Viewing the multicast routing table (FGT-3)
The FGT-3 unicast routing table can be used to determine the path taken to reach the RP at 192.168.1.1. You can then check the stream state entries using the following commands:
FGT-3 # get router info multicast pim sparse-mode table
IP Multicast Routing Table
(*,*,RP) Entries: 0
(*,G) Entries: 1
(S,G) Entries: 1
(S,G,rpt) Entries: 1
FCR Entries: 0
(*,*,RP) Entries | This state may be reached by general joins for all groups served by a specified RP. |
(*,G) Entries | State that maintains the RP tree for a given group. |
(S,G) Entries | State that maintains a source-specific tree for source S and group G. |
(S,G,rpt) Entries | State that maintains source-specific information about source s on the RP tree for G. For example, if a source is being received on the source-specific tree, it will normally have been pruned off the RP tree. |
FCR | The FCR state entries are for tracking the sources in the <*, G> when <S, G> is not available for any reason, the stream would typically be flowing when this state exists. |
Breaking down each entry in detail:
(*, 239.255.255.1)
RP: 192.168.1.1
RPF nbr: 10.132.0.156
RPF idx: port2
Upstream State: JOINED
Local:
port3
Joined:
Asserted:
FCR:
The RP will always be listed in a *,G entry, the RPF neighbor and interface index will also be shown. In this topology these are the same in all downstream PIM routers. The state is active so the upstream state is joined.
In this case FGT-3 is the last hop router so the IGMP join is received locally on port3. There is no PIM outgoing interface listed for this entry as it is used for the upstream PIM join.
(10.166.0.11, 239.255.255.1)
RPF nbr: 10.132.0.156
RPF idx: port2
SPT bit: 1
Upstream State: JOINED
Local:
Joined:
Asserted:
Outgoing:
port3
This is the entry for the SPT, no RP IS listed. The S,G stream will be forwarded out of the stated outgoing interface.
(10.166.0.11, 239.255.255.1, rpt)
RP: 192.168.1.1
RPF nbr: 10.132.0.156
RPF idx: port2
Upstream State: NOT PRUNED
Local:
Pruned:
Outgoing:
The above S,G,RPT state is created for all streams that have both a S,G and a *,G entry on the router. This is not pruned in this case because of the topology, the RP and source are reachable over the same interface.
Although not seen in this scenario, assert states may be seen when multiple PIM routers exist on the same LAN which can lead to more than one upstream router having a valid forwarding state. Assert messages are used to elect a single forwarder from the upstream devices.