sin 511 issue 3.1 - bt wholesale tv connect (tvc)
TRANSCRIPT
British Telecommunications plc 2020
Registered Office 81 Newgate Street LONDON EC1A 7AJ
Registered in England no.1800000
SIN 511 Issue 3.1
July 2020
Suppliers’ Information Note
For The BT Network
BT Wholesale TV Connect (TVC)
Service & Interface Description
Each SIN is the copyright of British Telecommunications plc. Reproduction of the SIN is permitted only in its
entirety, to disseminate information on the BT Network within your organisation. You must not edit or amend
any SIN or reproduce extracts. You must not remove BT trademarks, notices, headings or copyright markings.
This document does not form a part of any contract with BT customers or suppliers.
Users of this document should not rely solely on the information in this document, but should carry out their
own tests to satisfy themselves that terminal equipment will work with the BT network.
BT reserves the right to amend or replace any or all of the information in this document.
BT shall have no liability in contract, tort or otherwise for any loss or damage, howsoever arising from use of, or
reliance upon, the information in this document by any person.
Due to technological limitations, a very small percentage of customer interfaces may not comply with some of
the individual characteristics, which may be defined in this document.
Publication of this Suppliers’ Information Note does not give or imply any licence to any intellectual property
rights belonging to British Telecommunications plc or others. It is your sole responsibility to obtain any
licences, permissions or consents which may be necessary if you choose to act on the information supplied in
the SIN.
Those BT services marked indicates it is a registered trade mark of British Telecommunications plc.
Those BT services marked indicates it is a trade mark of British Telecommunications plc.
This SIN is available in Portable Document Format (pdf) from: https://www.bt.com/about/sinet
Enquiries relating to this document should be directed to: [email protected]
SIN 511 Issue 3.1 British Telecommunications plc Page 2 of 23
CONTENTS
1. INTRODUCTION ....................................................................................................................................... 3
2. SERVICE OUTLINE ................................................................................................................................. 4
2.1 ARCHITECTURE .............................................................................................................................................. 4 2.1.1 Content delivery to TV Connect Headend ........................................................................................... 4 2.1.2 Multicast Content Distribution ............................................................................................................ 6 2.1.3 Home Environment/End User Experience ........................................................................................... 6
2.2 ISP SERVICES ................................................................................................................................................ 7 2.3 TV CONNECT INFRASTRUCTURE DESCRIPTION .............................................................................................. 8
2.3.1 Overview .............................................................................................................................................. 8 2.3.2 End-To-End Service Flow Example (Fibre access, FTTC and FTTP via Openreach GEA) ............... 9 2.3.3 End-To-End Service Flow Example (Copper access from an MSAN) ............................................... 10
3. ISP MULTICAST INGESTION INTO TVC ......................................................................................... 12
3.1 CHANNEL INGRESS TO TV CONNECT HEAD END. ........................................................................................ 12 3.2 MULTICAST STREAM EGRESS ...................................................................................................................... 12 3.3 PHYSICAL ETHERNET PRESENTATION .......................................................................................................... 13
3.3.1 1000Base-T (IEEE 802.3ab) .............................................................................................................. 13 3.3.2 1000Base-X (IEEE 802.3z) ................................................................................................................ 13 3.3.3 10GBase-x (IEEE 802.3ae) ............................................................................................................... 13
4. IP MULTICAST STREAMS ................................................................................................................... 15
4.1 MAXIMUM BANDWIDTH .............................................................................................................................. 15 4.2 CHANNEL AGGREGATION ............................................................................................................................ 15 4.3 MULTICAST SOURCE AND GROUP IP ADDRESSES ......................................................................................... 15 4.4 RETRANSMISSION ........................................................................................................................................ 15 5. TV CONNECT CUSTOMER PREMISES EQUIPMENT (CPE) IGMP REQUIREMENTS .......... 16
5.1 MESSAGE SEQUENCING ............................................................................................................................... 16 5.2 SET TOP BOX (STB) FUNCTIONS ................................................................................................................. 16 5.3 RESIDENTIAL GATEWAY (HOME ROUTER) FUNCTIONS [3] ........................................................................... 16
5.3.1 End user connected via Openreach GEA (FTTC and FTTP) ............................................................ 17 5.3.2 End user connected to an MSAN (WBC copper) ............................................................................... 17 5.3.3 ISP utilising the L2TP handover service option for WBC ................................................................. 18
6. SERVICE AVAILABILITY .................................................................................................................... 19
7. ISP RESPONSIBILITIES ........................................................................................................................ 19
8. REFERENCES .......................................................................................................................................... 20
9. ABBREVIATIONS ................................................................................................................................... 21
10. HISTORY .................................................................................................................................................. 23
FIGURES
FIGURE 1 BT TV CONNECT SERVICE ARCHITECTURE 4
FIGURE 2 ISP CONNECTIVITY OPTIONS 5
FIGURE 3 OVERVIEW OF NETWORK INFRASTRUCTURE 8
FIGURE 4 END TO END FLOWS FOR AN END USER CONNECTED VIA FIBRE, FTTC AND FTTP VIA OPENREACH
GEA 9
FIGURE 5 END TO END FLOWS FOR AN END USER WITH COPPER ACCESS CONNECTED TO AN MSAN 10
FIGURE 6 TV CONNECT IGMP FLOWS 16
SIN 511 Issue 3.1 British Telecommunications plc Page 3 of 23
1. Introduction
This Supplier’s Information Note (SIN) 511 provides service description information for
customers of the BT Wholesale TV Connect (TVC) family of products. TVC delivers broadcast
quality TV over BT Wholesale’s dedicated broadband network.
