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 this thread. Let me try to explain it as simple as possible: 1 MCast Router, hence being called MCR.This one is a stack of one M5300-28G3 and one M5300-28GF3 switch. It akts as the IGMP and MLD querier as well as the MCast Router for IPv4 and IPv61 Access Switch serving an office, hence being called OAS.This one is a M5300-28G-PoE+ running in Layer 2+ mode and having end devices connected to it.What I see is a strange problem with IPv4 based multicast traffic as well as IPv6 based multicast traffic, especially with the IGMP/MLD Snooping at OAS. Before I go into the details, here's a short overview of the "test setup". OAS is connected to MCF via a LAGTwo Windows 10 clients are connected to the OASGot a test VLAN, VLAN10, configured at all switches to work propperly and the Windows clients are put into this VLAN. So everything runs in that VLAN regarding this test setup.On the MCF, under "Routing/Multicast/IGMP/Routing Interface Configuration/VLAN" VLAN10 is enabled and the version is set to V3.On the OAS, under "Switching/Multicast/IGMP Snooping" IGMP Snooping is enabled for VLAN10 and the LAG to the MCF is configured as Multicast Router Port.Having a multicast test application running on both Windows clients, one as sender and one as receiver, the MCast group is 239.1.2.3Okay, that's the setup. Problem number 1 is the following: The multicast group being used is not being reckognized by the OAS. It is not available at the MFDB .The multicast traffice is not being forwarded from the sender to the receiver by the OAS.Strange enough, in the WebUI under "Switching/Multicast/IGMP Snooping/Querier VLAN Configuration" I can see that the MCF is being shown as the current active querier on VLAN10 and it is also bein shown that it is using IGMP version3. Even more strange, IGMP V3 is the default setting on the M5300 under Router/Multicast/... So in short words: Multicsat is not working having this setup. ------------------------------ Problem number 2: The second problem is exactly the same thing as problem number one. Same setup, same test procedure, same result. The only difference is that it is related to IPv6, thus Routing/IPv6 Multicast/MLD and Switching/Multicast/MLD Snooping. Furthermore the version not working here is V2 which is also the default on the M5300 as MCast Router. For MLD I have to change the verison to V1 in order to get things starting to work. ------------------------------- Workaround for both problems: Both problems can be addressed/workarounded (does this word exist?) by changing the IMGP/MLD Querier to one lower version on the MCR -> IGMP Querier to version 2 and MLD Querier to version 1. As soon as I do this, everything's starting to work. ------------------------------- Okay, that's it. To me this looks like a serios bug in the IGMP/MLD Snooping routines of the M5300 firmware. Would someone agree on this or is it me missing some fundamental know how? Best regards. dialsc

Hi dialsc Thank you for the thorough description of your issue above. At this stage our Engineering team is tentatively reproducing your setup on M5300 Managed switches and we will get back to you shortly. Let me tell you that RFC 3376 expects some limitations in Multicast Router behavior: for instance in 7.3.1 section we show that if ANY older version of IGMP are present on routers, the querier MUST use the lowest version of IGMP present on the network. But again thank you for the details, we are checking the real behavior on M5300 as I speak. Regards,

Hi Laurent, Thank you for your answer. Please note that I would be happy to support your engineers with what-ever I can, just let me know. Regarding chapter 7.3.1 of RFC 3376. As I understand it, it describs how the Multicast Router should handle different versions of IGMP. The problem I'm facing seems to be the other way around to me. It's not the Multicast Router having problems but the Layer 2 switch's IGMP Snooping which does not work if the MCast Router sends out IGMP Queries in version 3. In fact, at least for IPv4, the multicast group is being listed in the MCast Table at the MCast Router (Routing/Multicast) as soon as the Multicast sender starts to send and eventhough this entry is missing on the Access Switch's MFDB. This by the way does not apply to IPv6 multicast. This one is very interessting. The MCast Table of the Multicast Router is always empty. There is never ever a single entry available regardless of what version of MLD is being used by the querier. This - by the way - looks to me to be another strang thing on the M5300. But again, let me know how I can help, pls. Best regards, dialsc

Hi dialsc On behalf of our Engineering team: We have setup the same environment as yours and everything works correctly no matter which version of IGMP/MLD. The behavior is correct between Mrouter and Querier on M5300: we can test all V1/V2/V3 version on IGMP and V1/V2 on MLD using traffic generator. Could you please send the multicast application name and version to us which is used on your MS Windows PCs? Such as: VLC Version: 2.2.4.0 Otherwise ,The configuration file will also help us to resolve your concern. Please following this guide to send it to us. How do I send diagnostic files from my Managed Switch to NETGEAR community moderators Regards,

Hi Laurent, Thanks again. This pic looks different from my setup. Give me a moment to grap together all the files. I will send it out to the email address described soon. The application to test multicast I use is called MultiCastor 3.0. I will add it in a zipped form to the email, thus it contains the config I'm running for the sender. The receiver can be simulated using the same tool listening to the according multicast groups. Greez, dialsc

Thank you. Please also send the Application name, version number and all relevant information on your software application generating multicast traffic. Laurent

Forum Discussion

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 this thread. Let me try to explain it as simple as possible:

1 MCast Router, hence being called MCR.
This one is a stack of one M5300-28G3 and one M5300-28GF3 switch. It akts as the IGMP and MLD querier as well as the MCast Router for IPv4 and IPv6
1 Access Switch serving an office, hence being called OAS.
This one is a M5300-28G-PoE+ running in Layer 2+ mode and having end devices connected to it.

What I see is a strange problem with IPv4 based multicast traffic as well as IPv6 based multicast traffic, especially with the IGMP/MLD Snooping at OAS. Before I go into the details, here's a short overview of the "test setup".

