Transcript Deploying Instant Messaging - Ferdowsi University of Mashhad
Modern Services of Data Network
Part I Communication
Presented by: Dr. Mohsen Kahani Ferdowsi University of Mashhad [email protected]
http://www.um.ac.ir/~kahani
Table of Contents
Ethernet and 10GBE Internet Telephony WiFi Hotspot xDSL Technology Fiber To The Home (FTTH)
Backbone Architecture Layers
Network designs are made up of three technology layers:
The
access layer
which is the technology used in LANs
The
distribution layer
together connects LANs
The
core layer
connects different backbone networks together
Backbone Technologies
Fiber
Distributed
Data Interface (FDDI)
FDDI backbone protocol was developed in the 1980s and popular during the 80s and 90s.
FDDI operates at 100 Mbps over a fiber optic cable.
FDDI uses both a physical and logical ring topology capable of attaching a maximum of 1000 stations over a maximum path of 200 km. A repeater is need every 2 km.
FDDI’s future looks limited, as it is now losing market share to Gigabit Ethernet and ATM.
FDDI Topology
FDDI’s Self-healing Rings
Asynchronous Transfer Mode (ATM)
Asynchronous Transfer Mode (ATM) (also called cell relay) is a technology originally designed for use in wide area networks that is now often used in backbone networks.
ATM backbone switches typically provide point-to-point full duplex circuits at 155 Mbps (total of 310 Mbps).
Ethernet Timeline
1973 Ethernet Invented 2.93 Mbps
1992 10 Mbps Ethernet Available
1994 100 Mbps Ethernet Available
1997 1000 Mbps Ethernet Available
2002 10 Gbps Ethernet
FAST ETHERNET
Fast Ethernet refers to a set of IEEE 802.3 specifications that provide a low cost Ethernet-compatible LAN operating at 100 Mbps.
Basic idea is to keep all the old packet formats and protocols, just increase the speed.
Specifications:
100BASE-T4 : 100 Mbps over twisted pair category 3 UTP
100BASE-TX: for category 5 UTP, full duplex at 100 Mbps.
100BASE-FX: 100 Mbps.
for fibre, full-duplex at
GIGABIT ETHERNET
Fast is never fast enough
Migration of fast Ethernet to the desktop created bottlenecks at servers and switches.
Gigabit Ethernet was designed to alleviate this congestion by providing faster backbone technology.
The strategy for Gigabit Ethernet is the same as for fast Ethernet
GIGABIT ETHERNET – CONT.
Define a new medium, but retain the same CSMA/CD protocol and frame format as 10 Mbps and 100 Mbps Ethernet.
The transmission medium is optical fibre over short distances.
UTP and STP are also allowed.
Gigabit Ethernet Terminology
1000BASE-SX
Short wavelength specification for Gigabit over MMF up to 300 meters 1000BASE-LX
Long wavelength specification for Gigabit over MMF up to 550 meters or SMF up to 5 Km 1000BASE-CX
Short haul specification for Gigabit over 4 conductor coax up to 25 meters 1000BASE-T
Standard that can yield 100 meter distances
What’s new: 10 GbE
Formally ratified on June 12, 2002 Ongoing need for more bandwidth Designation of bandwidth Uses 802.3ae
40 GbE on its way
10 GE: a new Ethernet
10 GE – designed from the beginning for access to long haul networks
40 km maximum distance specified by the standard …
1550nm lasers
: optical amplifiers can be used to increase distance over dark fibre
State of the art: 250 km demonstrated in Denmark by the EU ESTA project
The 10 GE WAN PHY
10GE introduces a gateway from LAN to the WAN by means of the WAN PHY
Compatible with existing WAN infrastructure
Transmission rate
Encapsulation
Partial use of the management bits of the SONET/SDH frame
Today’s WAN PHY modules use SONET compliant optical components Router OC192
traditional
LTE 3R LTE
OC192 Router
3R 3R LTE LTE WAN
WAN PHY
novel
WAN PHY 10GE switch/router 10GE switch/router
Why native Ethernet long haul?
More than 90% of the Internet traffic originates on an Ethernet LAN Data traffic on the LAN increases due to new applications Ethernet services with incremental bandwidth offer new business opportunities to carriers
See IEEE Communications Magazine, Vol. 42, No. 3, March 2004, on additional benefits for both the enterprise and the service providers
Why not native Ethernet ?
Scalability, reliability, service guarantees …
All of the above are active research areas
Native Ethernet long haul connections can be used today as a complement to the routed networks, not as a replacement
Demo during ITU Telecom World '03
Intel Itanium-2 Intel Xeon Ixia 400T 10GE WAN PHY 10GE LAN PHY OC192c Force10 E 600 Ottawa Cisco ONS 15454 Cisco ONS 15454 Cisco ONS 15454 Toronto Chicago Cisco ONS 15454 Amsterdam Cisco ONS 15454 Force10 E 600 Geneva
10 GE WAN PHY over an OC-192c circuit using lightpaths provided by SURFnet and CANARIE 9.24 Gbps using traffic generators 6 Gbps using UDP on PCs 5.65 Gbps using TCP on PCs
HP Itanium-2 HP Itanium-2 Ixia 400T
Results on the transatlantic 10 GE
Single stream UDP throughput Single stream TCP throughput •Data rates are limited by the PC, even for our memory-to-memory tests •UDP uses less resources than TCP on high bandwidth-delay product networks
WAN PHY over DWDM
HP Itanium-2 10GE LAN Intel Xeon Ixia 400T Force10 E600 10 GE WAN DWDM 10 GE WAN Force10 E600 Ixia 400T 10GE LAN HP Itanium 2 DWDM Amsterdam Geneva HP Itanium 2
Direct lambda access from the provider is required The DWDM transceiver card as “LTE”
10GBASE-T Objectives
Keeping it Ethernet
Preserve the 802.3/Ethernet frame format at the MAC Client service interface Preserve min. and max. frame size of current 802.3 Std.