TVC enables ISPs to deliver reliable and cost effective TV services to their end users across
the breadth of the BT 21CN broadband network making TV Connect a viable alternative to
traditional Satellite and DTT signal transmission. This coverage is achieved through our state
of the art, multicast enabled IP based network.
It should be noted that the information contained within this SIN might be subject to change
due to either the results of BT testing or feedback from trial participants. Please check with the
http://www.btplc.com/sinet/ site to ensure you have the latest version of this document.
Numbers in square brackets [ ] denote further references, as listed in Section 8.
Further information about the commercial aspects of TV Connect can be obtained by
contacting your Account Manager or Customer Relationship Manager.
SIN 511 Issue 3.1 British Telecommunications plc Page 4 of 23
2. Service Outline
2.1 Architecture
Figure 1 BT TV Connect Service Architecture
The TV Connect Service Architecture is indicated in Figure 1. The TV Connect service is built
on top of the underlying Wholesale Broadband Connect (WBC) service.
An ISP planning to purchase the TV Connect (TVC) service will utilise the WBC
PTA or L2TP handover service.
The TV Connect service will multicast live streaming TV Channels from ingress in
the TV Connect Head End at the MIP to end users on the WBC platform.
2.1.1 Content delivery to TV Connect Headend
The ISP will be expected to provide TV content to the Head End, often in
conjunction with a content provider subject to a commercial relationship.
The ISP will be expected to deliver content to the TV Connect Headend as
compressed (encoded IP multicast) content.
The ISP would provide compressed content, encoding, (optionally) encrypting and
conditioning the content themselves, ready for multicast distribution.
The ISP will be entirely responsible for the encryption of their TV channels for
conditional access by end users.
The ISP is expected to provide aggregated multi channel content to the Head End
via the TVC Multicast Ingest Point (MIP) using Ethernet links.
The ISP will be responsible for the provision, management and ownership of the
Ethernet Links up to the agreed handover port in the MIP. This includes utilisation
of bandwidth within these links such that overall bandwidth does not exceed the
overall bandwidth envelope agreed with BT Wholesale.
21C
TVC MIP Headend
ISP Encoding/Encryption
Openreach
MIP Input
21C Interconnect
ISP RET
ISP
Multicast TV channels PathUnicast WBC data pathTV Connect Interface
BRAS/LAC
Residential Gateway
STB
Other Devices
SIN 511 Issue 3.1 British Telecommunications plc Page 5 of 23
The TVC MIP offers a Geo-Resilient option whereby the ISP may additionally
present their content at the second (Geo-Resilient) site Figure 2 illustrates the three
options available wherein:
o ISP A connects via 2 links to each site (one to each landing point at each
site).
o ISP B connects via 1 link to each site (one to the primary landing point at
each site).
o ISP C connects via 2 links to only the main site, BT Tower (one to each
landing point at BT Tower).
Each of the options clearly offer different levels of physical or geographic
resilience.
Note that the option to connect exclusively at the secondary site is not offered.
The ISP may elect for different resilient options on a per channel basis, however
utilising the same resilient option for all channels provided by the ISP is strongly
recommended.
Figure 2 ISP Connectivity Options
21CDistribution
BT Tower(Main Headend Site)
TVC/MIPSwitch X
TVC/MIPHER X
MAR 1TVC/MIPSwitch Y
TVC/MIPHER Y
BT Colombo House(Secondary Headend Site)
TVC/MIPSwitch X
TVC/MIPHER X
TVC/MIPSwitch Y
TVC/MIPHER Y
MAR 2
ISP B
ISP CISP A
ISP A
SIN 511 Issue 3.1 British Telecommunications plc Page 6 of 23
2.1.2 Multicast Content Distribution
The TV Connect traffic will be delivered across the end to end network over a
separate logical path from the WBC data traffic. (See Section 2.3.1)
The ISP may choose to provide its own Retransmission (RET) solution for packet
repair. A feed of the full multiplex of their channels may be supplied by BT
Wholesale to support such a solution. Details of handover points will be agreed
during contract negotiation subject to a successful development and test programme
with the ISP. The ISP will be responsible for interconnection to their own
equipment from the agreed handover points. The ISP may forward retransmission
repair and control traffic via the WBC service.
2.1.3 Home Environment/End User Experience
The end user access link may be via WBC fibre or copper as provided by
Openreach.
The ISP will be expected to provide the required equipment (e.g. a Residential
Gateway (home router) and set top box (STB) or other equipment) to an end user
in order to support the live streaming of TV channels.