OAS is connected to MCF via a LAG
Two Windows 10 clients are connected to the OAS
Got a test VLAN, VLAN10, configured at all switches to work propperly and the Windows clients are put into this VLAN. So everything runs in that VLAN regarding this test setup.
On the MCF, under "Routing/Multicast/IGMP/Routing Interface Configuration/VLAN" VLAN10 is enabled and the version is set to V3.
On the OAS, under "Switching/Multicast/IGMP Snooping" IGMP Snooping is enabled for VLAN10 and the LAG to the MCF is configured as Multicast Router Port.
Having a multicast test application running on both Windows clients, one as sender and one as receiver, the MCast group is 239.1.2.3

Okay, that's the setup. Problem number 1 is the following:

The multicast group being used is not being reckognized by the OAS. It is not available at the MFDB .
The multicast traffice is not being forwarded from the sender to the receiver by the OAS.

Strange enough, in the WebUI under "Switching/Multicast/IGMP Snooping/Querier VLAN Configuration" I can see that the MCF is being shown as the current active querier on VLAN10 and it is also bein shown that it is using IGMP version3.

Even more strange, IGMP V3 is the default setting on the M5300 under Router/Multicast/...

So in short words: Multicsat is not working having this setup.

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

Problem number 2:

The second problem is exactly the same thing as problem number one. Same setup, same test procedure, same result. The only difference is that it is related to IPv6, thus Routing/IPv6 Multicast/MLD and Switching/Multicast/MLD Snooping. Furthermore the version not working here is V2 which is also the default on the M5300 as MCast Router. For MLD I have to change the verison to V1 in order to get things starting to work.

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

Workaround for both problems:

Both problems can be addressed/workarounded (does this word exist?) by changing the IMGP/MLD Querier to one lower version on the MCR -> IGMP Querier to version 2 and MLD Querier to version 1. As soon as I do this, everything's starting to work.

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

Okay, that's it. To me this looks like a serios bug in the IGMP/MLD Snooping routines of the M5300 firmware. Would someone agree on this or is it me missing some fundamental know how?

Best regards.

dialsc

Firmware

Installation

Troubleshooting

28 Replies

LaurentMa
NETGEAR Expert
Nov 25, 2016
Hi dialsc

Thank you for the thorough description of your issue above.

At this stage our Engineering team is tentatively reproducing your setup on M5300 Managed switches and we will get back to you shortly.

Let me tell you that RFC 3376 expects some limitations in Multicast Router behavior: for instance in 7.3.1 section we show that if ANY older version of IGMP are present on routers, the querier MUST use the lowest version of IGMP present on the network. But again thank you for the details, we are checking the real behavior on M5300 as I speak.

Regards,
- dialsc
  Guide
  Nov 25, 2016
  Hi Laurent,
  
  Thank you for your answer. Please note that I would be happy to support your engineers with what-ever I can, just let me know.
  
  Regarding chapter 7.3.1 of RFC 3376. As I understand it, it describs how the Multicast Router should handle different versions of IGMP. The problem I'm facing seems to be the other way around to me. It's not the Multicast Router having problems but the Layer 2 switch's IGMP Snooping which does not work if the MCast Router sends out IGMP Queries in version 3. In fact, at least for IPv4, the multicast group is being listed in the MCast Table at the MCast Router (Routing/Multicast) as soon as the Multicast sender starts to send and eventhough this entry is missing on the Access Switch's MFDB.
  
  This by the way does not apply to IPv6 multicast. This one is very interessting. The MCast Table of the Multicast Router is always empty. There is never ever a single entry available regardless of what version of MLD is being used by the querier. This - by the way - looks to me to be another strang thing on the M5300.
  
  But again, let me know how I can help, pls.
  
  Best regards,
  
  dialsc
  - LaurentMa
    NETGEAR Expert
    Nov 25, 2016
    Hi dialsc
    
    On behalf of our Engineering team:
    
    We have setup the same environment as yours and everything works correctly no matter which version of IGMP/MLD.
    
    The behavior is correct between Mrouter and Querier on M5300: we can test all V1/V2/V3 version on IGMP and V1/V2 on MLD using traffic generator.
    
    Could you please send the multicast application name and version to us which is used on your MS Windows PCs?
    
    Such as:
    
    VLC
    
    Version: 2.2.4.0
    
    Otherwise ,The configuration file will also help us to resolve your concern.
    
    Please following this guide to send it to us.
    
    How do I send diagnostic files from my Managed Switch to NETGEAR community moderators
    
    Regards,
DanielZhang
NETGEAR Expert
Nov 26, 2016
Hi dialsc,
Thanks for your information.
We had receive the diagnostic file you send to us.
The configuration and application information are very useful to us.
We will analyze and reproduce the same scenario just like yours.

So Please use the work around solution just now before we trigger out your concern.

BTW, I also have two question for you.
1) Did you want to limit IGMP/MLD report&query traffic on access switch or stack？
It means that the Multicast Router will collect all report packets in special VLAN then forward out on enabled port.
Any other port will not receive report packets send by other client.

2) Did you want to deploy the IGMP/MLD L3 and L2 querier both on Stackand access switch？
That will confuse the client that two query packets send with different IGMP/MLD version at the same time.
Also the version of L2 querier only support V1/V2 but the L3 querier support V1/V2/V3.
normally there should be only one querier in same VLAN and same device.
but different device maybe have two or more querier in same VLAN.

Regards,
Daniel.
- 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
    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 receiver
    
    ipv6 sender
    
    ipv6 receiver
    
    multicast tables on switch
    
    Also I will send your my configuration files via private message. Hope it helps for you.
    
    Regards
    
    Carl
    
    Netgear Employee