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

Shankar shankarp5 at gmail.com
Wed Sep 17 05:40:10 EDT 2008


Hey

Check if the server is sending out any control protocol or routing
protocols or any other packet that you expect only a router to send. I
really dont know the list, but as you suggested there are few protocol
packets, observing which the L2 box assumes that there is a router on
the other end....

regards,
shankar


On Tue, Sep 16, 2008 at 6:24 PM, F J <ripprapp at hotmail.com> wrote:
> 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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