The ISP will be responsible for end user packages, end user repair and end user
billing.
BT Wholesale will provide interfaces to support provision, repair, service
monitoring and billing.
SIN 511 Issue 3.1 British Telecommunications plc Page 7 of 23
2.2 ISP Services
The TV Connect product is an optional feature of the WBC service that allows live streamed
content to be multicast delivered to End Users from a Head End within the BT Wholesale
network.
The WBC SIN is available from https://www.bt.com/about/sinet
TVC Service Configuration
An ISP will buy TV Connect from BT Wholesale to deliver channels to its WBC
broadband end users.
BT Wholesale takes on the delivery of TV channels to all the WBC end users as part of
the product.
Only a WBC customer (ISP) can take up the TV Connect service.
The TV Connect service is available to ISPs that take the WBC PTA (PPP termination
and aggregation service) and/or the WBC L2TP (Layer 2 Tunnelling Protocol)
handover service.
The ISP will supply TV channel content to the BT Wholesale TV Connect Head End.
The ISP will be responsible for the Residential Gateway (home router) and set top box
(STB) functionality within the end user’s environment.
It is the responsibility of the ISP to provide any TV Channel restrictions to individual
WBC broadband end users it deems necessary.
For all requests to provide channel capacity within the current network capacity (as agreed and
managed with BT Wholesale) available on the TV Connect network, BT Wholesale will deliver
channel capacity to an ISP’s end users who are on WBC fibre and copper, in line with
forecasted channel demand from the ISP following the process as set out in the TV Connect
Product Handbook.
Where there is a need to provide additional channel capacity beyond the current network
capacity available, the ISP can submit a request by contacting their account team who will raise
a request in to the TV Connect Product Line via the Statement of Requirements (SoR) process.
An assessment of such a request will then be carried out to determine if the demand for
additional capacity can be accommodated in line with the SoR process timelines.
An ISP can check the availability of Multicast at WBC exchanges by using the Broadband
Availability Checker available at http://www.btwholesale.com/ via the Routing and Planning
section under the Applications tab.
When the ISP is ready to raise an order to provide/add channels, all of the channel details -
including whether or not the channel/s are required on both fibre and copper networks - must
be clearly marked in the appropriate fields on the TV Connect CRF.
SIN 511 Issue 3.1 British Telecommunications plc Page 8 of 23
2.3 TV Connect Infrastructure Description
2.3.1 Overview
An overview of the network infrastructure that supports TV Connect is illustrated in Figure 3.
Figure 3 Overview of Network Infrastructure
The TV Connect service accepts TV channels from a TV content provider into the TV Connect
Head End as compressed streams via the TVC Multicast Ingest Point (MIP) capability.
Compressed (encoded and optionally encrypted) TV channels are checked and policed at the
Multicast Ingest Point (MIP) to ensure that a) the maximum per channel bandwidth, as
contracted by the ISP is not exceeded and b) that the maximum overall bandwidth envelope for
all channels, as contracted by the ISP is not exceeded. Error recovery via Forward Error
Correction (FEC) is not supported, but appropriate Service IP Addressing is provided.
The TV Connect service delivers multicast channels to end users via MSANs and Openreach
GEA. A combination of IP and Ethernet Multicast within BT’s 21C core, at the MSAN (copper
access), and within the Openreach GEA equipment (fibre access, FTTC and FTTP), is then
used to replicate and deliver TV Connect Channels to WBC End Users (EUs). WBC End Users
will then receive the TV channel(s) when requested using the IGMP protocol, as described in
sections 2.3.2 and 2.3.3.
The service is designed for high availability, so TV Connect traffic is delivered over resilient
paths into and across the BT Wholesale 21C infrastructure to MSANs and Openreach GEA
handover points.
BT Wholesale
BT Tower (Main Site)
BT Colombo (Geo-resilient Site)
Residential Gateway
STB
Openreach
Openreach GEA
ISP Encryption/Encoding
Compressed, EncryptedTV Content in
MIP
MIP
MSAN
EES
EEA
L2S
MAR
MAR
PON
DSLAM
21C Core
BRAS/LAC
BEA
LNS
MSIL MSIL
ISP N/WISP N/W
Openreach SMPF
Openreach Cablelink Broadband
ISP
FTTP
FTTC
Residential Gateway
STB
Residential Gateway
STB
ISP Encryption/Encoding
Compressed, EncryptedTV Content in
MIP
MIP
4x Ethernet
4x Ethernet
Multicast TV channels Path
MIP Channels Path
Unicast WBC data path
SIN 511 Issue 3.1 British Telecommunications plc Page 9 of 23
2.3.2 End-To-End Service Flow Example (Fibre access, FTTC and FTTP via Openreach
GEA)
An overview of end user end-to-end flows for an end user connected via Openreach GEA is
illustrated in Figure 4.
Figure 4 End to End flows for an end user connected via
fibre, FTTC and FTTP via Openreach GEA
Channel join request
1. End user issues channel join request via Set Top Box
2. Home router issues proxy request into TV Connect path to Openreach GEA head end
3. Home router replicates proxy request and issues it into PPP path to BRAS
4. Openreach GEA head end receives proxy request from home router and delivers
requested channel to end user
5. BRAS receives proxy request from home router and shapes broadband end user
broadband PPP session to a rate reduced by an amount equal to requested TV channel
bandwidth.
