Brocade Network OS Administrator’s Guide v4.1.1 - Manual (Page 577)

• PIM can be enabled on all Brocade VDX 8770 or VDX 6740 models where VRRP-E is enabled.
• PIM DR-priority is configured on ve interfaces of all PIM-capable aggregation routers to optimize
load-sharing abilities within the aggregation.
PIM Sparse device types
Devices that are configured with PIM Sparse interfaces also can be configured to fill one or more of the
following roles:
• PIM multicast border router (PMBR) — A PIM device that has interfaces within the PIM domain and
other interface outside the PIM domain. PBMRs connect the PIM domain to the Internet.
• Bootstrap router (BSR) — A router that distributes rendezvous point (RP) information to the other
PIM Sparse devices within the domain. Each PIM Sparse domain has one active BSR. For
redundancy, you can configure ports on multiple devices as candidate BSRs. The PIM Sparse
protocol uses an election process to select one of the candidate BSRs as the BSR for the domain.
The BSR with the highest BSR priority (a user-configurable parameter) is elected. If the priorities
result in a tie, then the candidate BSR interface with the highest IP address is elected.
The BSR must be configured as part of the L3 core network.
• Rendezvous point (RP) — The meeting point for PIM Sparse sources and receivers. A PIM Sparse
domain can have multiple RPs, but each PIM Sparse multicast group address can have only one
active RP. PIM Sparse devices learn the addresses of RPs and the groups for which they are
responsible from messages that the BSR sends to each of the PIM Sparse devices.
The RP must be configured as part of the L3 core network.
NOTE
Brocade recommends that you configure the same ports as candidate BSRs and RPs.
• PIM designated router (DR) — Once the RP has been identified, each interested host and/or router
sends join messages to the RP for the group that they are interested in. The local network selects
one of its upstream routers as the designated router (DR). All hosts below a DR send IGMP join
messages to the DR. The DR in turn sends only one join message to the RP on behalf of all its
interested hosts. The RP receives the first few packets of the multicast stream, encapsulated in the
PIM register message, from the source hosts. These messages are sent as a unicast to the RP. The
RP de-encapsulates these packets and forwards them to the respective DRs.
NOTE
DR election is based first on the router with the highest configured DR priority for an interface (if DR
priority has been configured), and based next on the router with the highest IP address. To configure
DR priority, use the ip pim dr-priority command. For more information about this command, refer to
Network OS Command Reference.
PIM prerequisites
PIM requires the following to function properly:
• The system should support receiving and transmitting unicast as well as multicast packets.
• A Routing Information Base (RIB) must be accessible for obtaining routing information.
• An IPC mechanism must be available.
PIM Sparse device types
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