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Brussels, 31 May 2011 Giovanni Santella
The role of multicast bitstream in
promoting competition in triple play
Giovanni Santella
Interconnection and Wholesale Services Division
AGCOM
Brussels, Hotel Châtelain, 31 May 2011
Brussels, 31 May 2011 Giovanni Santella
Content
1) Bitstream regulation in Italy
2) Wholesale multicast: the service model
3) Wholesale multicast: the architecture
4) Wholesale multicast: the protocols
5) Final comments
Brussels, 31 May 2011 Giovanni Santella
Bitstream regulation in Italy (1)
Agcom resolution n. 731/09/CONS, has confirmed the obligation for Telecom Italia (SMP in MK 4 and 5) to provide a Bitstream reference offer both on copper and fiber access network. Bitstream offered on NGAN to be defined with a separate proceeding.
Recent Decision n. 301/11/CONS concerning NGA regulation starts a public consultation and proposes an architecture for bitstream offered on NGAN.
Brussels, 31 May 2011 Giovanni Santella
Bitstream regulation in Italy (2)
1. Bitstream on copper access network was adopted in
november 2007 (replaced previous wholesale ADSL offer,
based on retail minus).
2. Bitstream is offered both on ATM and Ethernet layer 2
transport protocols.
3. Access and backhaul prices are cost oriented.
4. Available both as naked and shared bitstream models.
Brussels, 31 May 2011 Giovanni Santella
Bitstream regulation in Italy (3)
3 levels of interconnection
• DSLAM IC;
• parent node IC
• distant node IC
One parent Node allows the provision of retail
services in 1 out of 30 areas that cover the whole
national territory;
ATM Bitstream
Brussels, 31 May 2011 Giovanni Santella
ETHERNET
Bitstream regulation in Italy (4)
ETHERNET
Local
Exchange
DSLAM
Building
CPE
OLO
Feeder distant (~ 30) Feeder parent (~ 400)
Access Backhaul service Second level transport
Ethernet Bitstream
Brussels, 31 May 2011 Giovanni Santella
Bitstream regulation in Italy (7)
1. Agcom resolution n. 301/11/CONS: starts a public consultation
2. Defines the provision of bitstream also on fiber FTTx.
3. Ethernet based.
4. Three interconnection levels: Local exchange, parent node
(200), distant node (30).
Bitstream on NGAN
Brussels, 31 May 2011 Giovanni Santella
Wholesale multicast:
the service model (1)
1. Telecom Italia, according to current regulation, has to provide multicast
functionality within its Ethernet bitstream reference offer.
2. Wholesale Multicast IP service allows AAOs, that are interconnected to
one of the 30 Ethernet macro-area nodes, di distribute multicast
channels to their customers using Telecom Italia access network.
3. This service allows AAOs to replicate IPTV Telecom Italia offers.
4. Some issues of the offer: bandwidth allocation, routing of packets and
control plane are managed at IP level. IP multicast packets are
transported inside Ethernet frames using specific VLANs dedicated to
multicast. IP multicast protocol ensures an efficient bandwidth use
through optimization of the replicas of traffic flows in each network
segment.
Brussels, 31 May 2011 Giovanni Santella
Multicast flows are distributed on Telecom Italia’s network only if they’re required by
OLO’s customers. In this case they are replicated, for each customer, only in the
final access segment (DSLAM – copper – customer’s site) according to customer
requests
Wholesale multicast:
the service model (2)
Brussels, 31 May 2011 Giovanni Santella
• Wholesale provision of multicast requires:
1. AAOs customer terminals support IGMP protocol: deals with signalling
between host and network for the request or interruption of the reception
of a multicast channel;
2. AAOs IC interface supports PIM-SSM (Protocol-Independent Multicast-
Source Specific Multicast): enables the routing of a defined channel
(identified by an IP multicast address) from a specific source to the
customer who requested it;
3. IP multicast addressing plan is managed by Telecom Italia to ensure
uniqueness of addresses and network integrity (correct end-to-end
routing of the channels and protection from overloading phenomena)
4. Sources unicast addresses (IPv4) are public.
Wholesale multicast:
the service model (3)
Brussels, 31 May 2011 Giovanni Santella
Head
End
SP B
SiSi
SiSi
SiSi
IP
IGMP Snooping
& Proxy reporting
Head
End
IP
SP A
In downstream the
multicast channel is
mapped to the line from
which the IGMP request
has been received
NT
NT
DSLAM
IP multicast contents of SP_X is transported at IP
level to the Feeder connected to the relevant
DSLAM, according to IGMP requests coming
from such DSLAM.