6. In the case of an ISP taking the L2TP handover option for WBC, the home router
replicates the proxy request so that it is forwarded via the PPP session over an L2TP
tunnel from the LAC within the BT platform to the LNS within the ISP’s network.
7. The LNS within the ISP’s network receives the proxy request and is expected to shape
the broadband end user PPP session to a rate reduced by an amount equal to the
requested TV channel bandwidth.
BT Wholesale
TV Headend
Residential Gateway
STB
Openreach
Openreach GEA
MSAN
EES
EEA
L2S
MAR
MAR
PON
DSLAM
21C Core
BRAS/LAC
BEA
LNS
MSIL MSIL
ISP N/WISP N/W
Openreach SMPF
Openreach Cablelink Broadband
ISP
FTTP
FTTC
Residential Gateway
STB
Residential Gateway
STB
ISP Encryption/Encoding
Compressed, EncryptedTV Content in
MIP
MIP
7
6
5
4
4
3
31
12
2
4x Ethernet
Multicast TV channels Path
MIP Channels Path
Unicast WBC data path
IGMP Messaging
SIN 511 Issue 3.1 British Telecommunications plc Page 10 of 23
Channel Leave Request
The channel leave request sequence functions in a similar fashion.
1. End user issues channel leave request via Set Top Box
2. Home router issues proxy request into TV Connect path to Openreach GEA head end
3. Home router replicates proxy request and issues it into PPP path to BRAS
4. Openreach GEA head end receives proxy request from home router and stops
delivering the specified channel to the end user
5. BRAS receives proxy request from home router and removes the shaping on the
broadband end user broadband PPP session by an amount equal to the bandwidth of the
TV channel specified in the leave request.
6. In the case of an ISP taking the L2TP handover option for WBC, the home router
replicates the proxy request so that it is forwarded via the PPP session over an L2TP
tunnel from the LAC within the BT platform to the LNS within the ISP’s network.
7. The LNS within the ISP’s network receives the proxy request and is expected to remove
the shaping on the broadband end user PPP session by an amount equal to the
bandwidth of the TV channel specified in the leave request.
2.3.3 End-To-End Service Flow Example (Copper access from an MSAN)
An overview of end user end-to-end flows for an end user connected to an MSAN is illustrated
in Figure 5.
Figure 5 End to End flows for an end user with copper access connected to an MSAN
BT Wholesale
TV Headend
Residential Gateway
STB
Openreach
MSAN
EES
EEA
L2S
MAR
MAR
PON
DSLAM
21C Core
BRAS/LAC
BEA
LNS
MSIL MSIL
ISP N/WISP N/W
Openreach SMPF
Openreach Cablelink Broadband
ISP
FTTP
FTTC
Residential Gateway
STB
Residential Gateway
STB
ISP Encryption/Encoding
Compressed, EncryptedTV Content in
MIP
MIP
7
6
5
4
3
12
Openreach GEA
4x Ethernet
Multicast TV channels Path
MIP Channels Path
Unicast WBC data path
IGMP Messaging
SIN 511 Issue 3.1 British Telecommunications plc Page 11 of 23
Channel Join Request
1. End user issues channel join request via Set Top Box.
2. Home router issues proxy request into TV Connect path to MSAN.
3. Home router replicates proxy request and issues it into PPP path to BRAS.
4. MSAN receives proxy request from home router and delivers requested channel to end
user.
5. BRAS receives proxy request from home router and shapes the broadband end user’s
PPP session to a rate reduced by an amount equal to the requested TV channel
bandwidth.
6. In the case of an ISP taking the L2TP handover option for WBC, the home router
replicates the proxy request so that it is forwarded via the PPP session over an L2TP
tunnel from the LAC within the BT platform to the LNS within the ISP’s network.
7. The LNS within the ISP’s network receives the proxy request and is expected to shape
the broadband end user PPP session to a rate reduced by an amount equal to the
requested TV channel bandwidth.
Channel Leave Request
The channel leave request sequence functions in a similar fashion.
1. End user issues channel leave request via Set Top Box.
2. Home router issues proxy request into TV Connect path to MSAN.
3. Home router replicates proxy request and issues it into PPP path to BRAS.
4. MSAN receives proxy request from home router and stops delivering the channel down
to the end user.
5. BRAS receives proxy request from home router and removes the shaping on the
broadband end user’s PPP session by an amount equal to the bandwidth of the TV
channel specified in the leave request.
6. In the case of an ISP taking the L2TP handover option for WBC, the home router
replicates the proxy request so that it is forwarded via the PPP session over an L2TP
tunnel from the LAC within the BT platform to the LNS within the ISP’s network.
7. The LNS within the ISP’s network receives the proxy request and is expected to shape
the broadband end user PPP session to a rate reduced by an amount equal to the
requested TV channel bandwidth.
