Download Perfect Storm – Wireless/VoIP Payam Maveddat AVP of

Multimedia Services in the
Internet
Dr. Dorgham Sisalem
[email protected]
These presentation materials describe Tekelec's present plans to develop and make available to its customers certain
products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a
written agreement signed by Tekelec and customer.
Goals
•
Overview of multimedia service
•
Understanding of multimedia services in the Internet
•
Understanding of the general pictures
 Transport protocols, signaling, traffic types, QoS
•
Practical experience with protocols and applications
•
Basic knowledge of the different involved protocols and concepts
•
We are not dealing with:






Audio and video compression
Web programming
Image processing or speach recognition
Audio and video hardware
MMS or video over GSM
Where to get the latest movies or how to copy a DVD
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Structure
•
Pre-requirements
 Good understanding of IP networking principles
•
2-Hour credit
•
Exam
 10-12 10.07.07
•
Office hours: After the lecture
•
Contact:
 [email protected]
•
Slides:
http://www.iptel.org/~dor/uni.htm
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References
•
www.ietf.org (RFCs and drafts)
•
www.iptel.org (SIP tutorial)
•
www.cs.columbia.edu/~hgs/internet XXXX
•
Stevens, „TCP/IP Illustarted, V1“ (basic protocols)
•
Ferguson, Huston, „Quality of Service“ (general QoS stuff)
•
Henry Sinnreich and Alan B. Johnston „Internet Communication Using SIP:
Delivering VoIP and Multimedia Services with Session Initiation Protocol“
•
Olivier Hersent, David Gurle, Jean-Pierre Petit,“IP Telephony“
•
Huitema, „IPv6“
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Acknowledgements
•
Slides based on work of Henning Schulzrinne, Jim Kurose, Michael
Smirnov, Georg Carle, Jiri Kuthan, Heikki Waris, Kevin Fall, Jim Chou,
Thinh Nguyen, Vishal Misra, Steve Deering, Geert Heijenk, Ofer
Hadar, John Floroiu, Nick McKeown, Eric D. Siegel, Ibrahim Matta,
Steven Low, Vincent Roca, Nitin H. Vaidya, Charles Lang as well
many other anonymous contributers.
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Topics: Introduction
• Introduction to Internet
 Very brief covering



Difference between IP and PSTN
Basic concepts
Transport protocols: TCP, UDP, RTP
 Why use UDP for VoIP and TCP for signaling?
 What is the difference between RTP and RTCP
 You are expected to have visited the networking lecture of Prof.
Wolisz
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Topics: VoIP
•
What is VoIP
•
Signaling
•
Addressing
•
Intelligent services
•
Deployment problems: NAT, emergency
•
Integration with PSTN
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Topics: VoIP
What happens
during this
registration?
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Topics: VoIP
What does this
address mean?
How do we find the
other side?
How do we call a
PSTN number?
What happens when
we press call?
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‘07 | 9
VoIP in UMTS
•
What does IMS stand for?
•
Basic concepts of UMTS
•
What is the difference to normal VoIP?
•
How does it work?
•
Why a special version?
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Problems of VoIP
•
Why doesn’t VoIP work over my DSL link
 What are the problems of network address tarnslators?
 How to deal with firewalls
•
Regulatory issues
 How can I call the 110?
•
Scalability
 How do I build a reliable carrier-grade VoIP infrastructure
•
Security
 What kind of attacks can we expect
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Group Communication
•
What is the difference between broadcast and multicast
•
How does a conference bridge work
•
What solution is best fro which scenario?
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‘07 | 12
Peer-To-Peer Networking
•
How do P-2-P solutions work?
•
What solutions exist?
•
What is Skype?
•
Basic concepts and approaches
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Instant Messaging and Presence
•
What is presence and IM
•
Basic concepts and approaches
•
What solutions and technologies exist
•
What are the current standards
•
Relation to VoIP
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‘07 | 14
Streaming
•
How are resources described?
•
What happens when we press play? (signaling)
•
What does it mean when it says “buffering” or ran out of buffer
•
What protocols exist and how do they work?
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Public Switched
Transmission Network
PSTN
These presentation materials describe Tekelec's present plans to develop and make available to its customers certain
products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a
written agreement signed by Tekelec and customer.
Public Switched Transport Network
(PSTN)
•
Exists now for around 100 years
•
800 M Subscribers
•
Optimized for Voice and Data (Fax) services
•
Guaranteed bandwidth share
•
In one country only a few exist

