Multicast? Is flooding the router (500Mbps sustained)

Alkemyst71 · ‎06-23-2020

We are deploying a video solution using SnapAV Binary MoiPs. We have 4 sources on (2 Xfinity cable, 2 Apple TV). The router was only doing about 20MB/s until we enabled jumbo frames on the LAN interface. Now it's at a constant 500MB and no one is even at the location. We are not sure why that traffic is not just staying on the switches since it's all on one VLAN. We have tried to take off the ip pim sparse-dense from Gi0/0 (lan) and the Gi0/0.30 (vlan subinterface) and the IGMP groups and PIM Neighbors drop, but the traffic still continues

We believe we only need multicast for VLAN 30 (the AV VLAN).

Here are the relevant parts of the configs:

interface GigabitEthernet0/0
description LAN - Uplink to 2960X_1 G1/0/1
mtu 9216
no ip address
ip flow ingress
ip flow egress
ip pim sparse-dense-mode
ip nat inside
ip virtual-reassembly in
load-interval 30
duplex auto
speed auto
!
interface GigabitEthernet0/0.30
description AV
encapsulation dot1Q 30
ip address 10.31.204.1 255.255.255.0
ip flow ingress
ip flow egress
ip pim sparse-dense-mode
ip nat inside
ip virtual-reassembly in
!

Switch

ip multicast-routing distributed
ip igmp snooping querier address 10.31.204.254
ip igmp snooping querier query-interval 30
ip igmp snooping querier
ip igmp snooping vlan 1 immediate-leave
ip igmp snooping vlan 10 immediate-leave
ip igmp snooping vlan 20 immediate-leave
ip igmp snooping vlan 30 immediate-leave

!

interface Vlan30
ip address 10.31.204.254 255.255.255.0
ip pim dr-priority 3
ip pim sparse-dense-mode
!

Giuseppe Larosa · ‎06-24-2020

Hello @Alkemyst71 ,

on the switch you should remove

>> ip igmp snooping querier address 10.31.204.254

Because the router on its subinterface when you enable PIM you also enable IGMP at the same time so the IGMP snooping querier is not needed and Cisco recommends to avoid to have two queriers in the same Vlan.

Hope to help

Giuseppe

Alkemyst71 · ‎06-24-2020

Thanks, the bandwidth is still at 500MB+, but we removed the querier address.

This is the rest of the current config with igmp:

ip multicast-routing distributed
ip igmp snooping querier query-interval 30
ip igmp snooping querier
ip igmp snooping vlan 1 immediate-leave
ip igmp snooping vlan 10 immediate-leave
ip igmp snooping vlan 20 immediate-leave
ip igmp snooping vlan 30 immediate-leave

Alkemyst71 · ‎06-24-2020

My show statements:

show ip igmp snooping querier det

Vlan IP Address IGMP Version Port
-------------------------------------------------------------
1 10.31.201.5 v2 Switch
10 10.31.201.5 v2 Switch
20 10.31.201.5 v2 Switch
30 10.31.204.1 v2 Gi1/0/1

Global IGMP switch querier status
--------------------------------------------------------
admin state : Enabled
admin version : 2
source IP address : 0.0.0.0
query-interval (sec) : 30
max-response-time (sec) : 10
querier-timeout (sec) : 120
tcn query count : 2
tcn query interval (sec) : 10

Vlan 1: IGMP switch querier status
--------------------------------------------------------
elected querier is 10.31.201.5 (this switch querier)
--------------------------------------------------------
admin state : Enabled (state inherited)
admin version : 2
source IP address : 10.31.201.5
query-interval (sec) : 30
max-response-time (sec) : 10
querier-timeout (sec) : 120
tcn query count : 2
tcn query interval (sec) : 10
operational state : Querier
operational version : 2
tcn query pending count : 0

Vlan 10: IGMP switch querier status
--------------------------------------------------------
elected querier is 10.31.201.5 (this switch querier)
--------------------------------------------------------
admin state : Enabled (state inherited)
admin version : 2
source IP address : 10.31.201.5
query-interval (sec) : 30
max-response-time (sec) : 10
querier-timeout (sec) : 120
tcn query count : 2
tcn query interval (sec) : 10
operational state : Querier
operational version : 2
tcn query pending count : 0

Vlan 20: IGMP switch querier status
--------------------------------------------------------
elected querier is 10.31.201.5 (this switch querier)
--------------------------------------------------------
admin state : Enabled (state inherited)
admin version : 2
source IP address : 10.31.201.5
query-interval (sec) : 30
max-response-time (sec) : 10
querier-timeout (sec) : 120
tcn query count : 2
tcn query interval (sec) : 10
operational state : Querier
operational version : 2
tcn query pending count : 0

