2

I have multicast hosts that keep leaving a group, only to join back up which results in loss of video feeds.

The network consists of a variety of Cisco 2960's and a Cisco 9300 w/ PIM Sparse mode set on the VLAN interface (this handles the IGMP snooping querier task, I've tried it without PIM and enabled the querier but I had the same result). IGMP snooping is enabled on every switch, and at each switch the ip igmp snooping groups / querier / mrouter all display the right groups and the right ports. The issues I am having are all on a single VLAN.

My biggest issue seems to be that I am unable to find out what the following IGMP debugging information means, of note, I am not seeing any of these leave requests on the 9300, just the 2960 that the host(s) are connected to..also, port 10 is what the host was connected to, it also happens to hosts on other ports:

Jul 31 12:29:27.137 EST: IGMPSN: timer: Vlan X report timer expired
Jul 31 12:29:27.137 EST: IGMPSN: sync group for Vlan X robustness variable 2
Jul 31 12:29:27.137 EST: IGMPSN: sync group for Vlan X GCE 0100.5eMAC
Jul 31 12:29:27.137 EST: IGMPSN: sync group for group (224.16.17.23) blist (1)
Jul 31 12:29:27.137 EST: IGMPSN: group (224.16.17.23): has v2 Hosts
Jul 31 12:29:27.137 EST: IGMPSN: group (224.16.17.23): [0]GQ-miss-list members are:IGMPSN: group: Gi1/0/10,
Jul 31 12:29:27.137 EST: IGMPSN: group (224.16.17.23): [1]GQ-miss-list members are:IGMPSN: group: Gi1/0/10,
Jul 31 12:29:27.137 EST: IGMPSN: group (224.16.17.23): [2]GQ-miss-list members are:
Jul 31 12:29:27.137 EST: IGMPSN: mgt: Vlan X gce 0100.5e.MAC remove port Gi1/0/10
Jul 31 12:29:27.137 EST: IGMPSN: group: Deleting port Gi1/0/10 from group 224.16.17.23 on Vlan X
Jul 31 12:29:27.137 EST: IGMPSN: sync group for Vlan X GCE 0100.5eMAC

REPEAT FOR EVERY OTHER GROUP THE HOSTS ARE MEMBERS OF

Jul 31 12:29:35.026 EST: IGMPSN: Received IGMP Leave for group 224.16.17.23 received on Vlan X, port Gi1/0/10
Jul 31 12:29:35.026 EST: IGMPSN: group: Leave for group 224.16.17.44 from Client X.X.X.50 received on Vlan X, port Gi1/0/10, mvr group (No)
Jul 31 12:29:35.026 EST: IGMPSN: group: Adding client ip X.X.X.50, port_id Gi1/0/10, on vlan X
Jul 31 12:29:35.026 EST: IGMPSN: MCAST IP address 224.16.17.23, MAC address 0100.5e.MAC
Jul 31 12:29:35.026 EST: IGMPSN:  Locate gce 0100.5e.MAC, on Vlan X
Jul 31 12:29:35.026 EST: IGMPSN:  locate group 224.16.17.23, on Vlan X
Jul 31 12:29:35.043 EST: IGMPSN: Received IGMPv2 Report for group 224.16.17.23 received on Vlan X, port Gi1/0/10
Jul 31 12:29:35.043 EST: IGMPSN: group: Received IGMPv2 report for group 224.16.17.23 from Client X.X.X.50 received on Vlan X, port Gi1/0/10
Jul 31 12:29:35.043 EST: IGMPSN: group: Skip client info adding - ip X.X.X.50, port_id Gi1/0/10, on vlan X
Jul 31 12:29:35.043 EST: IGMPSN: MCAST IP address 224.16.17.23, MAC address 0100.5e.MAC
Jul 31 12:29:35.043 EST: IGMPSN:  Locate gce 0100.5e.MAC, on Vlan X
Jul 31 12:29:35.043 EST: IGMPSN:  locate group 224.16.17.23, on Vlan X
Jul 31 12:29:35.043 EST: IGMPSN: Add v2 group 224.16.17.23 member port Gi1/0/10, on Vlan X
Jul 31 12:29:35.043 EST: IGMPSN: mgt: Vlan X gce 0100.5e.MAC add port Gi1/0/10
Jul 31 12:29:35.043 EST: L2MM: setting Gi1/0/10 in gce->mbr_blist
Jul 31 12:29:35.043 EST: IGMPSN: group: Added port Gi1/0/10 to group 224.16.17.23
Jul 31 12:29:35.043 EST: l2mcsn_process_report: TIMER_START for group 15.75.73.224 for time 10000 * 100
Jul 31 12:29:35.043 EST: IGMPSN: group: Forwarding 224.16.17.23 report to router ports

REPEAT FOR ALL GROUPS

So, "GQ-miss-list members are" must be general query miss list..but if only one host needs to respond to a general query, what is this miss list? Why does it seem to be getting my hosts deleted from the group? And, how can I stop it! I

Thanks in advance for the assist!

6
  • First, you are using a RESERVED IPv4 multicast address, and you should not do that. Probably, you want to use something in the Organization-Local scope (239.0.0.0/8).
    – Ron Maupin
    Aug 4 '20 at 21:37
  • 1
    Next, the LEAVE request is sent by the host, so there is something on the host that is leaving the IGMP group. Also, do you have an mrouter port on both switches? See this answer for an explanation from Cisco.
    – Ron Maupin
    Aug 4 '20 at 21:54
  • I will change the multicast range. I have not statically assigned mrouter ports, but they have dynamically learned them. With regards to the leave statements, I understand the host is supposed to send it, but, the only time I see the host leave requests are when they are listed in the GQ-miss-list member
    – Rnet
    Aug 4 '20 at 22:08
  • The leave message is in the debug information you have in the last set of messages: Jul 31 12:29:35.026 EST: IGMPSN: Received IGMP Leave for group 224.16.17.23 received on Vlan X, port Gi1/0/10 and Jul 31 12:29:35.026 EST: IGMPSN: group: Leave for group 224.16.17.44 from Client X.X.X.50 received on Vlan X, port Gi1/0/10, mvr group (No) The second message is clear that it was received from the host.
    – Ron Maupin
    Aug 4 '20 at 22:11
  • Unfortunately, we cannot help you with the host. You could try to ask about why it is leaving on Server Fault.
    – Ron Maupin
    Aug 4 '20 at 22:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.