[PPT] - Access networks Services Department of Budapest University of PowerPoint Presentation

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Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

Access networks – Services

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BME-TMIT

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What services? - Triple Play

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BME-TMIT

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Triple Play – economical reasons

Triple Play service Architecture

Voice/data inflection point Internet > Voice => Best Effort (WWW) Video inflection point Video+VoIP > Best Effort => Triple Play architecture

Source: Alcatel

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BME-TMIT

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Convergence

Service convergence
Device convergence
Network convergence

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BME-TMIT

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The network convergence

IMS Home environment Mobile environment Office environment Provider Network

One provider- everywhere

 Common services  Common profile  Common billing

Beneficial for

 Provider  User

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BME-TMIT

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Changing Trends

Fixed line based services are decreasing
Mobile users are increasing despite that penetration is high
Broadband Internet installations are increasing

Broadband Mobile Fixed

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BME-TMIT

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Convergence of operators

Voice Data Video (TV) Mobile Telecom



Cable



Mobile



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BME-TMIT

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Video services

IPTV – Broadcast
SDTV
HDTV
Typical implementation: Multicast
VoD – Video on Demand
Bandwidth depends on content quality
Typically unicast
Other services (Time-shift, etc) – do not

represent different requirements

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BME-TMIT

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Video service architecture

Aggregation STB HGW ADSL2+

r VDSL

DSLAM TV Source Video Server Edge Router

Home network First Mile (DSL) Ethernet aggregation

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BME-TMIT

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VoD vs. IPTV

A VoD service requires higher bandwidth!
IPTV broadcast, 300 channel bandwidth demand
300 MPEG-2 channel, 1.5Mbit each =~1Gigabit
VoD bandwidth demand – depends on # of users
20000 user 10%-os peak usage =~7.5Gbps
The IPTV is more important – priority over the VoD
High availability => overprovisioning, protection

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BME-TMIT

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Voice services - VoIP

VoIP – cost effective
The HGW has gateway function or IP phone is

required

Service convergence
VoIP protocols
IP, TCP, UDP (User Datagram Protocol)
RTP (Real Time Protocol), RTCP (Real Time

Control Protocol)

SIP (Session Initiation Protocol), H.323 (ITU-T)

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BME-TMIT

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VoIP service architecture

PSTN

Aggregation HGW ADSL2+

r VDSL

DSLAM Edge Router Soft- switch

Home network First Mile (DSL) Ethernet aggregation

Coding, framing, queuing

Jitter buffer Transport Buffering Decoding

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BME-TMIT

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Data communication- HSI

Typical usage
Internet access
VPN access
Requirements
Best Effort
1.5-2 Mbps usually enough

– Except heavy p2p

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BME-TMIT

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HSI service architecture

Internet

Aggregation HGW ADSL2+

r VDSL

DSLAM BRAS PC

PPPoE

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BME-TMIT

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Triple-Play network requirements

Video
Low delay, low jitter, no loss
High bandwidth
Effective broadcast/multicast

mechanism

VoD scalability
Below 1 sec recovery
Voice
Low delay and Jitter
Low loss
Sub-second recovery in case of

failure

HS Internet
Guaranteed bandwidth
Possible bursty tranfer
Business users
Guaranteed bandwidth
Low packet loss ratio
50ms protection
General
Good cost/performance ratio
Signaling support
Network – service cooperation
Support for resilient architecture

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Budapest University of Technology and Economics Department of Telecommunications and Media Informatics

Generic service architectures

Access network-

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BME-TMIT

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Service Architecture

HSI Voice Video

Internet

STB RGW DSLAM Video Server Source SoftSwitch PBX STB RGW Coax DSL

?

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BME-TMIT

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Ethernet in the MAN

Large scale deployment anticipated
MAN - Metro Ethernet
First mile: EPON, GPON
„Carrier grade” requirements:
Scalability: many thousands of users
Restoration, protection: high availability required (5x9),

50ms

Service management (OAM)
QoS support: SLA, guarantee
Security
Ethernet based services
Standardization in progress

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BME-TMIT

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Standardization

MEF: services – from user perspective
ITU-T: services – from network perspective,

restoration and protection

IEEE: Higher level functions: Ethernet OAM,

provider bridges, EPON

IETF: Ethernet over MPLS (Ethernet wire) és

VPLS (Virtual Private LAN Service)

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BME-TMIT

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Single-Edge architecture

HSI Voice Video

Internet

STB RGW DSLAM Video Server Source SoftSwitch PBX STB RGW Coax DSL

PPPoE

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BME-TMIT

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Single Edge - 2

Old fashioned architecture
PPPoE tunnel to the BRAS
Strengths
Authentication
Traffic containment
Security
Drawbacks
Multicast is not possible

– Big disadvantage for IPTV!