SIN 511 Issue 3.1 British Telecommunications plc Page 12 of 23
3. ISP Multicast Ingestion into TVC
3.1 Channel Ingress to TV Connect Head End.
Presentation of [ISP encoded and encrypted] programme sources from the ISP’s network to the
TVC Head End will be by Ethernet links, as per specification in section 3.3. The number of
links provided will depend on the resilience option selected by the ISP (see Section 2.1.1).
The ISP devices to be connected into the TVC Multicast Ingest Point (MIP) can be located
locally (within range of CAT5e cable, 100 metres maximum or multi-mode fibre optic cable,
550m maximum) or remotely in a location to be agreed with the ISP. For devices that are
remotely located the ISP will be responsible for the provision of interconnecting access circuits
and any associated security arrangements. BT recommends the use of the Openreach Ethernet
Access Direct (EAD) products.
At least two Ethernet ports are available on the TVC MIP to accept the programme streams
from the ISP [4], the location and number of ports is dependent on the resilient option chosen
by the ISP as illustrated in Figure 2 and total stream bandwidth requirements.
All signals between the ISP and the Head End will be carried over these physical links.
It is assumed that the programme streams traversing these links will be properly conformed
MPEG2 Single Programme Transport Streams [2].
MIP will monitor and may police ISP ingest bandwidth to ensure that:
The overall bandwidth offered by the ISP into TVC does not exceed the overall
bandwidth envelope agreed with BT Wholesale.
The individual channel bandwidth of each channel offered by the ISP into TVC does
not exceed the individual channel bandwidth agreed with BT Wholesale.
3.2 Multicast Stream Egress
Subject to agreement with BT Wholesale and technical capability, all the channels belonging
to an ISP may be made available to the ISP at a small set of handover points, which are to be
agreed during contract negotiation. The physical interface presentation is as defined in section
3.3. BT Wholesale will only duplicate multicast programme streams the ISP sends into the
TVC MIP as defined in section 3.1 (i.e. another ISP’s programme streams will not be
duplicated back to the ISP).
Where an ISP has multiple interfaces into the MIP at BT Tower and optionally Colombo House
to ingest channels to provide resiliency, BT Wholesale will offer separate copies of each
resilient path back to the ISP at the same location, via an agreed physical presentation as
defined in section 3.3. The ingest and egress interfaces will be separate and may be of different
physical presentation subject to availability and agreement between BT Wholesale and the ISP.
In addition to what is offered in section 4.4, BT Wholesale will offer duplicates of all of the
ISP’s channels at sites beyond BT Tower and Colombo House. Only one copy will be offered
per resilient path at each location, and is subject to suitability of providing this facility at each
location. For example, at the MAR site up to 5 interfaces for duplicate streams are available –
1 off each link from BT Tower and Colombo house (4 total) and 1 off link into the 21CN core
network. The physical presentation of copied streams at the MAR sites and beyond [away from
the BT Tower and Colombo House sites] will be 10GBASE-LR only.
SIN 511 Issue 3.1 British Telecommunications plc Page 13 of 23
3.3 Physical Ethernet Presentation
3.3.1 1000Base-T (IEEE 802.3ab)
The ISP may provide their programme streams at ingest points using 1000Base-T (IEEE
802.3ab) interfaces, and where capacity requirements dictate provide their multiplex of
multicast channels using multiple physical interfaces per resilient path (e.g. to provide 1.1Gbps
of multicast this can be split over 2 1000Base-T ports, each carrying 550Mbps). Each physical
port can ingest up to 1Gbps of Ethernet traffic, however the volume of multicast programme
traffic will be less than this due to headers and other Ethernet protocol overheads. BT
Wholesale suggest limiting the utilisation of 1Gbps links to 900Mbps to avoid potential high
jitter and packet loss observed in some test scenarios.
The definition of this interface type dictates the use of twisted pair copper CAT5E or higher
grade cable, which will limit the cable distance between the ingest point and ISP equipment to
100 metres.
This interface type is only offered for ingest traffic only.
3.3.2 1000Base-X (IEEE 802.3z)
The ISP may provide their programme streams at ingest points using 1000Base-X (IEEE
802.3z) interfaces, and where capacity requirements dictate provide their multiplex of multicast
channels using multiple physical interfaces per resilient path (e.g. to provide 1.1Gbps of
multicast this can be split over 2 1000Base-X ports, each carrying 550Mbps). Each physical
port can ingest up to 1Gbps of Ethernet traffic, however the volume of multicast programme
traffic will be less than this due to headers and other Ethernet protocol overheads. BT
Wholesale suggest limiting the utilisation of 1Gbps links to 900Mbps to avoid potential high
jitter and packet loss observed in some test scenarios.
The definition of this interface type dictates the use of fibre optic cable, and the MIP product
will only support the use of multi-mode fibre cable. Although the cable length limit of using
OM4 grade fibre at 1Gbps speed is above 550m, the MIP product will restrict the fibre length
to 550 metres between the ISP equipment and the ingest port to provide alignment with the use
of the same fibre cable at 10Gbps speed.
This interface type is only offered for ingest traffic only.
