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dialsc's avatar
dialsc
Guide
Nov 24, 2016

IGMP/MLD version incompatibility between M5300 switches

Hi all,   I'm facing a strange problem and start to think that this is a firmware issue. But as I'm not 100% sure if I got all the concepts/RFCs right, I might also be wrong so I decided to start t...
Firmware
Installation
Troubleshooting
dialsc's avatar
dialsc
Guide
Nov 26, 2016

Hi Daniel,

 

Thanks for taking care about this one. Here are the answers to your questions:

 

1) I hope I got the question right. Is your question related to having IGMP/MLD Snooping enabled on both, the access as well as the stack switch? If so, here's the answer. If not, please let me know... ;)

I've got IGMP/MLD Snooping enabled on both switches because of what I think I figured out. This is, if you do not have either of these two enabled, the M5300 is not forwarding multicast at all. At least I've seen a lot more problems regarding multicast not working as long as IGMP/MLD Snooping is not enabled on either one of the two switches. This is espacially true for IPv6 -> MLD. If I do not enable MLD Snooping, IPv6 traffic is not working propperly/reliable on the M5300 switches in general.

 

Furthermore, regarding the access switch I thought it might be exactly the right thing to enable IGMP/MLD Snooping on that switch because here I want the individual multicast traffic to only reach the end devices interessted in the individual multicast traffic.

 

2) No, I only want the stack switch do act as the IGMP/MLD querier. I guess you've seen that I also have VLANs configured for the IGMP and MLD Querier on the access switch. If you take another look you will also see that the querier role is not enabled on the access switch, neither for IGMP nor for MLD. I applied this configuration because of the following:

 

  • As I thought, the access switch is not acting as a querier for IGMP/MLD as long as these roles are disbabled in the configuration.
  • Having the VLANs configured in the IGMP/MLD Querier sections allows me to see which switch is currently being reckognized by the access switch as the querier. This is the main purpose of having the VLANs configured there.

Furthermore I think it behaves exactly like I thought it would. On the network itself - using Wireshark - I only see IGMP/MLD queries sent out by the stack switch.

 

---------------------------

 

Maybe the following explanation might be also useful to you. The scenario I'm talking about here is more ore less just an extract of our network. The stack switch described here is acctually acting as a distribution switch which and also as an area border router in our OSPF setup. Therefore I configured it to also be the MCast Router in the OSPF area it acts as the ABR for. This stack servs more than just one VLAN, as you've propperly seen already. I just wanted to make it as simple as possible when I started to describe the problem here and therefore I was just taking about one VLAN running over these two switches, especially the stack switch.

 

Given the fact that the stack switch acts as an ABR as well as the MCast Router for several VLANs in its area I thought it would make a lot of sence to also let this switch act as the IGMP and MLD querier so everything regarding OSPF, IGMP and MLD MCast Routing/Queriing runs at this switch.

 

I really hope this helps and if not, please let me know. I would be happy to help you as much as possible.

 

Best regards.

 

dialsc

Carl_z's avatar
Carl_z
NETGEAR Expert
Dec 01, 2016

Hi dialsc,

Here，I want to mention that for IGMPv3 and MLDv2 we need to check multicast tables via CLI.

I tried with your configuration on local, but can reproduce your issue.

The test result:

ipv4 sender

ipv4 sendser.png

ipv4 receiver

ipv4 receiver.png

 

ipv6 sender

ipv6 sender.png

ipv6 receiver

 

 

ipv6 receiver.png

 

multicast tables on switch

sw1 table.png

tables sw2.png

 

Also I will send your my configuration files via private message. Hope it helps for you.

Regards

Carl

Netgear Employee

 

 

 

 

 

 

  • dialsc's avatar
    dialsc
    Guide
    Dec 01, 2016

    Hi Carl,

     

    thank you very much for taking a look to this and your answer. I think the reason why it is working for you is because you applied the workaround I mentioned in my original post in your configuration as well. Here's the extract of the configuration you sent to me:

     

    interface vlan 48
    routing
    ip address 192.168.48.1 255.255.240.0
    ip ospf area 0.0.0.3
    ip ospf cost 10
    ipv6 address 2a02:120d:5033:c211::1/64
    ipv6 enable
    ipv6 nd managed-config-flag
    ipv6 nd other-config-flag
    ipv6 nd ra-interval 30 22
    ipv6 mld router
    ipv6 mld query-interval 30
    ipv6 mld version 1
    ipv6 pim
    ipv6 ospf area 0.0.0.3
    ipv6 ospf cost 10
    ip igmp
    ip igmp version 1
    ip pim
    exit

     

    If I'm not totally wrong you are running the IMGP querier in IGMP version 1 and the MLD Querier in MLD version 1. This is what I wront would work. BUT what does not work, at least for me, is to apply the following, the default versions on the MCR, the stacked switch which acts as the IGMP/MLD Querier (in your setting SW1):

     

    interface vlan 48
    routing
    ipv6 mld version 2
    ip igmp version 3

     

    Do you mind let it run with this settings and see what happens? I bet multicast is not working as it isn't for me.

     

    Best regards.

     

    dialsc

    • Carl_z's avatar
      Carl_z
      NETGEAR Expert
      Dec 02, 2016

      Hi dialsc ,

      In fact, the version used is mld v2 & igmp v3.   If it is mld v1 and igmp v1 ,it would not be able to learn igmpv3 table and mld v2 table （these tables can been shown via cli command "show igmpsnooping ssm entries  " &"show mldsnooping ssm entries"）

       

      The reasion why in the configuration files it showed "ip igmp version 1"&"ipv6 mld version 1" it that:

      At first I config with igmp v1 and mld v1,and saved . it turned to be no issue as your result.

      Then changed to igmp v3 and mld v3 ，here ,forgot to save:smileysad:，then download the configuration files and send to you.  So,in configuration files it is still igmp v3 and mld v1.

       

      I would save the configuration file and then send to you again，sorry for tis mistake.

       

      Regards

      Carl

      Netgear Employee

       

      • dialsc's avatar
        dialsc
        Guide
        Dec 02, 2016

        Hi Carl,

         

        I think I was able to make a little step towards getting things working. Let's seperate things into three areas which are:

         

        • IGMP
        • MLD
        • What is being shown in the WebUI

         

        IGMP:

        I was able to get things working by changing "Switching\Multicast\IGMP Snooping\Configuration\Validate IGMP IP header" to Disabled. Having Header Validation enabled, multicast - as of this test scenario - is not working. Do you mind giving us an idea why this is working having IGMP Header Validation disabled on the Access Switch? I ask because I really do not understand this, sorry?

         

        MLD:

        I'm very sorry but here at my installation this is still not working at all.

         

        What is being shown in the WebUI:

        I do not understand why this is not being shown in the WebUI. I would really expect these groups to be shown in the WebUI as well. This, by the way, is also true for all the other multicast group entries the switch isn't showing in the WebUI allthough they are registered and running. Could you please give me an idea where I could put this as a feature request?

         

        Thank you very much!

         

        Best regards.

         

        dialsc

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