[e-nsp] Summit450X - strange IGMP-snooping on port connected to Linux server?

Tue Sep 16 08:54:47 EDT 2008

Hi,
I am running a Juniper M10 as Multicast router in my network. It automatically becomes the DR of the "VLAN" as the Linux server is situated on. I also have other Linux servers on that switch in the same VLAN and IGMP-snooping is working for them. 

They are running RedHat and not Suse though. They are not listed as "Router" by the Summit450X.

When doing a tcpdump on my Linux server I do not see any traffic going to 224.0.0.2 (all routers) so I don't understand why the switch lists that Linux as a router. Really strange...

BR
/// Fredrik

From: MLouis at nwnit.com
To: fabian.extr at gmail.com; extreme-nsp at puck.nether.net
Date: Tue, 16 Sep 2008 08:10:44 -0400
Subject: Re: [e-nsp] Summit450X - strange IGMP-snooping on port connected	to	Linux server?

In my experience, IGMP snooping will not work unless the layer 2 switch snoops the client report. Meaning you have to have clients who want to join a group sending IGMP join reports that the switch
 can snoop. This usually requires that something be performing the quierier process, ie a multicast enabled router. 224.0.0.2 is all routers MC address. Enable PIM on the router and see if IGMP snooping works.

From: extreme-nsp-bounces at puck.nether.net [extreme-nsp-bounces at puck.nether.net] On Behalf Of Fabian [fabian.extr at gmail.com]

Sent: Tuesday, September 16, 2008 7:28 AM

To: extreme-nsp at puck.nether.net

Subject: Re: [e-nsp] Summit450X - strange IGMP-snooping on port connected to Linux server?

Hi Frederik,

If your server is considered as a Router, that means that it is advertising on multicast address :
224.0.0.2

So do a TCPDUMP to check if so and verify if you don’t have a router feature enabled.

Regards, Fabian.

From: extreme-nsp-bounces at puck.nether.net [mailto:extreme-nsp-bounces at puck.nether.net]
On Behalf Of F J

Sent: mardi 16 septembre 2008 12:26

To: extreme-nsp at puck.nether.net

Subject: Re: [e-nsp] Summit450X - strange IGMP-snooping on port connected to Linux server?

Hi,

Thanks for your answer. But isn't the BCR and CBSR config only important if 

you are running the Switch in layer3?

I am only using it as a layer2 switch.

I still think that it is strange that the switch is considering this server as being

a "router" when running the show commands. There must be some critera for

the switch to do that or? 

More info about this Linux server:

My Linux server is running JBoss and I see some IGMP-join packages to going to

224.0.0.75 and 228.30.4.76 when starting up.

Best Regards

/// Fredrik

Date: Tue, 16 Sep 2008 11:52:02 +0300

From: napstertash at gmail.com

To: ripprapp at hotmail.com

Subject: Re: [e-nsp] Summit450X - strange IGMP-snooping on port connected to Linux server?

CC: extreme-nsp at puck.nether.net

Hello FJ,

On Tue, Sep 16, 2008 at 8:21 AM, F J <ripprapp at hotmail.com> wrote:

Hi,

I am using a Summit450X as a layer2 switch in my multicast network. 

I am using PIM SM on my routers and I am running IGMP snooping on my layer2 switches.

On this 450X-switch I have a HP server runnning Linux connected to port 21.

When running some show commands (see below) it looks like the switch thinks that the

server is a router? And that it should get all Multicast streams? 

You might have to play a lot more with the priorities so you figure this out, I would think. 

Can anyone explain what is causing this? 

I think the answer might be between the configuration settings you have got for both the BSR and CBSR.

Is my switch misconfigured or is my server doing something strange?

What is the criteria for being listed as a router by the switch?

Port 45 is connected to the closest router.

Any ideas of what could be causing this kind of behaviour is appreciated!

If you don't want this box to participate the the multicast traffic then I would suggest you remove that port form the selected list, OR make the specified port that you
 want to be the BSR by using the priorities.

Hope it helps.

Regards

Best Regards

Fredrik

X450a-48tdc.19 # sh igmp snooping 

Vlan             Vid  Port   #Senders #Receivers Router Enable

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

SN102          164         6                          Yes 

                      19               2         No

                      20               5         No

                      21               3         Yes

                      45               0         Yes

VLAN SN102          (164) Snooping=Enabled  

    Group           Sender          Age  

    239.1.1.1       
10.21.65.5      14   

    239.1.1.2       
10.21.65.5      10   

    228.0.198.75    
10.21.64.4      25   

    228.0.198.76    
10.21.64.4      13   

    228.0.198.77    
10.21.64.4      13   

    5 Incoming multicast streams 

    Port   Host            Subscribed        Age    

    19     10.21.64.2      
225.10.10.10      66     

    19     10.21.64.2      
226.10.10.10      63     

    20     10.21.64.3      
224.2.127.254     67     

    20     10.21.64.3      
224.2.127.255     69     

    20     10.21.64.3      
234.5.6.7         63     

    20     10.21.64.3      
239.1.1.1         64     

    20     10.21.64.3      
239.1.1.2         61     

    21     10.21.64.4      
228.0.198.75      68     

    21     10.21.64.4      
228.0.198.76      63     

    21     10.21.64.4      
228.0.198.77      60     

    21     10.21.64.4      All Groups        69    

    45     10.21.64.1      All Groups        1     

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