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BME-TMIT

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Multi-Edge architecture

HSI Voice Video

Internet

STB RGW DSLAM Video Server Forrás SoftSwitch PBX STB RGW Coax DSL BRAS BNG

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BME-TMIT

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Multi-Edge architecture- 2

Internet access still uses PPPoE
Internet access through the BRAS
VoIP and Video uses IPoE
IP address by DHCP
Service access through BNGs
Advantages
Multicast possibility
Less overhead
Lower load at the BNG

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BME-TMIT

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IPoE and PPPoE

PPPoE – Point to Point Protocol
Authentication: user/pass, line ID
PPP tunnel ends in the BRAS
Connection oriented
Not all devices support
IPoE – DHCP
Authentication: MAC addr, +DHCP option line ID
„flat rate online”
Connectionless, Multicast is possible
All devices support

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BME-TMIT

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PPPoE overhead

PPPoE
Two level L2

encapsulation

10 byte overhead for

each packet

PPPoE supports only

point-to-point

IPoE
Fancy name for the

basic IP/Ethernet encapsulation

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BME-TMIT

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IPoE and PPPoE : requirements

In both cases the authentication can be done at the

DSLAM

PPP termination is required at the DSLAM
PPPoE
PPPoE intermediate agent is required to add additional

information to PPPoE packets

IPoE
DHCP option 82 for line identification
DHCP relay agent to convert DHCP request to unicast

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BME-TMIT

Definitions Auto configuration and AAA

Autoconfiguration: process of establishing a connection AAA

Authentication

– process of determining whether someone or something is, in fact, who or what it is declared to be. – based on identifiers and security attributes. – part of an actual access to a network/service in the context of a SLA or contract, and often is linked with a fee (Accounting)

Authorization

– process of giving individuals access to system objects based on their identity.

Accounting

– recording, classifying, summarizing, and interpreting of events of a financial character in a significant manner

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BME-TMIT

Autoconfiguration: PPP model

Characteristics :
PPP = Point-to-Point Protocol
PPP session performs (between CP modem - PPP peer)

– Link establishment (LCP packets) – Authentication (optional, PAP or CHAP) – Network-layer protocol (NCP packets : eg IPCP: CP gets its IP@)

PPP encapsulation stays during session
Origin of PPP for Internet Access via voice band

modems (fig.)

Continued to be used in DSL

PSTN Internet RAS Modem Modem bank

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BME-TMIT

PPPoE

PPPoE needed when PPP transported over Ethernet: allows

– transport over shared medium – PPP session multiplexing

Autoconfig Procedure :
Detection of server(s):

PPPoE Active Discovery Initiation (PADI)

Server(s) reply :

PPPoE Active Discovery Offer (PADO)

Choice of server :

PPPoE Active Discovery Request (PADR)

Server confirmation :

PPPoE Active Discovery Session-confirmation (PADS)

PPP IP PPPoE 802.3 MAC PPP IP PPPoE 802.3 MAC RFC 2684 AAL5 ATM PPPoE PPPoEoA

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BME-TMIT

PPPoE initialisation

PPPoE Client

<PADI>

Ethernet:

DA: Broadcast
SA: User MAC@

PPPoE:

ISP-Name

Modem Terminator Access Node Ethernet Switch PPPoE Server in Edge Node

<PADI>

Ethernet:

DA: Broadcast
SA: User MAC@

PPPoE:

<PADI>

Ethernet:

S-VLAN ID
(C-VLAN ID)
DA: Unicast/Multicast
SA: User MAC@

PPPoE:

<PADI>

Ethernet:

S-VLAN ID
(C-VLAN ID)
DA: Unicast/Multicast
SA: User MAC@

PPPoE:

<PADO>

Ethernet:

S-VLAN ID
(C-VLAN ID)
DA: User MAC@
SA: Server MAC@

PPPoE:

<PADO>

Ethernet:

