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C3750X sees the IGMP querier changes between HSRP IPs

g748437
Level 1
Level 1

‎06-26-2023 12:36 PM - edited ‎06-26-2023 12:37 PM

Hello, 

I have a pair of Nexus 5548 in VPC and one VLAN used for multicast. A 3750X stack is connected to Nexus-1 and Nexus-2 through a port-channel. The issue I am seeing is that the 3750 sees the IGMP querier changes from time to time between the HSRP IPs of the SVIs:

IDF-3750X#sh ip igmp snooping querier | inc 819
819 172.30.19.2 v3 Po10
IDF-3750X#sh ip igmp snooping querier | inc 819
819 172.30.19.3 v3 Po10

IDF-3750X#sh ip igmp snooping querier vlan 819
IP address : 172.30.19.2
IGMP version : v3
Port : Po10
Max response time : 10s
Query interval : 125s
Robustness variable : 2

IDF-3750X#sh ip igmp snooping querier vlan 819
IP address : 172.30.19.3
IGMP version : v3
Port : Po10
Max response time : 10s
Query interval : 125s
Robustness variable : 2

SVIs are configured as follows:

CORE-1# sh run int vlan 819

interface Vlan819
description AUDIO
no shutdown
ip address 172.30.19.3/24
ip pim sparse-mode
ip pim dr-priority 10
ip igmp version 3
hsrp version 2
hsrp 819
preempt
ip 172.30.19.1

CORE-2# sh run int vlan 819

interface Vlan819
description AUDIO
no shutdown
ip address 172.30.19.2/24
ip pim sparse-mode
ip igmp version 3
hsrp version 2
hsrp 819
preempt
priority 110
ip 172.30.19.1

I did a pcap at the switch on each port-channel member on VLAN 819 and there are PIM hellos and IGMP query from each of the SVI IPs.

g748437_0-1687807706116.png

g748437_1-1687807741601.png

So is this expected? the switch keeps changing what IPs it sees as the querier and the traffic during those time are sent to new querier? How can I make this work to make the switch seeing a single querier all the time on that VLAN and if there is a failure then the standby HSRP IP being the querier.

the PIM-DR config I added to see if it helped but it didn't.

 

Thanks 

Thanks

 

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2 Replies 2

g748437
Level 1
Level 1

‎06-26-2023 12:55 PM

I discovered that each Nexus SVI from time to time see themselves as the active querier: (these output was taken at the same time) and during that brief time there was no querier showing on any of the Nexus:

CORE-1# sh ip igmp snooping querier | inc 819
CORE-1# sh ip igmp snooping querier
Vlan IP Address Version Expires Port
150 172.16.50.1 v2 00:02:34 Vlan150 (internal)
250 10.35.250.253 v2 00:02:49 Vlan250 (internal)
502 172.17.2.2 v2 00:02:48 Vlan502 (internal)
504 172.17.4.2 v2 00:02:37 Vlan504 (internal)

CORE-2# sh ip igmp snooping querier
Vlan IP Address Version Expires Port
150 172.16.50.1 v2 00:03:59 port-channel4096
250 10.35.250.253 v2 00:04:01 port-channel4096
502 172.17.2.2 v2 00:04:10 port-channel4096
504 172.17.4.2 v2 00:04:06 port-channel4096

