Hi All,
A newbie in multicast and started playing around with sparse-mode.
I have attached a sample diagram.
Brief summary:
R1- IGMP router for source (R5 is simulatyed multicast source)
R2- Rendez-vous point
R3- Upstream Mcast router to R4
R4- IGMP router for receiver (R6 is a simulated multicast receiver)
R5- Mutlicast source
R6- Multicast receiver
Shortest path from receiver to source is R6->R4->R1->R5.
Providing the show ip mroute from R1, R2, R3, R4 routers:
R1#show 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, E - Extranet,
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,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:10:49/stopped, RP 11.1.1.1, flags: SPF
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.1.2
Outgoing interface list: Null
(20.1.1.2, 239.1.1.1), 00:10:49/00:02:47, flags: FT
Incoming interface: GigabitEthernet0/3, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet0/2, Forward/Sparse, 00:10:49/00:02:35
(*, 224.0.1.40), 00:15:08/00:02:54, RP 11.1.1.1, flags: SJPL
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.1.2
Outgoing interface list: Null
R2#show 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, E - Extranet,
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,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:11:42/00:02:45, RP 11.1.1.1, flags: S
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet0/1, Forward/Sparse, 00:11:42/00:02:45
(20.1.1.2, 239.1.1.1), 00:11:25/00:01:53, flags: PT
Incoming interface: GigabitEthernet0/2, RPF nbr 10.1.1.1
Outgoing interface list: Null
(*, 224.0.1.40), 00:15:48/00:02:40, RP 11.1.1.1, flags: SJCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet0/2, Forward/Sparse, 00:15:42/00:02:31
GigabitEthernet0/1, Forward/Sparse, 00:15:47/00:02:40
R3#show 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, E - Extranet,
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,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:11:50/00:02:36, RP 11.1.1.1, flags: S
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.2.1
Outgoing interface list:
GigabitEthernet0/2, Forward/Sparse, 00:11:50/00:02:36
(20.1.1.2, 239.1.1.1), 00:11:31/00:02:36, flags: PR
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.2.1
Outgoing interface list: Null
(*, 224.0.1.40), 00:15:50/00:02:59, RP 11.1.1.1, flags: SJCL
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.2.1
Outgoing interface list:
GigabitEthernet0/2, Forward/Sparse, 00:14:57/00:02:42
R4#show 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, E - Extranet,
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,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.1.1.1), 00:12:06/stopped, RP 11.1.1.1, flags: SJC
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.3.1
Outgoing interface list:
GigabitEthernet0/3, Forward/Sparse, 00:12:06/00:02:54
(20.1.1.2, 239.1.1.1), 00:11:50/00:02:44, flags: JT
Incoming interface: GigabitEthernet0/2, RPF nbr 10.1.4.1
Outgoing interface list:
GigabitEthernet0/3, Forward/Sparse, 00:11:50/00:02:54
(*, 224.0.1.40), 00:15:56/00:02:49, RP 11.1.1.1, flags: SJPCL
Incoming interface: GigabitEthernet0/1, RPF nbr 10.1.3.1
Outgoing interface list: Null
What i have undertood is below:
R1 and R4 have pruned themselves from shared tree and traffic is now distributing itself through shortest path tree
What i don't understand is:
R2 (RP) and R3:
R2 and R3 is still part of the shared tree even though the last time they have forwarded the traffic for that multicast group is approx 11 minutes as per the show ip mroute command, my understanding is that if a PIM router does not forward a traffic for 3 minutes, it will leave the tree ?
I guess my question is, shouldn't R2 and R3 leave the shared tree after the 3 minute interval ?
Thank you for your help.
