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Multicast: Difference between revisions

Multicast (view source)

Revision as of 23:29, 29 August 2022

1,001 bytes added ,  29 August 2022
234.81.130.4 superseded with 234.81.131.194 and others
m (clean up, typos fixed: paramaters → parameters)
(234.81.130.4 superseded with 234.81.131.194 and others)
= FTTC =
 
<strong>Unofficially and completely at own risk</strong>, it has been found to be possible to watch the [https://community.bt.com/t5/YouView-Boxes/IPC6023-Advanced-Diagnosis/td-p/1154880 Test Channel] as described on the BT website, on an AAISP provided FTTC line. This is [https://community.bt.com/t5/YouView-from-BT/Multicast-Test-Channel-URL/td-p/2223426 updated as of 2022]
 
== Example for Debian GNU/Linux ==
eval `tdbdump /var/run/pppd2.tdb | grep CALL_FILE | cut -d'"' -f2`
 
AddAs a workaround to IPv4 not customarily allowing ifindex or interface name specification in addresses, (known as scope or "%", in IPv6) route to the multicast group on the device upon which PPPoE runs, aimed at the openreach modem:
 
echo ip route add 234.81.130131.4194 dev $DEVICE
 
Play stream.
Caveats : It starts when the network receives an IGMP join and stops with IGMP leave.
 
ffplay rtp://234.81.130131.4194:5802
 
or:
vlc rtp://234.81.130131.4194:5802
 
=== Relaying the stream ===
It may happen that the computer hosting PPPoE is in an inconvenient location for watching and that other networked devices should receive copies of the stream. For real use an IGMP proxy would be used but for first testing [http://troglobit.github.io/smcroute smcroute] lets one try multicast even where clients don't send IGMP join and leave correctly, but this also means the stream has to be manually started and stopped.
 
For testing, usingand smcrouteusage, wesmcroute can reflect the multicast to other attached networks. The old SMCroute, doeswould not configure the interface without a legacyan IP address on it, sohowever canthe copyvery WANlatest address:smcroute allows 0.0.0.0 to be used to originate the IGMP3 joins, this needed the upgrade from ip_mreq to ip_mreqn in the smcroute code.
 
Additionally the sysctl rp_filter is disabled on $DEVICE and "all" to allow the incoming multicast without a matching outgoing route, also desirable. iptables and/or nftables would still be used to filter.
ifconfig $DEVICE $IPLOCAL
 
smcroute requires the source address, this was found with wireshark and could be subject to change, <var>int0</var> and <var>ext0</var> are example devices to copy multicast packets to, these could be internal vlans on a home network:
 
smcroutesmcroutectl -aadd $DEVICE <var>109.159.247.1</var>194 234.81.130131.4194 <var>int0 ext0</var>
smcroutectl add $DEVICE 109.159.247.200 234.81.131.200 <var>int0 ext0</var>
smcroutectl add $DEVICE 109.159.247.216 234.81.132.216 <var>int0 ext0</var>
 
To actually start:
 
smcroutesmcroutectl -jjoin $DEVICE 234.81.130131.4194
 
and stop:
 
smcroutesmcroutectl -lleave $DEVICE 234.81.130131.4194
 
see for forwarding statistics:
cat /proc/net/ip_mr_cache && ip mroute show
 
now ffmpeg, vlc or other client can be ran elsewhere on the internal network, if their ethernet interfaces do not have legacy ip addresses and the client does notallow specifyspecification of an interface for IGMP, usewhich is more usual with ipv6, a workaround is <code>ip route add 234.81.130131.4194/32</code> on these devices with a device aiming towards the PPPoE host system.
 
 
 
== Example Notes ==
* [http://ideas.aa.net.uk/?ia=7937 Votes on the idea]
* [http://www.revk.uk/2012/11/multicast.html AAISP Director on Multicast]
 
* [https://www.bt.com/about/sinet BT] and [https://www.openreach.co.uk/cpportal/help/suppliers-information-notes-(sins) openreach] supplier information notes, especially BT 511 and openreach 503
 
 
Michael
56

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