Hi, I'm thinking this is something simple, but I'm not very familiar with the configuration of Cisco switches / routers.
Can somebody tell me how I can get my Catalyst 3750 switch to not broadcast multicast data to all ports? I have a really simple switch setup. All ports are on the same VLAN and are connected to devices with IP's on the same subnet. There is a router attached to one port, but no multicast data needs to flow through it.
I spent a couple hours digging around today trying to figure this out but without any luck. I verified IGMP snooping is enabled on the Catalyst and on my VLAN. Since all my ports are connected directly to PC type devices, I turned on support for IGMP v2 immediate leave requests. From what I see when I type show ip igmp groups, I can see the switch is aware of what ports it has gotten IGMP group join requests from. The problem is that it doesn't seem to use that information to intelligently distribute multicast data. I'm seeing the data on ports that are not listed as being part of the group.
I found one post where a guy said he needed to attach a router to the switch that had multicast routing enabled in order for the multicast data not to broadcast. Another post said if all the multicast is just on one VLAN then no router is needed. I tried enabling multicast routing on the router I have, but it didn't seem to help, but I may not have set it up correctly.
Also one other thing I notice with this switch is the interfaces can take up to 10 seconds or so to become active after being plugged in. What would this be caused from? I'm guessing its trying to detect things out about the link that don't matter in my setup.
which groups? some of the low numbered ones such as 224.0.0.1 are used for signalling, and will always propagate.
the switch will only be managing the underlying multicast MAC addresses, and there are only 2^23 of those, so several IP multicast addresses use the same multicast. eg 224.0.0.1 and 225.0.0.1 use the same multicast MAC. if you use the related IP multicasts, allowing 1 thru a port amy allow the others.
i think you will need a router to do IGMP snooping, since this is all about using the device to router signalling to selectively flood the multicasts.
Another post said if all the multicast is just
well, multicast is working - you are just trying to cut down background traffic.
you should step back and decide if you even care about optimising away some multicast traffic - is the traffic in 100s packet / sec or Mbps?
I was initially testing with 239.192.0.1, but was unsure if that was an okay address to use. I then saw a post with somebody who said to use 224.1.2.3 to avoid mac address problems -- so that was the most recent one I was testing with.
Ok. I guess I'll have to read up more on how to configure the 7206VXR router for multicast. Yesterday I just got as far as enabling multicast-routing on the interface connected to the Catalyst switch and setting ip pim sparse-dense-mode. It didn't seem to help with the broadcasting to all ports issue.
needed. I tried enabling multicast
yea, it's pretty important to optimize if I want to use multicast. data could be 100's of Mbps to a multicast group. it's all for a LAN that I use to test IP video on. right now i'm just doing a single multicast group that's broadcasting 242 Mbps to everybody.
PIM should do it (PIM v2 if you have any non cisco gear that may need to connect) - it will be running dense mode unless you set up an RP and BSR (which you dont need).
worth checking if you have IGMP running on the LAN facing the multicast subnet.
I thought I got everything setup right, but still multicast data is broadcast to all ports. Can somebody give any input based on the cmd dumps pasted below?
the .3 subnet is the only one i care about having multicast traffic on My 7206VXR router is 192.168.3.1 and 192.168.2.1 The Catalyst 3750 is 192.168.3.5
I believe I have multicast routing enabled correctly on the router, with PIM set to sparse-dense on the 2 interfaces I use. IGMP / snooping is enabled on the switch as well. I see they both the switch / router detect each other. Is it correct for the Catalyst to be set as the designated multicast router? From the output to it looks like the Catalyst actually supports more than IGMP snooping. Maybe I don't need to enable IGMP / multicast routing on the 7206?
lab>show ip igmp interface FastEthernet3/0 is up, line protocol is up Internet address is 192.168.2.1/24 IGMP is enabled on interface Current IGMP version is 2 CGMP is disabled on interface IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Inbound IGMP access group is not set IGMP activity: 1 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 192.168.2.1 (this system) IGMP querying router is 192.168.2.1 (this system) No multicast groups joined FastEthernet3/1 is up, line protocol is up Internet address is 192.168.3.1/24 IGMP is enabled on interface Current IGMP version is 2 CGMP is disabled on interface IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Inbound IGMP access group is not set IGMP activity: 2 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 192.168.3.5 IGMP querying router is 192.168.3.1 (this system) Multicast groups joined (number of users): 224.0.1.40(1)
lab>show ip pim interface
Address Interface Version/Mode Nbr Query DR Count Intvl
catalyst>show ip igmp interface Vlan1 is up, line protocol is up Internet address is 192.168.3.5/24 IGMP is enabled on interface Current IGMP host version is 2 Current IGMP router version is 2 IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Last member query count is 2 Last member query response interval is 1000 ms Inbound IGMP access group is not set IGMP activity: 2 joins, 0 leaves Multicast routing is enabled on interface Multicast TTL threshold is 0 Multicast designated router (DR) is 192.168.3.5 (this system) IGMP querying router is 192.168.3.1 Multicast groups joined by this system (number of users): 224.0.1.40(1)
catalyst>show ip igmp snooping vlan 1 Global IGMP Snooping configuration:
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