IGMP snooping not working (video stream multicast r broadcasted to all switch ports)

[MustafaE2015]

Hello ,

I have a Cisco switch 3750 catalyst and connected to it i have :

- over 20 receivers (Dektec DVB-s2) each Multicasting to it a video stream (~42MBps each) by same Multicast IP but different port number. 

- 3 server (Tektronix Sentry video monitoring servers) that should each receive selected Multicast for monitoring. 

I noticed that all multicast streams received by the switch are bridged to all of its ports causing the switch to flood with traffic.

As far as I understand the switch should not do that but rather send the multicast to members that are requesting it by some sort 

of multicast grouping protocol. Why is it broadcasting to all ports ? . kindly note that all devices connected to switch support IGMP v2.

Please advice ? 

[Anthony Brandelli]

Is IGMP snooping enabled?

sh ip igmp snooping

[MustafaE2015]

Thank you Anthony  for your reply ,

Yes it is  , I'm not a Cisco expert , but I used Cisco Network Assistant (CNA) and checked the box saying enable IGMP snooping and enabled immediate leave and PIM learning method. 

And to solve the congestion I manually created a Multicast-group , but I want the switch to create it dynamically - if I understand correctly IGMP should be doing that.

Thank you for your help

[Anthony Brandelli]

In CNA does it indicate "enabled" under the status column beside the appropriate VLAN this traffic is on? 

The learning mode is almost always pim-dvmrp, the other option is CGMP which isn't really used anymore (or never really was...)

IGMP snooping works for end hosts so that only receivers who indicate they want the multicast traffic will get it, which is what you are looking for. The host sends a membership report which the switch sees and then adds that port to the group. 

[MustafaE2015]

I'm not sure , i didn't note that , I assumed it would be since I applied the new settings.

I have no access to the switch at the moment but assuming it was not actually enabled, what could this mean ? is it possbile that my switch does'nt support it.

I had a look at below link to check if it is , but  since I'm new to this it only confused me : )

http://www.cisco.com/c/en/us/support/docs/ip/ip-multicast/29480-167.html#req

[Anthony Brandelli]

It might just be as simple as somehow it's been disabled on that particular VLAN. If you have SSH access you can run the show command above as well, to double check that CNA is correct. 

That matrix is saying that for the 3750 series IGMP snooping is supported in all IOS versions, and that it should be enabled by default on all VLANs (globally). 

[MustafaE2015]

Unfortunately I don't have a SSH access , but I try it as soon as I get my hands on the system and let you know how it goes.

I noticed on one of the matrix titled "IGMP snooping features" that it says that my switch doesn't support ip IGMP snooping ? any idea what this mean ?

sorry about the too many questions 

[Anthony Brandelli]

For the 3750 series I see support for everything that you need, the only thing it doesn't support is full CGMP which you don't need. IGMP snooping is a pretty basic feature and is supported on basically anything, you'll even find this feature in cheap SMB switches a lot of the times. 

Let us know what is revealed when you have access to the switch. 

[MustafaE2015]

Duly noted 

Thank you very much Anthony for your help,

Much appreciated,

[MustafaE2015]

Update :

Hi Anthony ,

The problem was solved by this command :

# ip igmp snooping querier enable

Thanks again for your help