IP
STB SP_A
STB SP_B
Wholesale multicast: the architecture (1)
Brussels, 31 May 2011 Giovanni Santella
OPM
OPB
VRF 1
VLAN Video
• An IGMP client is installed in the ISTB and allows to send requests of multicast channels to the
DSLAM
• DSALM duplicates video channels towards customers who have required
• DSALM forwards to feeder the request of a new channel or the last request to interrupt the
reception of a given channel by a customer
• The Feeder performs IP multicast routing. Duplicates towards the DSLAM only channels
required through IGMP. Requires multicast channels using the PIM protocol.
Feeder Metro
CPE
STB TI
PVC 8/36
PVC 8/35
BRAS
VLAN Alice Protocol Filtering
PPPoE > VLAN Alice
IPoE > VLAN Video
PIM Routing multicast
IS&P IGMP Snooping con Proxy Reporting
IR IGMP Routing
IS&P IR PIM PIM
IGMP
IGMP proxy
HEAD END
Server
VOD
DHCP-Server
Wholesale multicast: the architecture (2)
Brussels, 31 May 2011 Giovanni Santella
IP multicast international reference standars
1. PIM-SSM: RFC 4601 “Protocol Independent Multicast – Sparse Mode (PIM-SP)”
2. IGMPv2: RFC 2236 “Internet Group Management Protocol, Version 2”
3. BGP: RFC 1771, RFC 4271 “A Border Gateway Protocol 4 (BGP-4)”
4. MP-BGP: RFC 2858, RFC 4760 “Multiprotocol Extensions for BGP-4”
Wholesale multicast:
the architecture (3)
Brussels, 31 May 2011 Giovanni Santella
1. AAO Physical Interconnection interface: GbE port.
2. At the interconnection interface the OLO sends its multicast IP
packets with TOS and CoS fields marked with the value “3” .
3. IP multicast packets are transported within Telecom Italia’s
ethernet network on a VLAN, dedicated to multicast, with CoS = 3
Wholesale multicast:
the architecture (4)
Brussels, 31 May 2011 Giovanni Santella
Multicast Service activation (1)
• The OLO provides the incumbent with the following information
1. Mapping scheme between IP multicast addresses and channels.
These IP addresses were previously assigned by Telecom Italia
2. Nominal bandwidth (B) associated to each channel
3. IP address of the source of the multicast channels
4. DSLAMs where the OLO intends to provide TV services
5. Maximum required backhaul bandwidth in the segment DSALM-feeder node
6. The identifiers of the activated customers (identifies the ADSL line that join the service)
Brussels, 31 May 2011 Giovanni Santella
Multicast Service activation (2): current
requirements
• Maximum 1024 channels managed for each macro-area
• IP bandwidth/OLO at the IC = max number of channes*B
• Copper line and ADSL profile are able to support the
maximum required bandwidth
Brussels, 31 May 2011 Giovanni Santella
Authentication and admission
control
OPM
OPB
DHCP-Server
(working)
Default Gateway
Gateway IP
VLAN Video
DHCP
• The STB requires a dynamic IP address via DHCP (DHCP client)
• The DSLAM supports “DHCP Relay Agent” functionality
• “Conditional Access” and “Admission Control” implemented for each ADSL2+ access: the
IGMP request is forwarded to the feeder if 1) the required channel belongs to the bouquet
of the SP_A, 2) is not exceeded the total bandwidth set on the ADSL2+ port.