3.3.3 10GBase-x (IEEE 802.3ae)
The MIP product supports the use of 10Gbps Ethernet interfaces for both ingest and egress
multicast traffic. The restrictions of use are indicated below.
At the TV Headend sites (BT Tower and Colombo House) the expectation is that any
connectivity between the TVC MIP and ISP equipment will be in-building, therefore only
10GBase-SR interfaces will be supported for traffic ingest links (ISP sending multicast
programme streams into the MIP) and for traffic egress links (where an ISP requests
programme streams to be duplicated back to their equipment from agreed monitoring points in
the MIP).
To mitigate against connectivity faults and provide greater reliability only OM4 grade multi-
mode fibre shall be used for connectivity between ISP equipment and the TVC MIP equipment.
This offers a theoretical cable distance limit of 550 metres, however losses caused by splices
and patching of cables should be considered to assess the quality and light levels of the links,
which may result in a shorter usable cable distance.
SIN 511 Issue 3.1 British Telecommunications plc Page 14 of 23
For the egress interfaces in the MAR sites and beyond in the 21CN network, only 10GBase-
LR interfaces are supported, requiring the use of single-mode fibre cables for a maximum reach
of 10km.
SIN 511 Issue 3.1 British Telecommunications plc Page 15 of 23
4. IP Multicast Streams
4.1 Maximum Bandwidth
The maximum bandwidth per SPTS Programme Channel shall be 30Mbps in the Wholesale
Network
4.2 Channel Aggregation
The TV Connect product aggregate all the ISP’s channels together to deliver as IP Multicast
for transport across the core of the 21C network. Each channel is identified by unique group
and source IP address and transported together in this group of IP multicast streams.
4.3 Multicast Source and Group IP addresses
The ISP will be expected to complete a Customer Requirements Form (CRF) in conjunction
with BT Wholesale. Multicast group and source addresses will be agreed between BT
Wholesale and the ISP with regards to allocation for each channel during the order process.
The multicast group IP address is used to uniquely identify a particular TV channel.
The multicast source IP address is used to identify the network source equipment of the TV
channel within the TV Connect Head End and is required for multicast routing and geo-resilient
failover.
4.4 Retransmission
In order to facilitate packet repair by retransmission by the ISP, all of the channels belonging
to an ISP may be duplicated and made available to the ISP at a small set of handover points,
which are to be agreed during contract negotiation.
Retransmission repair and control packets may be forwarded via the WBC data service. It is
recommended that an ISP make use of the priority best effort traffic marking for retransmission
repair and control traffic [5] in order to ensure a good experience for end users.
SIN 511 Issue 3.1 British Telecommunications plc Page 16 of 23
5. TV Connect Customer Premises Equipment (CPE) IGMP Requirements
5.1 Message Sequencing
It is expected that IGMPv3 will be used to signal access to TV Connect channels. An end user
will be joined to a selected channel via
Openreach GEA – fibre to the cabinet (FTTC) or fibre to the home (FTTP).
MSAN – WBC copper
The IGMP messaging sequence is indicated in Figure 6.
Figure 6 TV Connect IGMP flows
5.2 Set Top Box (STB) Functions
The set top box will generate IGMP join and leave messages in response to end user requests
(e.g. channel selection changes) and respond to IGMP query requests (from upstream network
equipment).
The set top box may use the WBC service to communicate with retransmission servers for
packet repair or access other ISP services.
5.3 Residential Gateway (home router) Functions [3]
• The End user Residential Gateway (RG) acts as an IGMP proxy routing agent,
supports IGMP snooping and forks IGMP messages for sending up the TV Connect
and Broadband paths
• Support for IGMPv3 is required on the Residential Gateway
• The TV Connect product will only support IGMPv3 [1]
• The TV Connect product will support IGMPv3 Any Source Multicast (*,G).
EU IGMP Domain Access Network IGMP Domain
TV Connect Multicast PathUnicast WBC Broadband Traffic path
Residential GatewaySTB
OR GEA / MSAN
12 3
2
47
6 5 HierarchicalShaping
BRAS
General & Specific IGMP Queries
Unsolicited IGMP messages, and reports in response to queries
Multicast Group to Bandwidth Table (maintained by OSS)
Residential Gateway Forks IGMP Messages
Key:
SIN 511 Issue 3.1 British Telecommunications plc Page 17 of 23
• The TV Connect product will not support IGMPv3 Source Specific Multicast (S,G).
• The IGMP protocol has no acknowledgements, in consequence
• Multiple IGMP requests are to be sent by the Residential Gateway. 2 IGMP
requests should be sent initially (IGMPv3 default setting). The “robustness
variable” setting may be adjusted if required in consultation with BT
Wholesale during trials.
• The “Unsolicited report intervals” should be set to 1 second initially (IGMPv3
default setting).
• The Residential Gateway should prioritise IGMP joins and leaves upstream (802.1p
marking of 3 or above)
• Responses to IGMP Queries (keep-alives) by the Residential Gateway shall only be
returned over the interface through which the Queries were received.
