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Distinguished Sage
Distinguished Sage
1,563 Views
Message 11 of 24

Re: Constant IGMP traffic

I am going to have a good guess as to what this could be.

 

The old YouView platform kept the programme guide stored on the YouView box, and just updated it when needed.

 

The new YouView platform stores the information in the Cloud, and therefore the YouView guide has to be continually updated from the cloud. It allso allows YouView to force feed you stuff it thinks you need to see.

 

In fact, the whole new YouView software is reliant on an Internet connection.

 

I suspect that your "problem" only started when YouView moved to the new platform.

 

 

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BT TV Expert
BT TV Expert
1,491 Views
Message 12 of 24

Re: Constant IGMP traffic

Hi therealbraderz,

 

As you have identified we are delivering additional information to the box in the latest software release. This is to provide BT Sport programme timing updates (start time and finish time) to the BT YouView STB. We are considering using this in the future to improve recordings when events overrun. We want to avoid customer recordings missing the end of a sporting event if is it running over.   This is a stream of data running at 0.01Mbytes/sec that will be delivered continually to your BT YouView box. This traffic does not count towards any broadband allowance you may have.

 

If your BT YouView box is connected directly to the BT Home Hub the extra traffic that is being used in the latest software release will not affect anything else in your network and you can ignore the following. If your YouView box is connected to a non-BT router or connected via a WiFi router or Apple Time capsule you may want to enable “IGMP Snooping” on those non-BT devices to ensure the extra multicast packets don’t reach anything else on your network. Don’t worry if this isn’t possible as the extra multicast stream is less than 0.01Mbytes/sec and just carries programme information to signal which Extra TV programmes are being transmitted.

 

I'm on holiday next week but will try and catchup on here at some point.

 

Steve

Community ModeratorSteveM
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cdturri
Aspiring Contributor
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Message 13 of 24

Re: Constant IGMP traffic

First of all I would like to thank the original poster and Steve for posting on this thread as it has helped me solve my network issues and finally get reliable wifi in the house back again. While Steve claims this new constant multicast traffic is "low bandwidth" and won't "affect anything" I beg to differ given the problems I found. I had IGMP Snooping enabled in my router but this still meant that the multicast traffic was being spread across my whole network. The reason was due to my network topology. This is how my devices were connected:

 

BT Openreach VDSL modem => Asus Router => 24 port Switch => all other devices including BT TV Box

 

My Asus router supports both IGMP Proxy and IGMP Snooping. As you can see from my network topology the BT TV Box is connected to a 24 port Switch and then that switch is connected to the Asus router. So even with IGMP Snooping enabled the Asus router was still sending multicast traffic to the switch (as the BT box was requesting it via the connection to the switch) which in turn meant the switch will broadcast it to all my network devices connected to it. As indicated by Steve BT made a change on Nov 2017 where they now continually broadcasting in multicast some programming data which will be used to improve recordings when events overrun. When I installed BT TV I did not noticed any wifi issues even though the multicast traffic was being spread to my whole network, but probably just because I was only occasionally watching BT Sport. In the last few weeks some of my wifi devices started to have wifi issues where they will drop out of my wifi network. I have a mesh wifi system (Ubiquiti AcPro) and the management interface showed that there was too much traffic on the wifi network. After some research I nailed it down to the multicast traffic of the BT TV box. But due to the change BT did even after switching the BT TV box off it would still mean I would get this constant multicast traffic going to all my network devices, even the wifi ones. The solution for my problem was as follows:

 

1) Run a separate network cable between the Asus Router and the 24 port Switch. This would allow the Asus router to correctly do IGMP Snooping and send the multicast traffic ONLY on the second port/cable to the switch, not the original cable that connected the router and the switch.

2) Create a vLAN on my switch to separate the traffic for this second cable between the router and the switch. The vLAN was formed of two ports only: the second port/cable to the switch and the cable/port for the BT TV box. This meant that when the switch got multicast traffic via the second cable from the Asus router it wouldn't broadcast it to the rest of network devices connected to my switch as the vLAN was isolating it and it was only being sent to the BT TV box. 

 

This might sound like a complicated thing to do but is relatively easy to set up if you roughly know what you are doing. So in summary if you connect your BT TV Box directly to your BT Home Hub (or any other router which supports IGMP Snooping) you won't see the problems I am describing. But if you connect your BT TV Box via a switch/hub or your network topology is different this post may apply to you. And this issue is even more critical if you don't use your BT Home Hub/wifi router for wifi and have separate wifi access points connected to a switch. So you need to see what's your network topology and what is the right solution for you. vLANs, IGMP Snooping, or both might be needed. If you use a switch you might need a switch which supports vLANs or IGMP Snooping or both. IGMP Snooping is more CPU intensive than vLANs, although most recent decent routers and switches should be able to to do IGMP Snooping without much effort. 