usually a big one controlling the whole network
•
Cost of switching equipment high (A few millions for a carrier grade switching
component
•
Signaling to session establishment and control based on SS7
•
Hierarchical address structure (E.164)
International
Identity
2 digits
National
Identity
2-to-5
digits
User
Identity
11 to 5
digits
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Subaddress
Up to 40 digits
‘07 | 17
PSTN Architecture in Germany
Fernnetz
AVSt
Auslandvermittlungsstelle
Ca. 50 HVSt
Hauptvermittlungsstelle
Ca. 550 KVSt
Knotenvermittlungsstelle
Ortsnetz
Ca. 500 OVSt
Ortvermittlungsstelle
Ca. 40 M Teilnehmer
Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida
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Routing in PSTN
Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida
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Switching in PSTN
Capacity 100
99 calls active
busy
Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida
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Resource Sharing (TDM)
•
Time division multiplexing (TDM)
 Allocate a time slot to a each call

Resources are guaranteed
 May under utilize channel with idle senders
 Applicable only for a fixed number of flows
 Requires precise timers
10 kb/s
10 kb/s
10 kb/s
1 link, 30kb/s speed
Multiplexer
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Intelligent Service in PSTN
Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida
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Intelligent Service in PSTN
•
Service switching point (SSP): A switch enhanced with logic for identifying IN
services
•
Service Transfer Point (STP): Interface of the switch to the IN environment
•
Service Control Point (SCP): Control the execution of the service
•
Service Management System (SMS): Control and manage the available services
and provide the interface for adding new ones
•
Intelligent Peripheral: Additional components for providing certain services such as
announcements
•
Feature Node: Execute services provided by private entities (similar to SCP)
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Example of Free Call
•
Allow calls to a generic number: No costs for the caller, final location decided based on time
of day ….
Ref. Prof. Dr.-Ing. Habil. Lutz Winkler, FH Mittweida
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Introduction to the Internet
These presentation materials describe Tekelec's present plans to develop and make available to its customers certain
products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a
written agreement signed by Tekelec and customer.
General Words
•
Since more than 20 Years with the same technology (TCP/IP)
•
Moved from 4 sites in 1968 to around 200 M hosts today
•
Flat addressing and routing architecture
•
Based on packet switching
•
(the) Internet: “collection of networks and routers that spans x countries and
uses the TCP/IP protocols to form a single, cooperative virtual network”. (Comer)
•
intranet: connection of different LANs within an organization
 Private
 may use leased lines
 usually small, but possibly hundreds of routers
 may be connected to the Internet (or not), often by firewall
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Packet Switched Communication
End Users
End Users
Router
Data Packets (Voice, Video, Games, Signaling…)
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What‘s a network?
•
Host: Communication end point (PC, PDA, cell phone, coffee machine ...)
•
Link: carry bits from one place to another (or maybe to many other places)
•
Switch/gateway/router: move bits between links, forming internetwork
 IP router receives a packet from one interface and sends it out over another
1
2
1
2
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What‘s a Protocol?
• Protocol: rules by which active network elements communicate
with each other
•
protocols = “algorithms + data structures”




