The role of multicast bitstream in promoting competition ... · The role of multicast bitstream in promoting competition in triple play ... IPoE > VLAN Video ... • The DSLAM supports

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

[email protected]

Brussels, Hotel Châtelain, 31 May 2011


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


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.



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.



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


ETHERNET


ETHERNET

Local

Exchange

DSLAM

Building

CPE

OLO

Feeder distant (~ 30) Feeder parent (~ 400)

Access Backhaul service Second level transport

Ethernet Bitstream



Ethernet service model



Protocol stack



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


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.


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 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.




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)


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)


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”


the architecture (3)


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


the architecture (4)


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)


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


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.


Final comments

• Multicast Telecom Italia offer is under approval by

AGCOM

• Main issues: costs, protocols, Telecom Italia

requirements

• OLOs are not yet using it for retail IP-TV offers

Thank you for the attention

Documents

The role of multicast bitstream in promoting competition ... · The role of multicast bitstream in promoting competition in triple play ... IPoE > VLAN Video ... • The DSLAM supports