Multicast sparse-mode and PIM bidirectional

[angelayan]

In the same PIM domain, some router has PIM directional enabled and some routers are not. 

What will be the final mode the Multicast protocol will be using build trees with the same RP and for the Multicast to work properly?

[Georg Pauwen · Accepted solution]

Hello,

I tested this in GNS3, with IGMP group 239.1.1.1 connected to a PIM bidirectional enabled router, and IGMP group 239.2.2.2 connected to a non-bidirectional router. The output (below) is identical:

R1#sh ip mroute 239.2.2.2
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

(*, 239.2.2.2), 00:03:22/00:03:24, RP 1.1.1.1, flags: B
Bidir-Upstream: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet0/0, Forward/Sparse, 00:03:22/00:03:24

R1#sh ip mroute 239.1.1.1
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), 00:03:22/00:03:22, RP 1.1.1.1, flags: B
Bidir-Upstream: Null, RPF nbr 0.0.0.0
Outgoing interface list:
GigabitEthernet0/1, Forward/Sparse, 00:03:22/00:03:22

[angelayan]

Thanks a lot. Georg.



So that means, if in a PIM Domain, there are mixed PIM-SM and PIM-BIDIR. PIM-BIDIR overrides PIM-SM.

[Georg Pauwen]

Hello,

that's what it looks like...

Is that an exam question, or do you have a specific requirement to mix both ?

[angelayan]

It is a special environment requirement.

[Georg Pauwen]

Hello,

I need to reverse my findings. I added a couple of more routers, and when I take 'ip pim bidir-enable' off one of the routers, the outgoing interface is null (see output below). So it looks like it needs to be enabled on all routers in the domain...

R1#sh ip mroute 239.3.3.3
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

(*, 239.3.3.3), 00:11:27/00:02:51, RP 1.1.1.1, flags: BP
Bidir-Upstream: Null, RPF nbr 0.0.0.0
Outgoing interface list: Null