S-VLAN ID
(C-VLAN ID)
DA: User MAC@
SA: Server MAC@

PPPoE:

<PADO>

Ethernet:

DA: User MAC@
SA: Server MAC@

PPPoE:

<PADO>

Ethernet:

DA: User MAC@
SA: Server MAC@

PPPoE:

<PADR>

Ethernet:

DA: Server MAC@
SA: User MAC@

<PADR>

Ethernet:

DA: Server MAC@
SA: User MAC@

<PADR>

Ethernet:

S-VLAN ID
(C-VLAN ID)
DA: Server MAC@
SA: User MAC@

<PADR>

Ethernet:

S-VLAN ID
(C-VLAN ID)
DA: Server MAC@
SA: User MAC@

ISP-Name
ISP-Name
ISP-Name
ISP-Name
ISP-Name
ISP-Name
ISP-Name

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BME-TMIT

Autoconfiguration : DHCP model

Characteristics :
DHCP = Dynamic Host Configuration Protocol
DHCP works in client/server mode
DHCP is carried over IP, only during config phase
DHCP session (host - server) :

– delivers host-specific config parameters – allocates NW addresses to host

automatic : permanent IP@
dynamic : leased IP@ (limited time)
manual
Autoconfig procedure :
Discovery of DHCP server

(DHCPDISCOVER)

Replies of server(s)

(DHCPOFFER)

Host selects server

(DHCPREQUEST)

Server acks and sets config

(DHCPACK)

DHCP IP 802.3 MAC Config Data IP 802.3 MAC

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BME-TMIT

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Mac Forced Forwarding

DSLAM only sends to BNG
All other dropped
Operation:
PPP: sends to BRAS only
IPoE:

– ARP request results in BNG address always – Packets sent to other destinations dropped

Can also be done with VLANs

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BME-TMIT

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PPP intermediate agent

STB RGW DSLAM DSL BRAS

RADIUS

PPPoE PPPoE+VSA RADIUS+NAS port ID

DSLAM adds to PPPoE

DSL line ID
DSLAM ID

DSLAM acts as PPPoE relay The PPPoE relay adds PPPoE line and DSLAM ID in PPPoE VSA The BRAS forwards the information as NAS Port ID

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BME-TMIT

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DHCP option 82

STB RGW DSLAM DSL DHCP server

RADIUS

DHCP req DHCP req + option 82 RADIUS+NAS port ID

DSLAM adds to DHCP req Option 82

A DHCP 82 option contains:

 DSLAM ID, DSLAM port ID  PVC  Or any other information such phone number

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BME-TMIT

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QoS

End-to-end
From user to Video/VoIP server

– In fact to the BNG

Possible bottlenecks
First mile
Ethernet Aggregation
Regional IP core
The interworking between technologies is required

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BME-TMIT

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QoS support

Priority based on 802.1Q VLAN tag
3 bit = 8 classes
The priority bits described in 802.1p
VLAN priority and IP TOS are similar
Not all switches support 8 classes
P-bits are in VLAN header, but not associated to the ID

VLAN ID (12 bit) 802.1p (3 bit) CFI (1 bit) 802.1Q VLAN TAG

P-bits

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BME-TMIT

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Multicast

Very important in case of broadcast video
Support needed in aggregation too
In case of PPPoE it is not possible
Except if the PPPoE is terminated at DSLAM
If it terminates at the BRAS, each user gets in

Unicast from BRAS

Possible with IPoE
Support needed: IGMP snooping
The DSLAM can be IGMP proxy

– Lower load on the multicast router

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BME-TMIT

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Metro Ethernet Architecture

Metro Backbone

National IP Network

GE

Aggregation Switch

2 x GE GE GE

VOD Server

TV Headend

3rd Party ISP

VOD Server VOD Server

POP

B-RAS Router

Internet

E.PON EFM G.PON 100BaseFX B.PON GE GE GE GE

Location Server

SIP Proxy Server

Triple Play implementation

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BME-TMIT

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Optimal network utilization

Different solution for each service
Video
Multicast, low statistical multiplexing

– Possible gain since video is VBR, with many channels

VoIP
Call level statistical multiplexing

– Erlang formulas help in dimensioning

HSI
Packet level statistical multiplexing

– Multiple models exist, e.g. Guérin

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BME-TMIT

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Thank You for your attention!
Questions?