Support star-wired local area networks using point-to-point links and structured cabling topologies
Keeping it 10 Gigabit Ethernet
Support full duplex operation only Support a speed of 10.000 Gb/s at the MAC/PLS service interface
Compatibility with 802.3
Support Clause 28 auto-negotiation To not support 802.3ah (EFM) OAM unidirectional operation Support coexistence with 802.3af (DTE Power via Ethernet)
10GBE Applications
10GBE-T Importance
Faster network link speeds provide new generation of systems
Modular switches and servers
Backplanes and switch fabrics aggregate to support multiple 10GBASE-T ports Servers with faster I/O subsystems (i.e. PCI Express™) Low cost solutions are market stimulus
10GBASE-CX4 is a step in the right direction, but limited reach 10GBASE-T:
Addresses PHY costs concerns in Enterprise market
Enhances reach and conforms to structured cabling environments Lower cabling costs
Installation practices are well-known Ease of installation Cost of termination
Comparison of 10GBE & GBE
10GBE-T Performance
With the 4 connector model and proposed signaling:
100m on Class F (Cat 7) > 55m on Class E (Cat 6) operating beyond the specified frequency range 100m on the new cabling being defined by cabling standards groups (derivative of Class E/Cat 6) 20 to 60m on Class D (Cat 5e) was discussed
Requires operation beyond the specified frequency range
No consensus achieved on extending the specification Increase in system margin and/or reach are possible:
–
Several techniques have been presented in the SG:
Analog signal conditioning
Alien noise suppression Improvements in the cabling specification
ATM vs. Switched Ethernet
ATM is a switched network, but differs from switched Ethernet in four ways: 1. ATM uses small, length.
fixed-length packets of 53 bytes (called cells). Ethernet frames are variable and can be up to about 1 kilobyte in 2. ATM provides user data. Switched Ethernet does error correction.
no error correction on the 3. ATM uses virtual channels instead of the fixed addresses used by traditional data link layer protocols such as switched Ethernet.
4. ATM prioritizes transmissions based on Quality of Service (QoS) , while switched Ethernet does not.
Enterprise Backbone Technology Trends
Organizations are moving to Ethernet based collapsed backbones with switched LANs or VLANs.
Gigabit Ethernet use is growing.
FDDI seems to be on its way out.
ATM, while still popular in WANs, is also losing ground to Gigabit Ethernet.
Taken together, it appears that Ethernet use will dominate the LAN and backbone.
The Ideal Backbone?
The ideal network design is likely to include the following characteristics:
Combined use of layer 2 and layer 3 Ethernet switches.
The access layer (LANs) uses 10/100 Layer 2 Switches running Cat 5 or Cat 6 twisted pair cables (Cat 6 enables the move to 1000BaseT).
The distribution layer uses Layer 3 Ethernet Switches that use 1000BaseT or fiber, Cat 6 or Cat 7 TP.
The core layer uses Layer 3 Ethernet Switches running 10GbE or 40GbE over fiber.
Reliability is also increased in the network by using redundant switches and cabling.
Internet Telephony
vs.
Telephony over Internet
Telephony over Internet
Emulation of Telephony Services on Internet
dumb end terminals (cable modems)
12-digit keypad UI
transparency of services
it is important!
Primary motivation
cost savings
non-telcos can enter
Cost savings are transient
Whats in it for customers????
Branch Office Application
Interoffice Trunking Application
Interoffice Trunking Application
. Interoffice Trunking Application
Internet Telephony What is it?
Use your PC as a telephone Motivation
Cost Advanced Services
Higher fidelity voice
3D voice reconstruction
Integration with calendar
Complex call management
Mobility
Powerful voicemail systems; integrated messaging
Multiparty calls
Video/whiteboard
Compression, silence suppression
Internet Telephony
Integrate telephony services with
web
instant messaging and presence
text chat
interactive games
voice Games IM Web Interactive Communications Email Presence Chat video INTERNET TELEPHONY
New Services
Integration causes
service multiplication
20 voice services X 20 web services = 400 integrated service possibilities
not all make sense
New services = revenue opportunities
Examples
IM Notify when busy
subscriber gets instant messages when friends telephones (IP or POTS) available
Call redirect to web
web page returned instead of busy signal
Web IVR
web page of menus, final choice rings phone
More Services
Shared web browsing
talk and browse jointly
Transfer to email
Caller is disconnected and mail tool pops up
Email call logs
Unanswered calls cause email notifications
IM notifications of conference join
On a conference bridge, instant message indicates participant joins/leaves
Web call-ID
web page of caller pops up when phone rings
Who can get services?
Advanced services can be offered to PSTN end systems too!
VXML consortium
technology for providing web content on phone
allows web services to be exposed
Speech to text
email sending
web browsing
IM
Text to speech
Instant messages
How to do it?
Integrated services = integrated server
SIP server/gatekeeper
SMTP/IMAP/POP client and server
Presence and IM server
Web access
Conference services access
Conference Services Mail Services Intelligent Integrated Communications Server Web Services IM and Presence Services Directory Services
What does it have to do with ISP’s?
IP telephony is point to point
Looks like data to ISP
Extra Services!
Network QoS support
Processing Services
Gateway Services
Database Services
IN Services
Gateway Services
IP to PSTN
PSTN to IP
PSTN to PSTN, IP long distance
IP to IP, PSTN long distance
GW
ISP NETWORK
PSTN GW
Gateway Services
IP to PSTN
Billing - accounts, credit cards, e-cash
Discovery - based on cost, proximity, codec/protocol support, administrator
Non-locality problem - partnerships; billing!