The most clear indication that multicast packets are being sent to your whole network is that you will see ALL of your switch port LEDs constantly blinking and never rest. They will also all blink at the same time which is indicating the same packet is being sent to all your switch's ports at the same time. Final tip is that if you make changes to your network topology which impact IGMP Snooping you may need to reboot any devices (routers/switches) doing IGMP Snooping for them to readjust to the new topology.

 

Hope this helps other people!

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Peteman
Aspiring Contributor
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Message 14 of 24

Re: Constant IGMP traffic

I thought it worth adding my configuration that has recently started causing performance problems on my Windows 10 desktop PC.

I have recently (last week or so) noticed the network performance on my PC was very variable, OK one second then rather poor the next.
BT broadband was working fine and I struggled to see what was causing the problem.
I eventually ran a Wireshark trace on the PC and saw all the UDP packets detailed in the first entry of this topic.

Obviously these are not intended for the PC but just for the BT Youview box.
The reason they were hitting the PC all the time was down to my wired LAN setup. Which is as follows:-

BT HH6 eth0 ==> Powerline AP adaptor  ====> Powerline EP Adaptor ==> BT Youview Box
                                                                                 |
                                                                                 |
                                                                                ====> Powerline EP Adaptor ==> Windows PC
                                                                                |
                                                                                |
                                                                               ====> Powerline EP Adaptor ==> Sony Bravia TV

So even though the UDP packets were destined just for the BT Youview box the BT Hub 6 can only determine that they are for ethernet port 0,  but that means they are also reaching my PC  (and presumably the Sony TV!)
If I power off the BT Youview box the UDP packets stop and so does the intermittent network response problems on the PC.
The problem also stops if I switch to using wifi to connect the PC to the BT Hub rather than ethernet via the Comtrend adaptors.


I have had this ethernet setup for a number of years with no problems, and the performance problem only seems to have started occurring very recently, last few weeks, even though the earlier updates suggest that the Youview platform changed some months ago.

So has the ammount or frequency of BT program information recently been increased again?
I see around 7-10 UDP packets per second ALL the time.

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cdturri
Aspiring Contributor
940 Views
Message 15 of 24

Re: Constant IGMP traffic

Hi. That’s exactly the problem I had. I suggest that you look at running a network cable to connect your PC directly to the BT router, the router will take care of the filtering. Ultimately you don’t want these packets getting into your network.
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Peteman
Aspiring Contributor
925 Views
Message 16 of 24

Re: Constant IGMP traffic

Router downstairs, PC upstairs and TV in a different room.

Don't think the wife would be too keen on cables everywhere so just going to move for wifi on the PC and TV, and just leave the Youview box connected via ethernet over the Powerline adaptors.

Response seems perfectly OK going via 5GHZ wireless (at present anyway).

I'd still like to know why the problem seems to have gotten worse over the last week or so though???

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BT TV Expert
BT TV Expert
917 Views
Message 17 of 24

Re: Constant IGMP traffic

That level of traffic is not enough to impact a network interface on a PC, at a low level the interface will not even be subscribed to the multicast group so will not even take the packets up to a software layer. Do you ever watch IP channels (BT Sport etc) on the Youview box? In that situation, the PC would be receiving multi megabit streams.

Steve
Community ModeratorSteveM
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cdturri
Aspiring Contributor
909 Views
Message 18 of 24

Re: Constant IGMP traffic

Yes good point. In my tests the BT Sports HD stream uses ~9 mbits whereas the 4K UHD stream uses ~30 mbits. These could add up a well if you recording one stream and watching another one. I’m also not convinced that the streams stop immediately after you stop watching a channel.
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BT TV Expert
BT TV Expert
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Message 19 of 24

Re: Constant IGMP traffic

If you tune to another channel, it will leave the stream. If you just turn box off, or remove power etc, the stream will time out after 4 minutes 20 seconds Smiley Happy
Community ModeratorSteveM
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TimCurtis
Recognised Expert
884 Views
Message 20 of 24

Re: Constant IGMP traffic

My son has just had Sky-Q installed and when he uses his BT zapper box to watch BT Sport the Sky-Q wireless mesh network gets screwed in that the receiving devices won't receive anything from the Q box. Both the zapper box & the Sky-Q box are connected to the same 5-port unmanaged switch which in turn connects via a cat-6 ethernet cable to his Asus DSL-AC68U router.

He has partly solved this by connecting his bedrooms Q receiver via ethernet but the kids bedrooms aren't so easily connected.

As this seems relevant to this thread - well sort of - I thought I'd see if anybody has a solution. If an solution is found then I could impress him with my technical skills.Smiley Happy

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