•
formats of messages exchanged
actions taken on receipt of messages
how to handle errors
hardware/operating-system independent
real-life examples:
 rules for meetings
 conversational rules (interrupts, request for retransmission, ...)
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Protocol Mechanisms (What Do Protocols Do
for a Living?)
• All or some of the following:
 addressing/naming: manage identifiers
 fragmentation: divide large message into smaller chunks to fit lower
layer
 resequencing: reorder out-of-sequence messages
 error control: detection and correction of errors and losses

retransmission; forward error correction
 flow control: avoid flooding/overwhelming of slower receiver
 congestion control: avoid flooding of slower network nodes/links
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Architectural Requirements of the Internet
•
Generality
 Support ANY set of diverse applications,
•
Heterogeneity
 Interconnect ANY set of network technologies
•
Robustness
 More important than efficiency
•
Extensibility
 More important than efficiency
•
Scalability
 (A later discovery. How many ARPAnets could the world support? A few
hundred, maybe… ?)
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End-to-End Principle
Foundation of the Internet architecture:
•
Dumb network, smart end systems
 (Exact opposite of telephone network!)
•
Dumb networks: require only least common service
 Datagram service: no connection state in routers
 Best effort: all packets treated equally.
 Can lose, duplicate, reorder packets.
•
Smart hosts:
 Maintain state to enhance service for applications.
 New applications can be introduced at end systems with no need for network
upgrades.
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Resource Sharing (Statistical)
•
Statistical multiplexing
 Traffic is sent on demand, so channel is fully utilized if there is traffic to
send
 Any number of flows
5 kb/s
20 kb/s
5 kb/s
1 link, 30kb/s speed
Multiplexer
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‘07 | 33
Resource Sharing (Statistical)
•
Statistical multiplexing
 Resources are NOT guaranteed
 Need Mechanisms to prevent congestion and domination
5 kb/s
50 kb/s
5 kb/s
Multiplexer
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1 links, 30kb/s speed,
50% Loss
‘07 | 34
Who runs the Internet?
• “nobody”
• standards: Internet Engineering Task Force (later. . . )
• names: Internic (US), RIPE (Europe), . . .
• numbers: IANA (Internet Assigned Numbers Authority)
• network: ISPs (Internet Service Providers), NAPs (Network
Access Points), DFN, . . .
• fibres: telephone companies (mostly)
• content: thousands of companies, universities, individuals, . . .
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How big is the Internet?
• Many measures:






networks (routed entities)
domains, host names (but: several names per host!)
directly (continuously) attached hosts (“ping’able”)
IP-connected hosts (SLIP, PPP)
firewalled hosts
e-mail reachable
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Host Count
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What Networks are There?
•
Access (ISP):
 Carry data from users
•
Core
 Carry data from access
•
Network peering points
 Connect networks together
•
Some enterprises might be connected directly to core networks
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An Example Network
USER
Backbone
Local Loop Carrier
Point of Presence
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Network Access Point: Chicago NAP
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Making the Standards
•
Internet Architecture Board: IAB
 architectural oversight
 elected by ISOC
•
Internet Engineering Steering Group (IESG)
 approves standards
•
Internet Society: ISOC
 Conferences
 “hosts” IANA
•
Internet Assigned Number Authority: IANA
 keeps track of numbers
 delegates Internet address assignment
•
Internet Engineering Task Force: IETF
 Define the problems and specify solutions to them
 Run by interested people (people should contribute in person and not as company
representatives)
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RFCs and Drafts
•
“Request for Comments”, since 1969
•
most RFCs are not standards!
•
Internet drafts: working documents, but often used for prototypes
•
edited, but not refereed
•
numbered sequentially (Spetember 2002: more than 3600)
•
check the April 1 ones. . . (RFC 1149)
•
ftp://ds.internic.net/rfc
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‘07 | 42
TCP/IP Stack
TCP/IP
Application
Application
VoIP
Email ..
Transport
Transport
TCP, UDP,
SCTP
Network
Network
Link
Link
Link
Router
Host
Host
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Network IP, IPv6
Ethernet
Cable,
UMTS
‘07 | 43
Internet Protocol
•
Deliver an IP packet from host to host(s)
•
Connectionless, unreliable
 No loss handling
 No flow or congestion control
VoIP
SMTP
ICMP
HTTP
FTP
RTP
DNS
UDP
TCP
IPv4/IPv6
PPP
Ethernet
GPRS
SONET
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AALx
V.x
ATM
‘07 | 44
Internet Names
•
Physical link address
 Ethernet, ATM ...
 Flat
•
IP address
 Identify an interface
 Topological
•
IP Name
 Identify the object to reach
 Hierarchical
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IP Addresses
• Identify an interface not host:
 A host can have more than 1 address
• IP addresses are 32-bit numbers (4.3 billion of them!)
• Divided into parts: (network prefix, host number)
• 4 decimal numbers, called “dotted quad”
• Each (decimal) number is one byte
 Example: 128.32.25.12
• Can generally be used in place of names
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Internet Packets
•
A lot of headers describing the different layers
Phy
IP
UDP/
TCP
Body
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IP Header
•
Version: 4 or 6
•
Header length: number of 32 bit words of header
•
Type of Service: delay, throughput, reliability, monetary
•
Total length: length of packet in bytes
•
Identification: identify packet
•
Flag:



MBZ:
Do not fragment
More fragments
•
Fragmentation offset: Distance from the first bit of the original packet
•
Time-to-Live: Avoid loops
•
Protocol: Which protocol is used (TCP, UDP, ICMP ..)
•
Header Checksum: Calculated over IP header
•
Source address: Address of sender
•
Destination address: Address of receiver
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Special Addresses
•
Private addresses: Only of meaning inside an intranet
 172.16 through 172.31 16
 192.168.0 through 192.168.255 256
•
Loopback: 127.0.0.1 (local interface)
•
Local broadcast: all 1 (receive by all members of link)
•
Multicast:
 224.0.0.0
239.255.255.255
 Do not describe a host or interface but a group of receivers
•
Reserved: 240.0.0.0
255.255.255.255
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IPv6: Why move to another protocol?
•
Lack of IP addresses
 Support for nearly endless range of addresses
•
Explosion of routing tables
 Allow for better aggregation and routing hierarchies
•
Better handling of options
 Reduce complexity of IP header
•
Better support for management and administration
 auto configuration and renumbering
 Support plug&play
•
Need for better support for mobile and secure communication
 Remove the need for network address translators
 Really?
•
Better support for QoS (which is not correct)
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IPv4 vs. IPv6 Header
•
8 fields, fixed 40 octet size
•
14 fields, at least 20 octets
•
128 bit addresses
•
32 bit addresses
•
fragmentation only in endpoints, or lower layer
•
fragmented packet processing at every hop
•
header checksum recalculation at every hop
•
variable Options field for extra processing information

•
Usage of Path MTU discovery
no checksums

Already in lower layers
•
new 20 bit flow label field
•
options in Extension Headers
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IP Names
host name (has IP address)
organization administering
host
Organization administering
subnames to left
organization type or country
Oxany.fokus.fhg.de
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Getting From A to B
These presentation materials describe Tekelec's present plans to develop and make available to its customers certain
products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a
written agreement signed by Tekelec and customer.
Getting from A to B
•
Know name: need to know IP address
 Domain Name System (DNS)
•
Know IP address: need to know the way
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Getting From A to B
Name to IP Address
These presentation materials describe Tekelec's present plans to develop and make available to its customers certain
products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a
written agreement signed by Tekelec and customer.
Domain Name System
•
The Domain Name System (DNS) is a distributed database that is
used by TCP/IP applications to…
 map between hostnames and IP addresses,
 and to provide application routing information.
•
Distributed database:
 No single site on the Internet “knows it all.”
 Each site maintains its own database and runs a server that other
systems on the Internet can query.
•
DNS is the client/server protocol.
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Domains
•
Top level domains
 arpa domain

Special domain for address-to-name mappings
 generic (organizational) domains

3-character domains (e.g. edu, com, org, …)
 Country (geographical) domains

2-character domains

Found in ISO 3166

Some countries form second-level domains
 e.g.: .ac.uk is for academic institutions in the United Kingdom.
 New generic top level domains (gTLD)