PSTN to IP
IP endpoint identification
IP address
Speech recognition
alphabet keys
telephone numbers
Telephone Numbers
International, area code, mixed, 10-XXX access
Gateway Selection
Gateway Services
IP-PSTN-IP (access bypass)
use ISP as LEC improved voice quality Discovery problem
Proximity of GW to IP address Traditional routing?
Phone connection
transcode for voice only?
Modem - IP links-on demand Billing
PSTN-IP-PSTN (long distance bypass)
Nearly identical to IP to PSTN case Selection of gateway similar to PSTN to IP case ISP can now be a long distance provider -
ITSP
Gateway Architecture
Basic HW Components
PC
DSP card Telephony card (Dialogic, Natural Microsystems) Ethernet card Gateways are a SOFTWARE problem
call control, billing, accounting, net protocols, management, etc.
T1, ISDN, analog PSTN CARD DSP CARD ETHERNET PC - WIN NT or UNIX CPU
Gateway Features
Codecs
GSM, G.729, G.723, Elemedia, G.728, G.726
Authentication/authorization Accounting Protocol compliance H.323, H.332, SIP Management Billing
credit cards, account, debit cards, phone cards, SET
$/port Telephony termination
analog, T1, T3, ISDN PRI IP termination
Ethernet, Frame Relay, T1,T3, ATM/SONET Routing
static, database access, polling IVR System User Profiles Bridging
Main Vendors
Lucent Technologies
Enterprise and Carrier grade gateways Vienna Systems VocalTech Micom NetiPhone Netspeak
PhoNet Ericsson Ascend ….. Several HUNDRED vendors Prediction:
Small players will lose to big, carrier-grade capable vendors
ITSP’s
Internet Telephony Service Providers
PSTN to PSTN, IP long distance Several business models:
Run gateways, resell service to service providers Run gateways and service; perhaps partner with other such providers, also resell service to telcos and small ISP’s Run service only, lease gateways from resellers Run clearinghouse for settlements and billing agreements (Planet Telecom)
Database Services - User Location
How to determine IP address of a person you wish to talk to
Dynamic IP addresses make this a very hard problem
Several approaches
Single database
Email-based
Location service provided by your ISP
User Location
Single Database
User “registers” with well-known database when logging in, “unregisters” when leaving
Registration binds a unique identifier (your name) to IP address
To call a person, you query database with identifier, and get IP address back Model used by H.323 (Gatekeepers) Initial model used by most IP telephony software - each software maintains its own listing Can have global directories - Four11 Big drawback - requires central directory for whole planet - scalable? Who will run it?
Email based
Your telephone address is your email address
You register with a directory server associated with your domain Other users find your directory server in DNS Can then query directory server to get your IP address Scalable, uses existing infrastructure; email names mnemonic (usually); portability; multiple names, single email and telephony identifier
Database Services - Voicemail
Your PC is not connected to Internet 24 hours per day Via Location Database, ISP knows when you are an are not connected - can provide voicemail service One method:
Location server directs caller to contact voicemail server; caller leaves message Location server sends you email with a URL When you log in, you click on URL - brings you to a web page on the voicemail server and gets a Java applet Applet lets you sort and file messages, play them out, forward, rewind, etc.
Big plus: Don’t even need IP telephony software for voicemail, just email!
IN Services
IN = Intelligent Networking
Existing technology which lets you create services in telephone network via direct control over switches Basic idea - let IP hosts (ISP servers) set up services in telephone network Examples
Click-to-dial
Click-for-faxback Click-for-content
IN Services
Click to Dial
Web page has link to call customer service department, and a form entry to fill in your phone number Click on link - web server instructs telephone switches to connect you to customer service Your phone rings, then customer service Call billed to company Click for faxback
Same as above, except your phone is a fax machine, and customer service phone is a fax bank
Gives you instant access to fax databases
Click for content
You wish to listen to an audio file over the telephone
Click on web page, fill in form with telephone number.
Media server (either in PSTN or on Internet) calls your telephone You control playback via telephone tones and/or PC controls
How to do it all?
Lots of protocols involved
RTP (Real Time Protocol) H.323 (ITU Spec for Multimedia Conferencing) SIP (Session Initiation Protocol) RTSP (Real Time Streaming Protocol) LDAP (Lightweight Directory Access Protocol) Lots still under development
Gateway Discovery IN Services User Location
RTP/RTCP
RTP provides for
Real time transport Resequencing Payload type identification Intra and Inter media synchronization Encryption Multicast
Per User demultiplexing - SSRC RTP does not
Provide QoS Require RSVP RTP is a framework
Specific payload formats defined for H.263, etc.