CORE-1# sh ip igmp interface vlan 819
IGMP Interfaces for VRF "default"
Vlan819, Interface status: protocol-up/link-up/admin-up
IP address: 172.30.19.3, IP subnet: 172.30.19.0/24
Active querier: 172.30.19.3, version: 3, next query sent in: 00:00:10
Membership count: 67
Old Membership count 0
IGMP version: 3, host version: 3
IGMP query interval: 125 secs, configured value: 125 secs
IGMP max response time: 10 secs, configured value: 10 secs
IGMP startup query interval: 31 secs, configured value: 31 secs
IGMP startup query count: 2
IGMP last member mrt: 1 secs
IGMP last member query count: 2
IGMP group timeout: 260 secs, configured value: 260 secs
IGMP querier timeout: 255 secs, configured value: 255 secs
IGMP unsolicited report interval: 10 secs
IGMP robustness variable: 2, configured value: 2
IGMP reporting for link-local groups: disabled
IGMP interface enable refcount: 1
IGMP interface immediate leave: disabled
IGMP VRF name default (id 1)
IGMP Report Policy: None
IGMP State Limit: None
IGMP interface statistics: (only non-zero values displayed)
General (sent/received):
v2-queries: 0/27, v2-reports: 0/580187, v2-leaves: 0/913
v3-queries: 16129/88823, v3-reports: 0/1049461
Errors:
Interface PIM DR: Yes
Interface vPC SVI: Yes
Interface vPC CFS statistics:
DR queries sent: 1
DR queries rcvd: 1
DR updates sent: 1
DR updates rcvd: 22

 

CORE-2# sh ip igmp interface vlan 819
IGMP Interfaces for VRF "default"
Vlan819, Interface status: protocol-up/link-up/admin-up
IP address: 172.30.19.2, IP subnet: 172.30.19.0/24
Active querier: 172.30.19.2, version: 3, next query sent in: 00:01:33
Membership count: 67
Old Membership count 0
IGMP version: 3, host version: 3
IGMP query interval: 125 secs, configured value: 125 secs
IGMP max response time: 10 secs, configured value: 10 secs
IGMP startup query interval: 31 secs, configured value: 31 secs
IGMP startup query count: 2
IGMP last member mrt: 1 secs
IGMP last member query count: 2
IGMP group timeout: 260 secs, configured value: 260 secs
IGMP querier timeout: 255 secs, configured value: 255 secs
IGMP unsolicited report interval: 10 secs
IGMP robustness variable: 2, configured value: 2
IGMP reporting for link-local groups: disabled
IGMP interface enable refcount: 1
IGMP interface immediate leave: disabled
IGMP VRF name default (id 1)
IGMP Report Policy: None
IGMP State Limit: None
IGMP interface statistics: (only non-zero values displayed)
General (sent/received):
v2-queries: 0/27, v2-reports: 0/841548, v2-leaves: 0/915
v3-queries: 55295/72729, v3-reports: 0/1276255
Errors:
Packets with Local IP as source: 0, Source subnet check failures: 0
Query from non-querier:16129
Interface PIM DR: vPC Peer
Interface vPC SVI: Yes
Interface vPC CFS statistics:
DR queries sent: 1
DR queries rcvd: 1
DR updates sent: 1
DR updates rcvd: 22

 

After a while in that weird state it converges and either .2 or .3 are seeing as the querier on both Nexus. It continues on that behavior all the time.

CORE-1# sh ip igmp interface vlan 819
IGMP Interfaces for VRF "default"
Vlan819, Interface status: protocol-up/link-up/admin-up
IP address: 172.30.19.3, IP subnet: 172.30.19.0/24
Active querier: 172.30.19.2, expires: 00:02:31, querier version: 3

CORE-2# sh ip igmp interface vlan 819
IGMP Interfaces for VRF "default"
Vlan819, Interface status: protocol-up/link-up/admin-up
IP address: 172.30.19.2, IP subnet: 172.30.19.0/24
Active querier: 172.30.19.2, version: 3, next query sent in: 00:00:23

 

What I am missing here? Is there any particular debug/log to understand why is this happening? 

 

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g748437
Level 1
Level 1

‎06-26-2023 12:57 PM

What the hell??

CORE-2# sh ip igmp snooping querier | inc 819
819 172.30.19.3 v3 00:03:16 port-channel4096
CORE-2# sh ip igmp interface vlan 819 | inc Active
Active querier: 172.30.19.2, version: 3, next query sent in: 00:00:43
CORE-2#

 

Shouldn't it be like CORE-1:

CORE-1# sh ip igmp snooping querier | inc 819
819 172.30.19.2 v3 00:03:40 port-channel4096
CORE-1# sh ip igmp interface vlan 819 | inc Active
Active querier: 172.30.19.2, expires: 00:03:43, querier version: 3
CORE-1#

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