Vlan 30: IGMP switch querier status
--------------------------------------------------------
admin state : Enabled (state configured)
admin version : 2
source IP address : 10.31.204.254
query-interval (sec) : 30
max-response-time (sec) : 10
querier-timeout (sec) : 120
tcn query count : 2
tcn query interval (sec) : 10
operational state : Disabled
operational version : 2
tcn query pending count : 0

show 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
10.31.204.1 Vlan30 1d02h/00:01:17 v2 1 / S P G
10.31.204.253 Vlan30 5d20h/00:01:26 v2 1 / S P G

show ip igmp snooping det
Global IGMP Snooping configuration:
-------------------------------------------
IGMP snooping : Enabled
IGMPv3 snooping (minimal) : Enabled
Report suppression : Enabled
TCN solicit query : Disabled
TCN flood PortFast : Disabled
TCN flood query count : 2
Robustness variable : 2
Last member query count : 2
Last member query interval : 1000
Extended flooding after
mrouter detected (sec) : 0

Vlan 1:
--------
IGMP snooping : Enabled
IGMPv2 immediate leave : Enabled
Multicast router learning mode : pim-dvmrp
CGMP interoperability mode : IGMP_ONLY
Robustness variable : 2
Last member query count : 2
Last member query interval : 1000
Topology change : No
Vlan 10:
--------
IGMP snooping : Enabled
IGMPv2 immediate leave : Enabled
Multicast router learning mode : pim-dvmrp
CGMP interoperability mode : IGMP_ONLY
Robustness variable : 2
Last member query count : 2
Last member query interval : 1000
Topology change : No
Vlan 20:
--------
IGMP snooping : Enabled
IGMPv2 immediate leave : Enabled
Multicast router learning mode : pim-dvmrp
CGMP interoperability mode : IGMP_ONLY
Robustness variable : 2
Last member query count : 2
Last member query interval : 1000
Topology change : No
Vlan 30:
--------
IGMP snooping : Enabled
IGMPv2 immediate leave : Enabled
Multicast router learning mode : pim-dvmrp
CGMP interoperability mode : IGMP_ONLY
Robustness variable : 2
Last member query count : 2
Last member query interval : 1000
Topology change : No

Alkemyst71 · ‎06-24-2020

so I took out the snooping on all VLANs except 30 since that is the only one that needed it. I removed pim sparse-dense mode from the router interfaces and left it only on the SVI's of both switches for VLAN 30. Only switch 1 has the querier commands (I cannot do it for VLAN 30 as it tells me PIM is set on the SVI. Oddly the company that supports the multi-cast devices says to make sure PIM is enabled and a querier is set.

My bandwidth has gone from 500-600MB/s on the router to 50-60k. I am thinking there was some kind of multicast storm going on.

I am still no sure if my configuration is ideal or not.

Alkemyst71 · ‎06-24-2020

Relevant configs now

Switch 1

ip multicast-routing distributed
ip igmp snooping querier query-interval 30
ip igmp snooping querier
ip igmp snooping vlan 30 immediate-leave

!

interface GigabitEthernet1/0/xx
description AV
switchport access vlan 30
switchport mode access
load-interval 30

!

interface Vlan30
ip address 10.31.204.254 255.255.255.0
ip pim dr-priority 3
ip pim sparse-dense-mode

!

Switch 2

ip multicast-routing distributed
ip igmp snooping vlan 30 immediate-leave

!

interface GigabitEthernet1/0/xx
description AV
switchport access vlan 30
switchport mode access
load-interval 30

!

interface Vlan30
ip address 10.31.204.253 255.255.255.0
ip pim sparse-dense-mode

Giuseppe Larosa · ‎06-25-2020

Hello @Alkemyst71 ,

what you see is caused by the way that IGMP snooping works:

if a multicast router is detected over a swich port that swich port will be member of every multicast group.

The detection is based on receiving IGMP or PIM messaged on the port.

The reason is that the switch provides to a multicast enabled router all the multicast user traffic and that it is then the router to decide which flows should be forwarded to other interfaces.

In the moment that you have disabled PIM on the router subinterface the switch port status changed to that of a normal host and all this multicast flooding had stopped.

Because no PIM messages or IGMP messages are received on the switch port connected to the router.

This configuration is correct until no multicast flows need to exit via the router to reach other sites.

Hope to help

Giuseppe

Alkemyst71 · ‎06-25-2020

Thanks again, my first time configuring multicast.