UDP Port numbers based on application
Real Time Control Protocol RTP port + 1 Used for
QoS Reporting
Sender reports: packets sent, bytes sent Receiver reports (per sender): loss, delay, jitter observed; instantaneous and cumulative Media Synchronization
NTP and RTP Timestamp correlation Loose Session Control
Hello, Bye messages SDES - email, username, CNAME, etc
H.323
Monstrous ITU Specification for Multimedia Conferencing H.323 is an umbrella - many sub-specifications:
H.225.0: Call control, RAS H.245: Capabilities Exchange, Indications, Notifications H.332 - Large Group conferences H.450 - Supplementary Services G.711, G.728, G.729, G.723.1 - speech coders H.261, H.263 - video coders H.246 - Interworking between H.323 and other H.XXX standards H.235 - Security for H.323 terminals
H.323 Elements
H.323 Terminal
PC with H.323 software MCU
Multipoint Control Unit Mixes audio and video MC
Multipoint Controller Performs signaling for centralized conferences MP
Multipoint Processor Actual device for mixing audio and video
Gatekeeper
Controls sessions Performs user location and registration Performs admission control Reroutes signaling Processes RAS (Registration, Admissions, Status) from H.323 terminals Gateway
Interface between H.323 systems and other systems - PSTN, H.324 (PSTN multimedia), H.320 (ISDN multimedia), H.321 (ATM multimedia)
H.323 in an ISP Network
GATEWAY TO PSTN MCU (MP and MC) ISP IP NETWORK GATEWAY GATEKEEPER POP-IN-A-BOX H.323 TERMINALS TO PSTN DATABASE STORAGE
Basic H.323 Call Flow
TCP SYN TCP SYN ACK H.225 SETUP H.225 CONNECT TCP SYN TCP SYN ACK CAPABILITIES/MASTER-SLAVE CAPABILITIES/MS-ACK/CAP-ACK CAP-ACK/MS-ACK/OPEN AUDIO OPEN ACK OPEN ACK/ OPEN AUDIO AUDIO DATA
Session Initiation Protocol
IETF Standard Lightweight multimedia session initiation, call control, capabilities exchange, and user location Based on http; textual, reuses authentication mechanisms Provides full telephony services: call forward, transfer, 800,900 style numbers Supports personal mobility Addressing based on email address Uses SDP (Session Description Protocol) for expressing capabilities
Basic methods:
INVITE - ask a user to join a session; callee responds with accept or reject, along with a slew of reason codes OPTIONS - obtain capabilities, but don’t invite CONNECTED - acknowledges acceptance BYE - for transfers and session terminations REGISTER - Allows a user to register with a SIP server
Wi-Fi Hotspot
A specific geographic location in which an access point provides public wireless broadband services to mobile visitors .
Hotspots are often located in heavily populated places such as airports , convention centers , coffee shops , hotels , and so on
HotSpot Motivation
an increasing trend toward being always on , always active , and always connected and delivering high-speed data and Internet applications to wireless subscribers
Wireless Taxonomy
Wireless WANs (WWAN)/Nomadic Networks
High power, long range Various cellular and related technologies (GSM, GPRS, CDPD, TDMA, etc.)
Wireless LANs (WLANs)
Medium power, medium range IEEE 802.11 and similar technologies
Wireless Personal Area Networks (WPANs)
Low power, short range Bluetooth, HomeRF, IrDA, IEEE 802.15 technologies PAL/ Hotspot Service
Standards – IEEE 802
Bluetooth/ IEEE 802.15
Derivation of Bluetooth 1.x spec and more meaningful standards for developments relate to Bluetooth applications profiles, operates at 2.4 GHz IEEE 802.11
Basic standard for WLANs which was developed in the late 1990s supporting speeds up to 2 Mbps IEEE 802.11b
IEEE 802.11a
Basic standard for WLANs. An extension of the IEEE 802.11 specifications, supporting speeds of 1, 2, 5.5, and 11 Mbps . Operates at 2.4 GHz High-speed WLAN supports 6, 12, and 24 Mbps (mandatory), 9, 18, 36, 48, and 54 Mbps (optional), operating at 5 GHz
Standards – IEEE 802 (cont’)
IEEE 802.11e
IEEE 802.11g
IEEE 802.11i
IEEE 802.16
IEEE 802.1x
Revision of 802.11 MAC standards, this provides QoS capabilities needed for real-time applications like IP telephony and voice A new standard for 2.4 GHz WLANs, this provides a bump in the data rate to 20+ Mbps (aiming at 54 Mbps), but backward-compatible products will not arrive soon Mired in technical debate and politics, this is critical to WLAN market expansion, but delays and indecisiveness may make it meaningless if de facto standards emerge Its goal is to define physical and MAC standards for fixed point-to-multipoint broadband wireless access (BWA) systems Security framework for all IEEE 802 networks, this is one of the key components of future multivendor interoperable wireless security systems, but implementation will not be simple
Standards – WWAN 2G/2.5G/3G
TDMA GSM CDMA GPRS EDGE CDMA 2000 1x CDMA 2000 1xEV CDMA 2000 3x WCDMA 2G standard used by AT&T wireless services 2G standard which is most widely used in Europe, based on TDMA 2G standard. It is the leading air interface in North America, patented by Qualcomm 2.5G standard for WWANs based on GSM systems deployed throughout Europe and in other parts of the world. GPRS is an IP-based, packet data system providing theoretical peak data rates of up to 160 Kbps Pushes the GPRS data rate to 384 Kbps, but upgrades may be costly for carriers 2.5 G standard for WWANs, this provides more efficient voice and packet switched data services with peak data rate of 153 Kbps Qualcomm is pushing 1xEV as an evolution of 1x technology. It uses a 1.25 MHz CDMA radio channel dedicated to and optimized for packet data, and has throughputs of more than 2 Mbps 3G standard for WWANs, this uses the same architecture as 1x. It offers 384 Kbps outdoors and 2 Mbps indoors, but operators will likely need to wait for new spectrum 3G standard similar to CDMA 2000 but uses wider 5 MHz radio channels. It provides data rates up to 2 Mbps, but more spectrum needs to be allocated in some areas
Technologies - WLANs
Wireless PHYs
Spread Spectrum (SS): a wideband radio frequency (RF) technique that trades off bandwidth efficiency for reliability, integrity, and security
Infrared (IR) technology: use very high frequencies just below visible light to carry data. IR cannot penetrate opaque objects. Inexpensive. Limited range.
CSMA/CA
Designed to solve hidden node situation in wireless communication to prevent packet collision
Technologies – WPANs
Bluetooth
A low-cost, low-power, short-range radio link for mobile devices and WAN/LAN APs. It offers fast and reliable digital transmission of both voice and data over the globally available 2.4 GHz ISM band
The raw throughput is 1 Mbps , and the actual data rate is 728 Kbps
Technologies - WWANs
Up to now, WWAN architectures have focused on voice services or at most low speed circuit-mode data. The plans for the future are to add higher-speed data services. Hotspot networks continue to be best served by WLANs and WPANs for the next two to three years rather than WWANs
Major cellular architectures include TDMA, cdmaOne, GSM/GPRS.
