- Traffic is only routed via RP there is no switch to shortest tree
- Source Continiously passes traffic up to the RP irregardless if host are requesting
- Used in many to many implementations
- Traffic is forwarded solely on (*,G) no (S,G) enteries
- RPF is not required as the path is always via the RP
- Each segement elects a DF forwarder based on highest ip for forwarding onto the segement
- RP has increased criticality in the opertation as all data plane traffic is now also flowing through it
- As we have no (S,G) typical redudancy techniques for RP (MSDP/Anycast) do not function
- To allow redudancy we have phantom RP
- 2 modes of Phantom RP are
- Phantom RP Physical Interface- phantom rp use an ip address in a particular subnet but not one associated with physical interface this mean the RP address can be reached as one physical router connected to the subnet remains up
- Redudant Phantom Rp-Longest Match- same loopback on rp with longer subnet. Route with longest subnet match will always be first then if that goes down next router with longest subnet mask will take over
Commands
ip pim bidire-enable
int f0/0
ip pim sparse-mode
ip pim rp-address 1.1.1.1 bidir
LAB
OK for the lab i will enable bidirectional pim and we will join a few groups
I have already previous lab have a rp setup on everyone via r5 but i will need to edit that for bidirectional pim
so firstly on r5
r5
---
it is simple to turn on you enable
r5(config)#ip pim bidir-enable
FOr the rp advertisement i need to edit the rp-canidate to advertise bidirectional
r5(config)#ip pim rp-candidate lo0 bidir
on the interface it is just the same having pim sparse mode enabled i need to do this only routers in the topology
SO i need to enable ip pim bidire-enable on all the routers
from switch 4 i will do a join message
s4
----
s4(config-if)#int po2
s4(config-if)#ip igmp join-group 226.1.1.2
s4(config-if)#
As normal we have (*,G) for the group
s4#sh ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 226.1.1.2), 00:00:17/00:02:42, RP 5.5.5.5, flags: BPL
Bidir-Upstream: Port-channel2, RPF nbr 155.0.108.2
Outgoing interface list:
Port-channel2, Bidir-Upstream/Sparse, 00:00:17/00:00:00
(*, 224.0.1.40), 00:59:09/00:02:26, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Port-channel2, Forward/Sparse, 00:59:09/00:02:26
r5
---
r5#sh ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 226.1.1.2), 00:00:52/00:02:37, RP 5.5.5.5, flags: B
Bidir-Upstream: Null, RPF nbr 0.0.0.0
Outgoing interface list:
FastEthernet0/0, Forward/Sparse, 00:00:52/00:02:37
(*, 224.0.1.40), 01:00:16/00:02:53, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Serial0/0/0, Forward/Sparse, 00:55:37/00:02:53
Serial0/1/0, Forward/Sparse, 01:00:13/00:01:38
r5#
same on r5
sw3
====
Lets go to sw3 and originate some traffic
At the moment as normal we have no reference to the group
s3#sh ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 224.0.1.40), 00:59:54/00:02:31, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan79, Forward/Sparse, 00:59:54/00:02:31
s3#ping 226.1.1.2 repeat 10000
Type escape sequence to abort.
Sending 10000, 100-byte ICMP Echos to 226.1.1.2, timeout is 2 seconds:
................
s1
===
on s1 which is in the transit path in typical sparse mode we would see (S,G)
s1#sh ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 226.1.1.2), 00:00:47/00:02:51, RP 5.5.5.5, flags: BP
Bidir-Upstream: Vlan67, RPF nbr 155.0.67.6
Outgoing interface list:
Vlan67, Bidir-Upstream/Sparse, 00:00:47/00:00:00
(*, 224.0.1.40), 01:02:48/00:02:44, RP 0.0.0.0, flags: DPL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null
in bidrectional mode we see (*,G)
s1#sh ip pim int df
* implies this system is the DF
Interface RP DF Winner Metric Uptime
Vlan67 5.5.5.5 155.0.67.6 2300416 00:00:18
Vlan79 5.5.5.5 *155.0.79.1 2300672 00:00:18
s1#
we can also see for vlan 79 it has been selected as desginated forwarder for the segment
r5
--- RP
r5#sh ip mroute
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 226.1.1.2), 01:09:45/00:03:09, RP 5.5.5.5, flags: B
Bidir-Upstream: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Serial0/1/0, Forward/Sparse, 00:31:39/00:02:37
(*, 224.0.1.40), 02:18:29/00:02:40, RP 0.0.0.0, flags: DCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
FastEthernet0/0, Forward/Sparse, 00:56:58/00:02:17
Serial0/0/0, Forward/Sparse, 02:13:51/00:02:40
r5#
there is no source specfic routes there is only the shared tree route all traffic goes to the rp from the source and there is no shortest path tree
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