Hi,
I have a VDSL2 connection from my ISP, with IPTV. I have a STB (set-top box) connected to a Cisco SLM2008, and this is connected to my VDSL2-router. The SLM2008 is set up with port-mirroring on the port between the SLM2008 and the VDSL2-router, in addition to a tcpdump running on the router.
IPs:
STB - 192.168.10.107
SLM2008 - 192.168.10.3
Router - 192.168.10.1
At the SLM2008, I have turned off every IGMP-feature. I then turn on the STB, switch a channel and watch the IGMP-traffic on the mirror-port on the switch and on the port on the router:
# The mirror-port on the switch:
14:29:26.067051 IP 192.168.10.107 > 233.171.129.74: igmp v2 report 233.171.129.74
14:29:30.606737 IP 192.168.10.107 > 224.0.0.2: igmp leave 233.171.129.74
14:29:30.779215 IP 192.168.10.107 > 233.171.129.94: igmp v2 report 233.171.129.94
14:29:33.780563 IP 192.168.10.107 > 233.171.129.94: igmp v2 report 233.171.129.94
14:30:08.125431 IP 192.168.10.1 > 224.0.0.1: igmp query v2
14:30:11.697049 IP 192.168.10.107 > 233.171.129.255: igmp v2 report 233.171.129.255
14:30:16.043599 IP 192.168.10.107 > 233.171.129.94: igmp v2 report 233.171.129.94
# The port on the router:
14:29:24.076640 IP 192.168.10.107 > 233.171.129.74: igmp v2 report 233.171.129.74
14:29:28.616291 IP 192.168.10.107 > 224.0.0.2: igmp leave 233.171.129.74
14:29:28.788789 IP 192.168.10.107 > 233.171.129.94: igmp v2 report 233.171.129.94
14:29:31.790075 IP 192.168.10.107 > 233.171.129.94: igmp v2 report 233.171.129.94
14:30:06.134217 IP 192.168.10.1 > 224.0.0.1: igmp query v2
14:30:09.706035 IP 192.168.10.107 > 233.171.129.255: igmp v2 report 233.171.129.255
14:30:14.052507 IP 192.168.10.107 > 233.171.129.94: igmp v2 report 233.171.129.94
# The IGMP-table on the router:
2| 233.171.129.255| NA | 2
2| 233.171.129.094| NA | 2
As you can see, everything is correct. The STB workes and I can watch the TV-channel. The router has the correct IGMP-table and the switch is doing it's job. However, it broadcasts all traffic to every port on the switch, not just the one port the STB is connected to.
So now I turn on the IGMP features (IGMP snooping) on the SLM2008. When I change a TV-channel the following happens:
# The mirror-port on the switch:
(nothing)
# The port on the router:
14:49:43.217074 IP 192.168.10.3 > 233.171.129.94: igmp query v2 [max resp time 10] [gaddr 233.171.129.94]
14:49:43.230585 IP 192.168.10.107 > 233.171.129.105: igmp v2 report 233.171.129.105
14:49:43.266674 IP 192.168.10.107 > 233.171.129.105: igmp v2 report 233.171.129.105
# The output from the STB:
14:49:45.221633 IP 192.168.10.107 > 224.0.0.2: igmp leave 233.171.129.94
14:49:45.233401 IP 192.168.10.107 > 233.171.129.105: igmp v2 report 233.171.129.105
14:49:45.271097 IP 192.168.10.107 > 233.171.129.105: igmp v2 report 233.171.129.105
# The IGMP-table on the router:
2| 233.171.129.105| NA | 2
2| 233.171.129.255| NA | 2
2| 233.171.129.094| NA | 2
This all breaks my IPTV: The STB does not show the channel, the SLM2008 does not send a IGMP-leave to the router and the router thinks I watch two different channels at the same time. If I change the channels some more, this is the IGMP-table on the router:
2| 233.171.129.105| NA | 2
2| 233.171.129.255| NA | 2
2| 233.171.129.094| NA | 2
2| 233.171.129.081| NA | 2
2| 233.171.129.074| NA | 2
2| 233.171.129.055| NA | 2
2| 233.171.129.241| NA | 2
.. and I am DOS'ing myself, since my ISP is sending data for all 6 TV-channels at the same time.
- Why isn't the SLM sending a IGMP-leave to the router? Is it a bug or a feature?
- Why doesn't port-mirroring mirror the traffic sent from the SLM2008?
Best regards,
Vidar Hoel
PS: My ISP is Telenor, and I also work for Telenor.