CDMA2000 and W-CDMA have limited support for data services
Wireless Internet – From a Business Perspective PC, Mac, Web station Internet Kiosk In-flight & Car Entertainment
enterprise
WAP, i-Mode, PDA TabletPC
Business Users Must Haves
To be able to Send/Receive and Store messages seamlessly from any device.
Access all available electronic data related to their work from most devices .
Central Network Based Address Book iTV
Access and Schedule Business and Personal related Appointments, Events, Reminders…
What does the enterprise need ?
Collaborative Wireless Applications that Increase Personal Productivity and which are:
Secure and Reliable
Easy to Deploy & Maintain
Modular to Allow for changes in size and technology
Anywhere, Anyhow, Anytime Access
Low TCO and Affordable Access
Operators Network Environment
Telco xSP PC TabletPC Internet Appliances PDA PC
Broadband
PC TabletPC Internet
Broadband
Laptop PC Phone
CDMA / GPRS WiFi hotspots LAN
PC PC
WiFI
Interactive TV Game console
WiFI Bluetooth
Phone PDA Laptop
What are the Opportunities for Carriers ?
Offer Collaborative Wireless Internet Solutions to the Enterprise market thus allowing them to :
Increase ARPU
Whether billed directly or via cross billing, business users will be forced to connect to your services, thus increasing your revenues.
Increase Customer Loyalty
As data becomes centric, the companies will be less apt to change the storage location
Operators can target individual business users by being taking a “complete provider approach” especially for address book and calendar and file storage.
Operator Business Models
Packaging Models, subscription based
Internet Access bundle
One broadband connection
One WiFi WLAN router
Collaborative Messaging Applications
Address book
Calendar
File storage
Optional Interface Customizations to Large Enterprises
Operator Business Models
Pay-per-use Models
Internet Access
WiFi hotspot prepaid hours
GPRS connections with billed upon kb transfer in/out
Voice access on per minute usage
Messaging Applications
Email, address book, calendar, file storage applications are available
SMS/MMS bundle
Digital Subscriber Line Technologies (DSL)
Definition of Terms Used
DSL stands for Digital Subscriber Line
High Speed Data
Subscriber Line
Upstream & Downstream
Symmetric and Asymmetric
No Dial Ups necessary
Exchange downstream upstream User
Types of DSL Technologies
Asymmetric DSL (ADSL)
ADSL Light
Rate-Adaptive DSL (RADSL) ADSL 2 ADSL 2+
High bit rate DSL (HDSL)
Symmetric DSL (SDSL)
Single-pair high speed DSL (SHDSL/HDSL2)
Very High Data Rate DSL (VDSL) Other DSL Technologies: IDSL & VoDSL
ADSL
Fast Broadband connection
Always On
Asymmetric
Dedicated Channel
Typical Data Rates in Australia today are :
1.5 Mbits/s downstream & 512 kbits/s upstream
Typical Reach: up to 3 km
Coexists with POTS (Plain Old Telephone Service)
ITU-T Recommendation G992.1
Equipment Used in ADSL
Transmission Line DSLAM (ATU-C)
DSL Modem (ATU-R) Splitter
Exchange Splitter Twisted Pair Customer Premises Splitter DSL Modem DSLAM Telephone PSTN PSTN Computer
ADSL Limitations
Frequency Response
Crosstalk
Other Limitation to ADSL Services are:
Bridge Taps
Loading Coils
Cable Joints
RIMS
Pair Gain
ADSL Line Coding & Modulation
What is line Coding
Line coding techniques used with ADSL:
DMT:
(DMT) Discreet Multitone Modulation
The transmission of several narrow sub-channels.
Divides signals into 247 separate channels at 4 kHz.
QAM/CAP: (QAM) Quadrature Amplitude and Phase Modulation
Combines two different types of modulation;
amplitude
and
phase .
(CAP) Carrierless Amplitude and Phase Modulation.
Similar to QAM, divides signals into three distinct bands.
ADSL Frequency Graph
ADSL Applications
Internet based applications
Online Shopping
Streaming Video
MP3 (music files)
E-commerce
Fast file transfer
Video on Demand
Other forms of ADSL
ADSL Light
Also known as G.Light and Universal ADSL
Splitterless
Lower Outlay Costs
Lower Data Rates
ITU-T Recommendation G.992.2
Exchange Splitter Twisted Pair Customer Premises Splitter DSL Modem DSLAM Telephone PSTN Computer
Other forms of ADSL cont…
Rate Adaptive DSL
Essentially the same as ADSL
Rate Adaptive Modem
Data rates similar to ADSL
Non-standard
Other forms of ADSL cont…
ADSL 2
Improves Data Rate and Reach
Enhanced capabilities
Power management
Seamless Rate Adaption (SRA)
ITU-T Recommendation G.992.3
ADSL 2+
Double the Downstream Bandwidth
HDSL
History & T1/E1
First DSL Technology Developed
Largely Installed
Symmetric Transmission
2 & 3 Pairs
Data Rates
Capable distance from exchange
Does not support POTS
ITU-T Recommendation G.991.1
also known as G.hdsl
Equipment Used in HDSL
E1 configuration
Digital Cross Connect (DCS)
Transmission Line
Customer Premises Equipment (CPE)
Mapping Interface
HDSL Transmission Unit (HTU)
DCS Exchange HTU - C HTU-R Customer CPE
Features of HDSL
Existing E1 needed line conditioning
No need of repeaters for HDSL
Greater Reach
Data Rates
HDSL Line Coding & Modulation
2B1Q (4-PAM): 2 binary 1 quaternary
Simple Modulation scheme
An amplitude and phase modulation scheme
Reduces the frequency spectrum by half
CAP
HDSL Applications
Designed for Business users
Symmetric nature - same upstream and downstream data rates
Examples of Applications
Video Conferencing & Distance Learning.