5.3.1 End user connected via Openreach GEA (FTTC and FTTP)
For an end user connected via Openreach GEA (FTTC and FTTP)
• The Residential Gateway will support
– IPoE for multicast traffic and PPPoE for BB traffic
– VLAN tag ID of 0 or no VLAN tag ID for multicast and BB traffic
• Fork IGMP requests for sending up multicast and BB paths. More details on the
support of Multicast via Openreach GEA (FTTC and FTTP) including features such
as fast leave are described in SIN 503 [6]
The BRAS will adjust the rate of the PPP session on a receipt of an IGMP join/leave by an
amount equal to the bandwidth of the channel specified in the join/leave.
• The BRAS will respond to IGMP joins/leaves after a configurable delay with a
default setting of 1s.
The BRAS will send IGMP queries independently of the Openreach GEA equipment
• The BRAS will send periodic IGMP queries over the PPPoE session
– General queries will be sent at a default interval of 125s with a default
maximum response time of 10s
– The BRAS will use a “robustness variable” setting of 3 as default.
Settings for timer values and “robustness variables” may be adjusted in consultation with BT
Wholesale during trials.
5.3.2 End user connected to an MSAN (WBC copper)
For an end user connected to an MSAN (WBC copper)
• The Residential Gateway will support a dual VC architecture
– Accept TV Connect multicast traffic on ATM VP/VC 0/35 with IPoA and
broadband traffic on ATM VP/VC 0/38 with PPPoA
– Fork IGMP requests for sending up multicast and broadband paths
• The MSAN will send periodic IGMP queries
SIN 511 Issue 3.1 British Telecommunications plc Page 18 of 23
– General queries will be sent at a default interval of 125s with a default
maximum response time of 100s.
– Specific queries will be sent at a default interval of 10s with a default
maximum response time of 8s.
The MSAN will use a “robustness variable” setting of 2 as default.
The MSAN will support the fast leave mode of IGMP.
5.3.3 ISP utilising the L2TP handover service option for WBC
For an ISP utilising the L2TP handover service option for WBC, the ISP will be expected to
provide similar IGMP aware line shaping functionality to that of the BT BRAS.
The ISP LNS will adjust the rate of the PPP session on a receipt of an IGMP join/leave by an
amount equal to the bandwidth of the channel specified in the join/leave.
• The ISP LNS will respond to IGMP joins/leaves after a configurable delay with a
default setting of 1s.
The ISP LNS will send IGMP queries independently of the MSAN
• The ISP LNS will send periodic IGMP queries over the PPPoA session
– General queries will be sent at a default interval of 125s with a default
maximum response time of 10s
– The LNS will use a “robustness variable” setting of 3 as default.
Settings for timer values and “robustness variables” may be adjusted in consultation with BT
Wholesale during trials.
SIN 511 Issue 3.1 British Telecommunications plc Page 19 of 23
6. Service Availability
Only a WBC customer (ISP) can take up the TV Connect service. The TV Connect service is
available to ISPs that take the WBC PTA (PPP termination and aggregation service) or L2TP
(Layer 2 tunnelling protocol) handover service.
An ISP can check the availability of Multicast at WBC exchanges by using the Broadband
Availability Checker available at http://www.btwholesale.com/ via the Routing and Planning
section under the Applications tab.
7. ISP Responsibilities
The ISP will be responsible for End User engagement, including client management (e.g. client
streaming, updates, and problem resolution)
The ISP specified Set Top Box will need to be capable of receiving TV Connect Streams,
decryption, and error recovery via retransmission.
The ISP will be responsible for the encoding and Conditional Access for their TV Channel
content.
The ISP will be responsible for connectivity to the TVC Head End up to the agreed handover
port in the MIP.
The ISP will be responsible for live streaming the TV Channel content into the TVC Head End.
The ISP will be responsible for the Residential Gateway (home router) and set top box
functionality within the end user’s environment. The Residential Gateway (home router) will
proxy IGMP requests upstream onto the TV Connect path and into the Broadband PPP path
towards the BRAS.
The ISP will participate in collaborative testing to support BT Wholesale with provision and
repair of the TVC service.
The ISP will ensure that all technical details required to complete the CRF are provided.
The ISP will be responsible for packet repair via Retransmission.
For an ISP that takes the L2TP handover service the ISP will be responsible for IGMP aware
PPP session shaping functionality.
SIN 511 Issue 3.1 British Telecommunications plc Page 20 of 23
8. References
Protocol Standards:
[1] IGMPv3 IETF RFC 3376 Internet Group Management Protocol Version3
http://datatracker.ietf.org/doc/rfc3376/
[2] MPEG2 – TS ETSI TS 102 034 (V1.4.1): “Digital Video Broadcasting (DVB);
Transport of MPEG-2 TS Based DVB Services over IP Based
Networks”.
