Re: IP Multicast - Sparse Mode not working

simoesmarco8626982 · ‎11-29-2020

Hi all,

hope you can help me.

I've spent the entire day trying to figure out what is wrong and can't seem to understand the issue

I have a system with several Ciscos 3650 Switches, I configured Auto RP on all the switches (for redundancy), and gave priority to one of them, and I think everything is well configured since when running the mtrace command I get this:

Cisco#mtrace 10.200.200.22
Type escape sequence to abort.
Mtrace from 10.200.200.22 to 10.7.254.3 via RPF
From source (?) to destination (?)
Querying full reverse path...
0 10.7.254.3
-1 10.7.254.3 ==> 10.7.254.3 PIM [10.200.200.22/32]
-2 10.7.254.2 ==> 10.6.254.3 PIM [10.200.200.22/32]
-3 10.6.254.2 ==> 10.1.254.11 PIM [10.200.200.22/32]
-4 10.1.254.10 ==> 10.200.200.22 PIM_MT [10.200.200.22/32]
-5 10.200.200.22

And this:

PIM Group-to-RP Mappings
This system is an RP (Auto-RP)
This system is an RP-mapping agent

Group(s) 224.0.0.0/4
RP 10.200.200.22 (?), v2v1
Info source: 10.200.200.22 (?), elected via Auto-RP
Uptime: 02:09:39, expires: 00:00:36
RP 10.200.200.21 (?), v2v1
Info source: 10.200.200.21 (?), via Auto-RP
Uptime: 02:06:57, expires: 00:00:32
RP 10.200.200.20 (?), v2v1
Info source: 10.200.200.20 (?), via Auto-RP
Uptime: 02:05:11, expires: 00:00:34
RP 10.200.200.19 (?), v2v1
Info source: 10.200.200.19 (?), via Auto-RP
Uptime: 02:03:32, expires: 00:00:43
RP 10.200.200.18 (?), v2v1
Info source: 10.200.200.18 (?), via Auto-RP
Uptime: 02:13:41, expires: 00:00:34
RP 10.200.200.17 (?), v2v1
Info source: 10.200.200.17 (?), via Auto-RP
Uptime: 02:19:19, expires: 00:00:38
RP 10.200.200.16 (?), v2v1
Info source: 10.200.200.16 (?), via Auto-RP
Uptime: 02:41:08, expires: 00:00:36

I configured all the vlan interfaces as IP pim sparse-mode and activated multicast routing in all the switches in the path and the interfaces as IP pim sparse-mode as well, but when I stream one camera configured with the group 232.9.40.110, I don't get any image in the receiver and when checking the mroute I get this:

(*, 232.9.40.110), 03:37:01/stopped, RP 10.200.200.22, flags: SPF
Incoming interface: Vlan4086, RPF nbr 10.7.254.2
Outgoing interface list: Null

(10.9.40.110, 232.9.40.110), 01:26:50/00:02:48, flags: PFT
Incoming interface: Vlan40, RPF nbr 0.0.0.0
Outgoing interface list: Null

From what I understand, it's pruned, but I don't know what more to do for the traffic to start forwarding.

If I put the system in PIM Dense Mode everything works just fine, but I want to avoid using this last

Hope anyone can help

Thank you

Giuseppe Larosa · ‎11-30-2020

Hello @simoesmarco8626982 ,

PIM Sparse mode is based on Explicit Joins to build the distribution tree that is the opposite of dense mode "flood and prune" you need a receiver that sends IGMP reports for group 232.9.40.110.

As a workaround you can configure an igmp static mapping on the SVI or L3 interface

interface vlan X

ip igmp join-group 232.9.40.110

In this way the OLIST for (S,G) should be not NULL anymore

Hope to help

Giuseppe

simoesmarco8626982 · ‎11-30-2020

Thank you Giuseppe that's very useful, is there a way of adding the entire 232 group? I have around 100 cameras in that vlan and creating a 232.x.x.x for every single one in the vlan is a nightmare. Thank you

Giuseppe Larosa · ‎11-30-2020

Hello @simoesmarco8626982 ,

the suggested command is not able to support groups of multicast addresses.

In addition there is a big drawback of this command: the swich becomes a member of the group and so the traffic of 100 cameras might be to too much to process in software for the mainc cpu of the switch.

So I see two options:

a) either you are able to have receivers that use IGMP and send reports for each camera to be able to use PIM sparse mode.

b) if the previous option is not possible it would be better to change to dense mode to avoid the need of Explicit IGMP Joins

Hope to help

Giuseppe

simoesmarco8626982 · ‎11-30-2020

Thank you once again for the reply, unfortunately I don't have receivers that use IGMP, and meanwhile since I wasn't reaching anywhere I passed all the switches and interfaces to IP pim sparse-dense-mode and it's now using dense mode, but I have one issue now and I can't figure out why... In the mroute all the group's and outgoing interfaces are in stopped mode, already did an mtrace and everything works and reaches the sender... The dense configuration doesn't have much to it, but I can't figure out why everything is stopped when I check the mroute...

Any ideas?

Thank you

mlund · ‎12-01-2020

Hi

With the command "ip igmp join-group", the mcast stream will hit the cpu, as mentioned by Giuseppe. But with command "ip igmp static-group" the stream will not hit cpu, it will only put in the interface in the outgoing-list.

Not sure about 3650, but try with something like this

class-map type multicast-flows CAMERAS

group 232.9.40.12 to 232.9.40.45

group 232.9.40.50

group 232.9.40.100 to 232.9.40.150

interface x/y

ip igmp static-group class-map CAMERAS

/Mikael

simoesmarco8626982 · ‎12-01-2020

Thank you very much for the reply.

I haven't implemented this because meanwhile I found that the issue it seems it's the software that I'm using to visualise the video cameras. If I use VLC using the same rtsp string everything works, but if I use the software that I should be using, the camera opens an rtsp connection that it says unassigned and no matter what I do this software always opens a bad connection like this and I can't understand why...