LAN/LAN interconnect
Web hosting
Other forms of HDSL
Symmetric Digital Subscriber Line (SDSL):
Symmetric One copper pair
Uses 2B1Q coding
Range of speeds
Phased out
Proprietary
SDSL Data Rate
128 kbit/s 256 kbit/s 384 kbit/s 768 kbit/s 1.024 Mbit/s
Maximum Distance (km)
6.71 6.56
4.42
3.97
3.51
Other forms of HDSL cont…
Single-pair high-speed DSL (SHDSL):
Known as G.shdsl with ITU –T and HDSL2 with ANSI
Single pair of wires
Distance ranges between 1.8 km to 6.5 km
Data Rates between 192 kbit/s to 2312 kbit/s (and growing)
Why SHDSL?
Does not coexist with POTS
VDSL
Very fast DSL resembling ADSL
Asymmetric and Symmetric
Faster Data Rates
Short distance from exchange
Provides for POTS and DSL
Uses Fibre in the loop network topology
ITU-T Recommendation G.993.1
VDSL Equipment
Transmission Line
VDSL Modem
Service Module
Splitter
Splitter Splitter VTU - R Service Module User ONU VTU-C (VTU-O) PSTN
VDSL Limitations & Line Coding
Limitations
Distance
Crosstalk & Interference
Line Coding
The same as ADSL
Two consortiums
Coalition QAM/CAP
Alliance - DMT
VDSL Data Rates & Distance
Symmetric/Asymmetric Loop Range (m)
Asymmetric 1000 Asymmetric 300
Downstream (Mbps)
26 52
Upstream (Mbps)
3 6 Symmetric Symmetric 1000 300 13 26 13 26
VDSL Frequency Graph
DS – Downstream US – Upstream Opt – Optional (either upstream or downstream) Voice Opt DS1 US1 DS2 US2 0
.004
0.025
0.138
~3 ~5 Frequency (MHz) ~8 12
VDSL Applications
Services that rely on fast data rates will benefit from VDSL
Fast Internet browsing
Video on demand
Remote Learning applications
Telehealth
High Quality Teleconferencing
Audio downloads
The only DSL service capable of the convergence of telephony, data and video
Current and Emerging DSL Technologies
IDSL (ISDN DSL)
Uses the data network and bypasses exchange switch Data rates are the same as ISDN: 144 kbit/s at a distance up to 5.5 km Benefits of IDSL:
Always on Flat rate rather than a per call rate
VoDSL (Voice over DSL)
Supports Voice and Data Supports multiple voice calls over single DSL circuit Dynamic Bandwidth All transmissions are digital
Comparison of xDSL Technologies
xDSL ADSL ADSL light HDSL SDSL SHDSL Modulation Method Symmetric or Asymmetric POTS Support
Yes 1
# of Twisted Pairs Maximum Reach (km)
5.5
Maximum Bitrate Downstrea m
6 Mbit/s QAM/CAP or DMT QAM/CAP or DMT 2B1Q Asymmetric Asymmetric Symmetric Yes No 1 1, 2, 3 5.5
3.6
1.5 Mbit/s 2 Mbit/s
Maximum Bitrate Upstream
640 kbit/s 512 kbit/s 2 Mbit/s 2B1Q PAM Symmetric Symmetric No No 1 1, 2 6.5
6.5
2.3 Mbit/s 2.3 Mbit/s 4 Mbit/s 4 Mbit/s
IDSL VDSL
2B1Q Symmetric QAM/CAP or DMT Asymmetric or Symmetric No Yes 1 1 5.5
1 144 kbit/s 52 Mbit/s 144 kbit/s 6 Mbit/s
Comparison of xDSL Technologies
ADSL ADSL light HDSL SDSL SHDSL IDSL VDSL 0 1 2 3 4 5
Distance from Exchange (km)
6 7
Fiber To The Home (FTTH)
What is FTTH?
CO/HE CO/HE // Old networks, optimized for voice CO/HE // Optical networks, optimized for voice, video and data
Note: network may be aerial or underground
// Copper Fiber 24 kbps - 1.5 Mbps 19 Mbps - 1 Gbps +
What is FTTH?
“An OAN in which the ONU is on or within the customer’s premise. Although the first installed capacity of a FTTH network varies, the upgrade capacity of a FTTH network exceeds all other transmission media.”
OAN: ONU: Optical Access Network Optical Network Unit
OLT: Optical Line Termination
OAN
CO/HE //
OLT Source: www.ftthcouncil.org
ONU
FTTH Components
Transport - ATM?
- Ethernet?
CO/HE
Philosophy - Retail - Wholesale Optical fiber and lasers
//
Technical considerations Architecture (Electronics) - PON?
- Active node?
- Hybrid?
Why FTTH?
Enormous information carrying capacity
Easily upgradeable
Ease of installation
Allows fully symmetric services
Reduced operations and maintenance costs
Benefits of optical fiber:
Very long distances
Strong, flexible, and reliable Allows small diameter and light weight cables Secure Immune to electromagnetic interference (EMI)
Why FTTH? - more capacity*
200 150 100 50 0 Twisted Pair Co-ax M ultimode Single-mode
* Typical system capability for 100 m link
Why FTTH? - longer distances*
100 90 80 70 60 50 40 30 20 10 0 Twisted Pair Co-axial M ultimode Single-mode
* Typical distance for 1 Gbps system capability
Why FTTH? - fiber versus copper
A single copper pair is capable of carrying 6 phone calls
A single fiber pair is capable of carrying over 2.5 million simultaneous phone calls (64 channels at 2.5 Gb/s)
A fiber optic cable with the same information carrying capacity (bandwidth) as a comparable copper cable is less than 1% of both the size and weight
Why FTTH? - fiber versus copper
//
Glass
Uses light Transparent Dielectric material nonconductive EMI immune Low thermal expansion Brittle, rigid material Chemically stable
Copper
Uses electricity Opaque Electrically conductive material Susceptible to EMI High thermal expansion Ductile material Subject to corrosion and galvanic reactions
How do optical fibers work?