[3] TR101 Technical Report DSL Forum TR101 Migration to Ethernet based
DSL Aggregation April 2006– section 6 Multicast
[4] Gigabit Ethernet IEEE http://www.ieee802.org
IEEE 802.3ab – 1000BASE-T
IEEE 802.3z – 1000BASE-X
IEEE 802.3ae – 10GBASE-x
[5] SIN 472 BT Wholesale Broadband Connect (WBC) Products Service
Description
http://www.btplc.com/sinet/ https://www.bt.com/about/sinet
[6] SIN 503 Generic Ethernet Access Multicast, Service and Interface
Description
https://www.bt.com/about/sinet
SIN 511 Issue 3.1 British Telecommunications plc Page 21 of 23
9. Abbreviations
21CN 21st Century Network
ATM Asynchronous Transfer Mode
AVC Advanced Video Coding
BB Broadband
BEA Broadband Edge Aggregator
BRAS Broadband Remote Access Server
BT British Telecommunications plc
BTW BT Wholesale
CA Conditional Access
CAT5 Category 5 cable
CPE Customer Premises Equipment
CRF Customer Requirements Form
DSL Digital Subscriber Line
DSLAM Digital Subscriber Line Access Multiplexer
DTT Digital Terrestrial TV
DVB Digital Video Broadcast
EAD Ethernet Access Direct [Openreach]
EEA Ethernet Edge Aggregator
EES Ethernet Edge Switch
EMM Entitlement Management Messages
EU End User
FEC Forward Error Correction
FTTC Fibre To The Cabinet
FTTH Fibre To The Home
GE Gigabit Ethernet
GEA Generic Ethernet Access (Openreach product)
HD High Definition
HE Head End
IEA Inner Ethernet Aggregator
IEEE Institute of Electronic and Electrical Engineers
IETF Internet Engineering Task Force
IGMP Internet Group Management Protocol
IP Internet Protocol
IPoA IP over ATM
IPoE IP over Ethernet
ISP Internet Service Provider
ITU International Telecommunications Union
SIN 511 Issue 3.1 British Telecommunications plc Page 22 of 23
L2S Layer 2 switch
L2TP Layer 2 Tunnelling Protocol
LFE Low Frequency Effects (Channel used in surround sound)
LAC L2TP Access Concentrator
LNS Layer Two Network Server
MIP Multicast Ingest Point
MPEG2 Motion Picture Experts Group compression algorithm
MSAN Multi-Service Access Node
MSIL Multi-Service Interconnect Link
OSS Operational Support System
PON Passive Optical Network
PPP Point-to-Point Protocol
PPPoA Point-to-Point Protocol over ATM
PPPoE Point-to-Point Protocol over Ethernet
PTA Point to Point Termination and Aggregation
RET Retransmission (packet repair)
RFC Request For Comment
RG Residential Gateway
s Seconds
SD Standard Definition
SIN Supplier Information Note
SMPF Shared Metallic Path Facility
SMPTE Society of Motion Picture and Television Engineers
SPTS Single Programme Transport Stream
STB Set Top Box
STIN Supplier Trial Information Note
TV Television
TVC TV Connect
UDP User Datagram Protocol
UHD Ultra High Definition
VC Virtual Circuit
VLAN Virtual Local Area Network
VP Virtual Path
WBC Wholesale Broadband Connect
SIN 511 Issue 3.1 British Telecommunications plc Page 23 of 23
10. History
Issue Date Changes
STIN 1.0 13th January 2012 First Issue for Publication on http://www.sinet.bt.com
STIN 1.1 14th September 2012 STIN updated to reflect learning from Product Trials
SIN 1.0 18th December 2012 STIN raised to SIN
SIN 1.1 25th January 2013 SIN updated to clarify availability of TV Connect over WBC
Copper
SIN 1.2 26th March 2013 SIN updated to include L2TP handover option
SIN 1.3 25th July 2013 SIN updated to include alternative Head End trial and
clarification to audio description options
SIN 1.4 10th October 2013 SIN updated to include channel resilience via alternative
Head End as firm option
SIN 1.5 7th November 2013 SIN updated to include additional information on channel
capacity management and service availability
SIN 1.6 9th May 2014 SIN updated to include option for SDI egress connection
from Head End
Change of SINet site references from
http://www.sinet.bt.com to http://www.btplc.com/sinet/
SIN 1.7 23th July 2015 SIN updated to include UHD channel Specifications
SIN 1.8 SIN Updated to extend TVC offering to incorporate options
to ingest pre-encoded (ISP encoded) content. 16/10/2015.
Reviewed and updated 29/10/2015.
SIN 1.9 November 2016 SIN updated to extend TVC offering to support the ingest of
Audio Description Broadcaster Mix for encoding to delivery
an alternative Audio Description format to Receiver Mix.
Minor editorial updates for clarity on specification.
SIN 1.10 October 2017 TV Connect Protect option withdrawn.
Minor editorial updates to clarify diagrams.
Removed invalid example of product option from section 5.
SIN 2.0 December 2017 Withdrawal of the encoding capability of TV Connect.
Documentation correction to requirements of End User
connectivity to MSAN WBC Copper (section 5.3.2)
SIN 3.0 December 2019 Added support for 10Gbps interfaces and duplication of
multicast traffic back to ISP
SIN 3.1 July 2020 Change SINet site references from
http://www.btplc.com/sinet/ to
https://www.bt.com/about/sinet
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