HP 3500YL - Manual (Page 116)

PIM-SM (Sparse Mode)
PIM-SM Operation and Router Types
Border Routers and Multiple PIM-SM Domains
Creating multiple domains enables a balancing of PIM-SM traffic within a
network. Defining PIM-SM domain boundaries requires the use of PIM border
routers (PMBRs), and multiple PMBRs can be used between any two domains.
N o t e As of March 2006, the software covered by this guide does not support PMBR
operation for PIM-SM networks.
PIM-SM Router Types
Within a PIM-SM domain, PIM-SM routers can be configured to fill one or more
of the roles described in this section.
■ Designated Router (DR): A router performing this function forwards
multicast traffic from a unicast source to the appropriate distribution
(rendezvous) point. Refer to “Designated Router (DR)”, below.
■ Bootstrap Router (BSR): A router elected to this function keeps all
routers in a PIM-SM domain informed of the currently assigned RP for
each multicast group currently known in the domain. Refer to “Bootstrap
Router (BSR)” on page 4-13.
■ Rendezvous Point (RP): A router elected as a rendezvous point for a
multicast group receives requested multicast traffic from a DR and for­
wards it toward the multicast receiver(s) requesting the traffic. Refer to
“Rendezvous Point (RP)” on page 4-14.
■ Static Rendezvous Point (Static-RP): This option forwards traffic in
the same way as an RP, but requires manual configuration on all routers
in the domain to be effective.
All of the above functions can be enabled on each of several routers in a PIM­
SM domain. For more information, refer to the following sections.
Designated Router (DR)
In a VLAN populated by one or more routers running PIM-SM, one such router
is elected the Designated Router (DR) for that VLAN. When the DR receives
a Join request from a multicast receiver on that VLAN, it forwards the Join
towards the router operating as the RP for the requested multicast group.
4-12