Core
Carries the light signals
Silica and a dopant
Cladding
Keeps the light in the core
Pure Silica
Coating
Protects the glass
Acrylate (plastic)
How do optical fibers work?
Optical fibers work on the principle of total internal reflection CORE CLADDING
Light waves (“modes”) are reflected and guided down the length of an optical fiber
Types of lasers used
There are two laser technologies that are used for nearly all single mode communications applications
Fabry-Perot (F-P) lasers
Lower in cost, lower in power Poorer wavelength stability
Distributed Feedback (DFB) lasers
Higher cost, higher power
Excellent wavelength stability Excellent temperature stability
Internally modulated
Good for moderate powers and distances
Externally modulated
Ultimate today for quality in broadcast applications Vertical Cavity Surface Emitting Lasers (VCSELs)
Coming technology, promises lowest costs
Types of lasers used
Wavelengths used for Single Mode Fiber (long distances) communications
1310 nm
Usually lowest cost lasers
Used for shorter broadcast runs and short to moderate data runs
1550 nm
Can be amplified with relatively low-cost erbium doped fiber amplifiers (EDFAs)
Lasers are fabricated on a number of different wavelengths (about 1535 – 1600 nm) for wave division multiplexing (WDM) applications
Slightly lower fiber loss at 1550 nm
1490 nm
Increasingly popular for downstream data in 3
l
systems.
Cannot be amplified as easily Somewhat higher device cost
Single and Dual Fiber Systems
Single Fiber
Downstream broadcast* on 1550 nm
Upstream data on 1310 nm
Downstream data on either 1310 or 1490 nm* depending on system
Advantages
Less fiber deployed
Fewer optical passives (taps or splitters)
Fewer labor-intensive connections
* Downstream data can be carried at 1550 nm if not used for broadcast
Single and Dual Fiber Systems
Dual Fiber
Various plans, usually one fiber will be used for downstream and one for upstream, or one will be used for broadcast and one for data. Sometimes one will be used for specialized services, such as returning RF-modulated data from set top terminals
Advantages
Simplifies terminal passive components
Somewhat lower signal loss
Architectures
Passive Optical Networks (PONs)
Shares fiber optic strands for a portion of the networks distribution
Uses optical splitters to separate and aggregate the signal Power required only at the ends
Active Node
Subscribers have a dedicated fiber optic strand
Many use active (powered) nodes to manage signal distribution
Hybrid PONs
Literal combination of an Active and a PON architecture
Architectures – PON (A-. E- or G-)
OLT // // // Optical splitter 1x16 (1x2, 1x8) 1x32 (1x4, 1x8) Usually 10-20 km // // // ONU // //
Architectures – PON (2) (A-. E- or G-)
OLT 1550 nm broadcast (if used) 1490* nm data // // // // 1310 nm data // // ONU // //
* Data may be transmitted at 1550 nm if not used for video
Architectures – Active Node
OLT Up to 70 km // // // Processing (powered) Up to 10 km // // ONU // //
Architectures – Active Node (2)
OLT 1550 nm broadcast (if used) // // // // // Data, 1310 or 1550 nm (depending on distance) on separate fibers // // ONU
Architectures – Hybrid PON
OLT Up to 70 km Optical splitter // // // Processing (powered) // // Up to 10 km // // // // Optical splitter ONU
Architectures – Hybrid PON (2)
Single fiber, 1550 broadcast, 1310 bidirectional data OLT 1550 nm broadcast // // // // // // ONU Data, 1310 or 1550 nm (depending on distance) on separate fibers // // //
Technical considerations
Data
How much per home?
How well can you share the channel?
Security – how do you protect the subscriber’s data?
What kind of QoS parameters do you specify?
Compatible business services?
SLAs
T1
Support for voice?
Support for video?
Broadcast
IPTV
Technical considerations
Data
How much per home?
How well can you share the channel?
Security – how do you protect the subscriber’s data?
What kind of QoS parameters do you specify?
Technical considerations - Speed
Data requirements
Competition: ADSL, cable modem ~0.5 to ~1.5 Mb/s shared, asymmetrical
FTTH ~10 to 30 Mb/s non-shared or several 100 Mb/s shared, symmetrical
SDTV video takes 2-4 Mb/s today at IP level
HDTV takes maybe 5 times STDV requirement
Pictures can run 1 MB compressed
5.1 channel streaming audio would run ~380 kb/s
Technical considerations - Speed
Required Data Rate HDTV DSL or cable modem Streaming audio VoIP Picture in 15 seconds Service SDTV
Technical considerations – Speed
August 17, 2001: MGM, Paramount Pictures, Sony Pictures, Warner Brothers, and Universal Studios unveiled plans for a joint venture that would allow computer users to download rental copies of feature films over the Internet.
Estimated minimum time to acquire Braveheart Technology Modem 56 kb/s ISDN 128 Minutes Hours Days 2 20 kb/s December 9, 2002: “Hollywood's Latest Flop” Fortune Magazine
“The files are huge. At 952 Megabytes, Braveheart took just less than five hours to download using our DSL Line at home… in the same time we could have made 20 round trips to our neighborhood Blockbuster
DSL 1 Mb/s Cable 2.5 Mb/s FTTH 45 0.4
12 2.5
1
Technical considerations
Security
Data is shared in the downstream direction in most systems
Your Gateway filters out all packets not intended for you
But there is fear that someone will snoop on your data
FSAN has a low-complexity, low-security encryption scheme
802.3ah has formed a committee to study security
Manufacturers have taken their own tacks on security, from none to robust
Data Flow and Security - Downstream
Time division multiplex (TDM) – each subscriber’s data gets its turn.
