We are trying to get multicast support set up over multiple networks. Currently we have 2 RB953 routers set up. Each router manages 3 subnets (10.0.0.0/24, 10.0.1.0/24, 10.0.2.0/24 for router #0 and 10.1.0.0/24, 10.1.1.0/24 and 10.1.2.0/24 for router #1). We can ping & route traffic across networks correctly.
At the moment I’m just trying to get router #0 set up for multicasting. I’ve started PIM on all interfaces on router #0 and set 10.0.0.1 as the RP. When trying to send sACN (multicast address 239.255.0.1) we can see the group join appear but it still lists as ‘not joined’. Additionally when joining from 10.0.1.0/24 the group address seems to be incorrect - it shows up as 239.255.255.
After this, we need to make this work across both routers (e.g. traffic to 239.255.0.0/16 needs to be routed to all 10.0.0.0/8).
How can we make this work? Is this the wrong approach?
Thanks!
You don’t need to do any routes for the multicast addresses because multicast routing sort of works backwards from unicast routing. I.e. it routes away from the unicast IP of the source address. Essentially, a multicast packet for a given group will be forwarded to every subscribed port which is not the one which would be used to reach the source IP. The destination address doesn’t dictate the forwarding, except to determine which interfaces actually want it.
PIM is a dynamic routing protocol for Multicast, so it will take care of the proper routing for you automatically. What you need to do is make sure that router 1 and router 0 both use the same RP address so that the sparse forwarding tree can establish itself properly.
So long as the forwarding path between the two routers doesn’t have any filter rules that would block the traffic, you should be good to go.
OK - but I can’t even get it working within the same router. I don’t have any filter rules defined yet. Is there any reason that PIM would get an incorrect join IP?
It’d be better if I gave a better problem description.
I have 2 routers (RB953-5HnT-RP), router 0 and router 1. At the moment i’m focusing on router 1. Eventually I’ll need to get both working together.
The Ethernet interfaces are bridged to 10.x.0.0/24 (the router being 10.x.0.1), the WiFi interfaces are bridged to 10.x.1.0/24 (the router being 10.x.1.1), where x is the router number.
I have a sACN source on Ethernet (group 239.255.0.1 coming from 10.1.0.2) that i want routed over 10.1.1.0/24 in addition to 10.1.0.0/24.
Router 1 is currently the RP (10.1.0.1).
I’m seeing weird entries in the PIM join:
Flags: RP - (*,*,RP), WC - (*,G), SG - (S,G), SG_rpt - (S,G,rpt)
GROUP SOURCE RP
WC 224.0.0.0 10.1.0.1 10.1.0.1
SG_rpt 239.255.0.1 10.1.0.2 10.1.0.1
SG_rpt 239.255.255.250 10.1.1.254 10.1.0.1
Flags: X - disabled, I - inactive, D - dynamic, R - designated-router, v1 - IGMPv1, v2 - IGMPv2, v3 - IGMPv3
# INTERFACE PROTOCOLS
0 v2 all pim
igmp
1 D v2 sfp_bridge pim
igmp
2 DRv2 ether_bridge pim
igmp
3 D v2 wlan2 igmp
2 DR ether_bridge pim
1 DR sfp_bridge pim
4 DR register pim
The entry for 10.1.0.2 seems correct but 10.1.1.254 (WiFi client) is getting a weird group address.
Do i need to forward 224.0.0.0/4 somewhere?