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

Mike Louis MLouis at nwnit.com
Tue Sep 16 08:10:44 EDT 2008


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<mailto: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<http://239.1.1.1/>       10.21.65.5<http://10.21.65.5/>      14
    239.1.1.2<http://239.1.1.2/>       10.21.65.5<http://10.21.65.5/>      10
    228.0.198.75<http://228.0.198.75/>    10.21.64.4<http://10.21.64.4/>      25
    228.0.198.76<http://228.0.198.76/>    10.21.64.4<http://10.21.64.4/>      13
    228.0.198.77<http://228.0.198.77/>    10.21.64.4<http://10.21.64.4/>      13
    5 Incoming multicast streams

    Port   Host            Subscribed        Age
    19     10.21.64.2<http://10.21.64.2/>      225.10.10.10<http://225.10.10.10/>      66
    19     10.21.64.2<http://10.21.64.2/>      226.10.10.10<http://226.10.10.10/>      63
    20     10.21.64.3<http://10.21.64.3/>      224.2.127.254<http://224.2.127.254/>     67
    20     10.21.64.3<http://10.21.64.3/>      224.2.127.255<http://224.2.127.255/>     69
    20     10.21.64.3<http://10.21.64.3/>      234.5.6.7<http://234.5.6.7/>         63
    20     10.21.64.3<http://10.21.64.3/>      239.1.1.1<http://239.1.1.1/>         64
    20     10.21.64.3<http://10.21.64.3/>      239.1.1.2<http://239.1.1.2/>         61
    21     10.21.64.4<http://10.21.64.4/>      228.0.198.75<http://228.0.198.75/>      68
    21     10.21.64.4<http://10.21.64.4/>      228.0.198.76<http://228.0.198.76/>      63
    21     10.21.64.4<http://10.21.64.4/>      228.0.198.77<http://228.0.198.77/>      60
    21     10.21.64.4<http://10.21.64.4/>      All Groups        69
    45     10.21.64.1<http://10.21.64.1/>      All Groups        1


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