T D H // // // // // T Box on side of home separates out only the data bound for that subscriber. But the fear is that someone will fool his box into giving data intended for another subscriber. Solution is to encrypt the data.
// H // Tom Harry D Dick
Data Flow and Security - Upstream
Time division multiple access (TDMA) – similar to downstream, with gap for laser start/stop T D H // // // // // Due to the physics of the network, Harry’s data flows upstream but does not come to Tom’s box, so Tom cannot see Harry’s data // H // Tom Harry Dick
Data Flow and QoS
If Dick has paid for more bandwidth, he gets more // // T D H // // // T // Tom If Tom’s packets need higher priority (e.g., telephone), they go first // H Harry D Dick
Telephony Considerations
Depending on whether the FTTH system is based on ATM or Ethernet, the basis of the phone technology is either conventional switched circuit or the newer VoIP
Conventional Switched-circuit Telephone
Bob . . .
During conversation, line is continually tied up in both directions
. . .
To other class 4 and 5 switches Concentrator (DLC) Switch Carol Alice Ted Donald
Switched Circuit Telephony
Example VoIP System
During conversation, line is shared with other data packets on each side of the router
Bob Customer Gateway Data Ted Customer Gateway Data To PSTN Softswitch Media Gateway Telephone packets Other data packets Carol Customer Gateway Router (switch) Data Alice Donald Customer Gateway Data Customer Gateway
One Form of Voice on Internet Protocol (VoIP)
Data
Video
Video is a popular service, which is a good basis for any new entrant FTTH provider.
There is one way to provide video on cable and satellite (broadcast) and one way to provide video on DSL (IPTV). There are two ways to provide video on FTTH (broadcast and IPTV).
The market place can sort out the use of each, to the benefit of the subscriber.
We will describe the differences.
Technical considerations - Video
Can send video several different ways on FTTH
Broadcast (cable TV standards)
Analog
Digital
Cable TV good engineering practice is 47-48 dB C/N
FTTH can achieve 48-51 dB C/N
Benefit from high volume and plethora of applications of cable boxes
RF return support for STTs IPTV – TV transmitted over Internet Protocol
Feasible, and some people are doing it in place of broadcast
Bandwidth hog, but statistics can work for you
Interesting hybrid model awaits hybrid STTs, but can give the best of both worlds
Ways of transmitting video
Ways of transmitting video – wave division muxing
Analog (Broadcast) optical transmitter Digital optical transceiver Always 1550 nm Wave division multiplexer (WDM) 1550 nm Optical network Analog optical receiver RF AGC Diplexer H Video to TVs L and STTs Wave division RF return from STTs multiplexer (WDM) A/D & proc Several wavelength plans: 1. 1310 nm bidirectional 2. 1490 nm downstream, 1310 nm upstream 1310 and possibly 1490 nm Digital optical transceiver Proc Voice (typ POTS) Data (typ 10/100Base-T), includes IPTV Headend, Central Office, OLT Home terminal, NID, Gateway, ONT
Ways of transmitting video – broadcast headend
Earth station IRD IRD Analog channels IRT Digital channels VOD server Analog RF m odulator, stereo, scram bler Analog RF m odulator, stereo, scram bler Transcoder, digital RF m odulator, upconverter Transcoder, digital RF m odulator, upconverter RF return signals Linear (broadcast, analog) optical transmitter To distribution plant Amplitude Spectrum diagram: Analog channels Digital channels
...
Frequency Ch 2 Ch 3
Ways of transmitting video – broadcast subscriber
Optics in Analog (broadcast, linear) optical receiver, one per endpoint Set top terminal Tuner Dem od Descram bing Select channel by selecting frequency (opt. RF Return) (Not required for analog-only service) Subscriber's TV
Ways of transmitting video – IPTV headend
IRD IRD Analog channels Encoder Encoder Digital (binary) optical transceiver (part of router) IRT IRT Digital channels Transcoder Transcoder VOD server Other data sources To groups of subscribers
. . .
H
Dow nstream data
D H D . . .
Ways of transmitting video – IPTV subscriber
Digital (binary) optical transceiver, one per endpoint Optics in FTTH interface Select data packets for subscriber In-hom e routing Other applications H
. . .
H D IP Set top terminal Packet request and selection Decoding Select "channel" by requesting to join a m ulticast group, or requesting a stream from a VOD server Subscriber's TV
Ways of transmitting video – IPTV unicast (VOD)
VOD server Router B Router A (headend) Router E In-hom e routing Program stream Program request Router C (netw ork) In-hom e routing Router D (NID) In-hom e routing In-hom e routing Set top term inal Subscriber's TV
Ways of transmitting video – IPTV unicast (VOD)
Encoder Transcoder Router B Router A (headend) Program packets Router C (netw ork) Router E In-hom e routing Larry's STT and TV 1 multicast video program Router D (NID) In-hom e routing Moe's STT and TV In-hom e routing In-hom e routing STT Curley's TV
Ways of transmitting video – IPTV multicast
Encoder Transcoder Router B Router A (headend) ?
Program packets Router C (netw ork) 1 video program Router E ?
Program requests ?
In-hom e routing ?
Router D (NID) In-hom e routing Larry's STT and TV In-hom e routing Moe's STT and TV In-hom e routing STT Curley's TV
Ways of transmitting video – IPTV multicast
Encoder Transcoder Router B Router A (headend) ?
Program packets Router C (netw ork) 1 video program Router E ?
Program requests ?
In-hom e routing ?
Router D (NID) In-hom e routing Larry's STT and TV In-hom e routing Moe's STT and TV In-hom e routing STT Curley's TV
END