers in the network.
If a group address-to-RP discrepancy occurs among PIM-SM routers, network outages occur.
Routers that are unaware of the true RP cannot join the shared tree and cannot receive the
multicast stream.
Failure detection of the active RP is determined by the unicast routing table. As long as the RP is
considered reachable from a unicast routing perspective, the local router assumes that the RP is
fully functional and attempts to join the shared tree of that RP.
The following figure shows a hierarchical OSPF network where a receiver is in a totally stubby area.
If RP B fails, PIM-SM router A does not switch over to RP C because the injected default route in
the unicast routing table indicates that RP B is still reachable.
IP multicast network design
138 Network Design Reference for Avaya VSP 4000 Series June 2015
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