Re: Issues with IPTV Multicast between VLANs on Layer 3 Core Switch

franklvargas · ‎04-06-2023

Hello everyone,

We are currently facing an issue when attempting to transmit IPTV Multicast between different VLANs in our network. When we connect the devices directly to the source VLAN, everything works fine; however, we cannot receive the multicast service on other VLANs.

The IPTV Multicast service is provided by a router from our service provider, which is connected to a Layer 3 core switch in our network. The current configuration on our core switch is as follows:

ip multicast-routing
ip routing
ip igmp snooping
ip igmp snooping vlan 200
ip igmp snooping vlan 100

interface Vlan200
ip address 10.100.0.1 255.255.255.255
ip pim sparse-dense-mode

interface Vlan100
ip address 192.168.1.100 255.255.255.255
ip pim sparse-dense-mode

With this configuration, devices on VLAN 100 cannot access the multicast service. Am I missing any additional configuration on the core switch? Also, do I need to configure anything else on the other switches in the network besides IGMP Snooping?

I would greatly appreciate any suggestions or assistance in resolving this issue.

Best regards.

Kanan Huseynli · ‎04-06-2023

Hi,

check whether vlan100 users are joined to group or not:

show ip igmp groups

then check routing with sh ip mroute

HTH,
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franklvargas · ‎04-06-2023

Hello Kanan,

This is the result of the command sh ip mroute

Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode

(*, 239.255.255.250), 00:05:06/00:02:17, RP 10.100.0.1, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 00:05:06/00:02:17

(*, 234.1.1.1), 00:04:34/00:02:17, RP RP 10.100.0.1, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 00:04:34/00:02:17

(*, 224.0.1.40), 00:06:50/00:02:15, RP RP 10.100.0.1, flags: SJCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 00:06:50/00:02:09

franklvargas · ‎04-06-2023

SW-CORE#sho ip igmp groups
IGMP Connected Group Membership
Group Address Interface Uptime Expires Last Reporter Gr oup Accounted
239.255.255.250 Vlan100 00:30:57 00:02:22 192.168.1.100
234.1.1.1 Vlan100 00:30:25 00:02:19 192.168.1.100
224.0.1.40 Vlan200 00:32:39 00:02:22 10.100.0.254
224.0.1.40 Vlan100 00:32:41 00:02:20 192.168.1.100

Kanan Huseynli · ‎04-06-2023

Do I correctly understand that provider sends multicast over VLAN 200? And you have receivers both in vlan 200 and vlan 100?

What is multicast IP (I suppose, 234.1.1.1), ping that address with source vlan 200, then check show ip mroute

HTH,
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franklvargas · ‎04-06-2023

Hi Kanan,

That's right, we receive the service via vlan 200. We only have receivers in vlan 100, vlan 200 we have no receivers.

SW-CORE#ping 234.1.1.1 source vlan
SW-CORE#ping 234.1.1.1 source vlan 200
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 234.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 10.100.0.1
.
SW-CORE#sh ip mr
SW-CORE#sh ip mrou
SW-CORE#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, 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

(*, 239.255.255.250), 01:19:04/00:02:14, RP 10.100.0.1, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 01:19:04/00:02:14

(*, 234.1.1.1), 01:18:32/stopped, RP 10.100.0.1, flags: SJC
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 01:18:32/00:02:19

(10.100.0.1, 234.1.1.1), 00:00:20/00:02:39, flags: JT
Incoming interface: Vlan200, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 00:00:20/00:02:39, A

(*, 224.0.1.40), 01:20:48/00:02:19, RP 10.100.0.1, flags: SJCL
Incoming interface: Null, RPF nbr 0.0.0.0
Outgoing interface list:
Vlan100, Forward/Sparse-Dense, 01:20:48/00:02:16

Kanan Huseynli · ‎04-06-2023

What is source that that provider sends traffic? Is it known?

And what sh ip pim neighbor show (most probably you dont do neighboring with isp)?

Plus, is traffic routed further or only on vlan 100 you have receivers?

HTH,
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franklvargas · ‎04-06-2023

Hi Kana, Thank you for your prompt response

the source would be 10.100.0.254, we have a router installed by the provider with this DHCP addressing connected to vlan 200 of the CORE switch, the provider's router has as GW the 10.100.0.254.

SW-CORE#sh ip pim neighbor
PIM Neighbor Table
Mode: B - Bidir Capable, DR - Designated Router, N - Default DR Priority,
P - Proxy Capable, S - State Refresh Capable, G - GenID Capable,
L - DR Load-balancing Capable
Neighbor Interface Uptime/Expires Ver DR
Address Prio/Mode
10.100.0.254 Vlan200 02:22:51/00:01:35 v2 1 / DR S P G
SW-CORE#

franklvargas · ‎04-06-2023

the multicast ISP's router, should the IPTV network know the vlan 100?

Kanan Huseynli · ‎04-06-2023

So, you even have neighboring with ISP, based on output RP is "10.100.0.1", switch vlan 200 SVI.

Does ISP know it? Do they run sparse mode? Could you show sh ip pim rp mapping 234.1.1.1 from your device?

In general, how it is supposed to be run or how does it designed (RP, pim neighboring etc.).

HTH,
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franklvargas · ‎04-06-2023

I do not have access to the ISP router, I would have to request it, but I am sure I do not configure the vlan 100 network on your device, I have to ask the provider to do it?

From Switch-core this is the result of the command sh ip pim rp mapping 234.1.1.1

SW-CORE#sh ip pim rp mapping 234.1.1.1
PIM Group-to-RP Mappings

Group(s): 224.0.0.0/4, Static
RP: 10.100.0.1

Kanan Huseynli · ‎04-06-2023

Hi,

hmm..looks like nothing is negotiated. Is it only multicast traffic that runs on your network? Do you do mcast routing for other services (i.e IP addresses)? If not, remove rp configuration, then group 234.1.1.1 will fallback to dense mode and it should work.

HTH,
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franklvargas · ‎04-07-2023

Hi Kanan,

Yes, we have a DHCP server on vlan 100 for the TVs, to give them internet access independent of the multicast service (Youtube, Netflix, etc).

We tried removing rp-address and it does not work either.

Kanan Huseynli · ‎04-08-2023

Please, ask ISP to check what is multicast source.

I suspect RPF issue (switch receives multicast packet with source a.b.c.d but source does not pass RPF check).

You may also do "debug ip mfib pak [group_address]" and see what logs are generated when ISP sends traffic.

HTH,
Please rate and mark as an accepted solution if you have found any of the information provided useful.