Two PIM routers are neighbors if there is a direct connection between them. To display your PIM neighbors,
use the
show pim neighbor
command in EXEC mode.
Tip
Figure 4: Designated Router Election on a Multiaccess Segment
DR election process is required only on multiaccess LANs. The last-hop router directly connected to the
host is the DR.
Note
Rendezvous Points
When PIM is configured in sparse mode, you must choose one or more routers to operate as a rendezvous
point (RP). A rendezvous point is a single common root placed at a chosen point of a shared distribution tree,
as illustrated in
Figure 3: Shared Tree and Source Tree (Shortest Path Tree), on page 13
. A rendezvous point
can be either configured statically in each box or learned through a dynamic mechanism.
PIM DRs forward data from directly connected multicast sources to the rendezvous point for distribution
down the shared tree. Data is forwarded to the rendezvous point in one of two ways:
•
Encapsulated in register packets and unicast directly to the rendezvous point by the first-hop router
operating as the DR.
•
Multicast forwarded by the RPF forwarding algorithm, described in the
page 18
, if the rendezvous point has itself joined the source tree.
Cisco IOS XR Multicast Configuration Guide for the Cisco CRS Router, Release 5.2.x
16
Implementing Multicast Routing on Cisco IOS XR Software
Rendezvous Points