•
.biz, .tv, .name, .aero ...
Note: No single entity manages every node.
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DNS hierarchical name space
unnamed root
top level domains
de
arpa
us
Maintained by DeNIC
com
edu
gov
wsu
eecs
gazoo
math
int
mil
net
org
•Node labels up to 63 characters.
•Root node has null label.
•Comparisons are case insensitive.
•Domain name formed as follows:
•start at node and work toward root
•use a “dot” to separate labels
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Resolvers and Name Servers
•
Applications (clients and servers) contact a DNS server by calling
functions in a library known as a resolver.
 The resolver is accessed through the functions gethostbyname() and
gethostbyaddr().
 The resolver code is in a system library and is linked into the application.
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DNS Operation
•
What does a server do when it does not have the requested
information?
 Every name server must know how to contact the root name servers (via
IP address).
 Name server contacts a root server
 Root servers know the name and IP address of all the second-level
domains
 Each names server caches information from recent queries.
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Practical
•
nslookup
•
http://www.internic.org
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Routing Packets from
A to B
These presentation materials describe Tekelec's present plans to develop and make available to its customers certain
products, features and functionality. Tekelec is only obligated to provide those deliverables specifically included in a
written agreement signed by Tekelec and customer.
Hierarchical PSTN Routing
030
040
050
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060
‘07 | 63
Distributed IP Routing
193.175.135.21
Core
Access
PictureTel
Enterprise
Core
195.37.78.225
Access
Access
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IP Routing
• How to get from A to B?
 Different paths are possible!!
 Neither A nor B know the best path in advance!!
• Goal: set routing tables for packet forwarding in hosts and
routers, typically based on some optimality criterion.
• Questions:





who determines entries?
based on what information (hops, delay, cost, ...) ?
how often does it change (hop vs. delay)?
where is routing information stored?
algorithm used to compute routes?
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Tekelec Confidential
Non-Binding
‘07 | 65
IP Routing: Goals
•
scalability
•
“safe” interconnection of different organizations
•
adopt quickly to changes in topology
•
avoid routing loops or at least terminate them quickly
•
self-healing, robust
•
Distributed: No central component to determine the path
•
efficient: can’t use 90% of bandwidth for routing info
•
multiple metrics (QOS, price, politics, ...) not yet
•
routes should be (near) “optimal”
•
can’t have all hosts/networks in single table hierarchical
Tekelec Confidential /
For Discussion Purposes Only /
Tekelec Confidential
Non-Binding
‘07 | 66
IP Routing
•
Every router needs to determine the next hop to which to send the data
•
Routing database: one entry for every possible destination in the system:






Destination address: the IP address of the host or network;
Next hop: the first router along the route to the destination;
Interface: the physical network which must be used to reach the first hop
Metric: a number, indicating the distance to the destination;
Timer: the amount of time since the entry was last updated;
Flags and other internal information.
1
2
1
2
Tekelec Confidential /
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Tekelec Confidential
Non-Binding
‘07 | 67
IP Routing
•
DB initialization: description of the entities that are directly connected;
•
DB update: messages from neighboring gateways.
•
Decision taken based on topology and updated continously
 No gurantee that two packets will follow the same path
•
ifconfig (ipconfig)
•
Netstat
•
http://www.traceroute.org/
Tekelec Confidential /
For Discussion Purposes Only /
Tekelec Confidential
Non-Binding
‘07 | 68
Intra-Domain Routing
•
Set the routes inside an
autonomous system (AS)
 AS: a a collection of routers
and system administered by
one entity
 Has a AS number assigned by
IANA
•
Different ASs might use
different intra-domain routing
schemes
•
Changes in one AS do not
effect other domains
•
AS connects to another AS
through one or more border
routers
Core
Access
Enterprise
Core
Access
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For Discussion Purposes Only /
Tekelec Confidential
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Access
‘07 | 69
Contact Information
Dr. Dorgham Sisalem
Director, Strategic Architecture
Tekelec Network Signaling Group
Tel.:+49 30 32 51 32 14
E-mail: [email protected]
Tekelec Confidential /
For Discussion Purposes Only /
Tekelec Confidential
Non-Binding
‘07 | 70