We have a 4507r that routes multicast at layer 2 because of our particular setup. We are sending multicasts of video streams to remote locations and to do the transport we are using a product called a ITU and it only transmits and doesnt have 2 way communication. It uses the rx as a tx on one side to be able to do 2 gbit instead of 1 but in one way only. So since we would never get a reply from a pear, then any multicast routing protocol would fail since nobody will ever send a join message. So the 4507r recieves a bunch of multicast streams that it then forwards to the ITU that then brings that to a 3750 a few km down the road which then sends it to devices who then forwards them on the cable plant there. That in a nut shell is what it does.
layer 2 multicast by default is broadcasted in the vlan. so to fix this issue in the 4507r I used the mac addess-table static command to manually point my multicast in the right direction. It looks like this:
mac address-table static 0100.5e02.020a vlan 100 interface gi3/2 gi3/4 Gi3/40
What that does is:
when I see 188.8.131.52 which when connverted to layer 2 it becomes 0100.5e02.020a in vlan 100 send to interfaces gi3/2 gi3/4 Gi3/40
This works fantastic in the 4507r. The problems I encountered was with the 3750 a few km down the road. now this guy receieves only and never will send me any traffic since the ITU the is rx only. So it recieves about 720mb of multicast then when I try to direct the traffic properly like I did in the 4507r in the 3750 it detects that the input traffic from the ITU interface is not braodcast but multicast because in a show interface I see example Received 3706088870 broadcasts (3706051178 multicasts) but then when I tell it to send it only to this and that interfaces in the vlan, the switch ignores my command and broadcasts the traffic in the whole vlan which is causing me to over subscribe on my devices connected to it. They cant recieve 720mb of data
Problem number 2. when I turn on port number 2 on the ITU, the switch detects a loop and disables the interface. So I cant bring it up.
So here is the details of my switches ios version and switch models:
Well, that's a complicated description :) But you have a complicated situation, no doubt.
I just wonder here: You have the IGMP snooping disabled on the VLAN 100 on your 3750 switch. Why? If the subscribers are directly connected to it then the 3750 should be able to hear the IGMP joins and direct the multicast traffic appropriately to the subscribing ports only.
By the way, you do not need to have the multicast routing activated on your switches. What you are doing is only Layer2 switching of multicasts, not routing. I suggest turning it off by "no ip multicast-routing distributed".
well i turned off igmp snooping since nobody will ever send a join. and no one is connected to the 3750. in the 3750 which recieved multicasts from the 4507 I have a bunch of SEM devices which are devices which listens to a multicast then formats that for a cable network and shoots it in the network for setup boxes to pick up and display on the clients TV.
As for turning off multicast routing i guess would do no harm because indeed im doing layer 2 multicast. But why is the 3750 not doing the layer 2 multicast and instead broadcasts it in all the VLAN?
Here are some outlines: when the 3750 recieve the Multicast traffic from the ITU, then you could prevent the unnecessary ports on vlan 100 from recieving those multicast packet by applying the following command on it:
switchport block multicast
Problem number 2: to which port the second ITU port connected to? Is it to another port in the 4507?
If so, then the ITU would act as normal bridge that forwards BPDUs , Multicast and broadcast, and this is the correct behaviour, what you need to do is try to have layer-2 Ether channel (Port channel) between 2 ports on the 4507 and 2 ports on the 3750. This would allow you to have STP treat both ports as one single port and prevent it from blocking one.
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