IP NETWORKS I

1

• IP NETWORKS I II
• Internet Protocol Networks
• CIS 585 Theoretical Presentation
  28 Feb 2002

2
What This Paper/Topic Is About

• Operation of internet and protocols.
• Internet architecture and multimedia.
• Nothing about infrastructure and web pages.

3
Internet The History

• Two nodes and Arpanet.
• 1969 Kleinrock.
• First data sent, login.

4
Internet Concepts and Protocols

• Protocols Layering in IP.
• Internet and internet.
• Layers recurse or no strict layering.
• Layers include,
• - Physical, Link, Network,Transport
  and Application layer.

5
IP Layer definition

• Physical layer
• - point to point or point-to-multipoint
• - wires, optical fibers or free space
• - common link speed - 14.4 kb/s - 2.4 Gb/s
• - end-to-end delays
• - micro sec in LAN
• - milliseconds on multiple hop
  paths.

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IP Layer Definition

• Link Layer features include
• - point-to-point, multipoint service,
  broadcast
  or non-broadcast multiple access.
• - detect bit errors retransmit.
• Network Layer services include
• - carry packets across subnets (end-to-end),
• - packets use routers routing protocols .

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IP Layer Definition

• Transport Layer
• - operates only within end systems or hosts,
• - Built around TCP UDP.
• Additional protocol layers support
• - HTTP,SMTP,Telnet etc
• Nodes, Routers, Multi-homed hosts.

8
Internet Protocol Hierarchy
browser
Video tool
Application
RTP
DNS
SNMP
SMTP
NNTP
ftp
http
Transport
UDP
TCP
ICMP,IGMP
IPv4, IPv6
PPP,SLIP
PPP
datalink
modem
ISDN
X.25
Token ring
Ethernet
FDDI
ATM
HIPPI
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Names, Addresses and Routes

• Shoch naming convention.
• Network Object, addresses and routes.
• MAC/NIC address.
• IP address.
• Host name.
• Dial-ups Lease address.

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Internet Domain Name System

• By Paul Mockapetris in 1984.
• Name-to-address mapping.
• Distributed database.
• TLD CCTLD,
• Host.suborgn.orgn.tld.
• - www.cis.temple.edu
• - www.att.net and www.att.com

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Terms in Domain Name System

• Primary name server.
• Secondary name server.
• Division of zones.
• Authoritative / master name server.
• Temporary domain or pseudo domain.

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DNS Resolution
LNS Temple
me
What is the IP of www.cnn.com?
I dont know, this rootserver may know
Root server
me
What is the IP of www.cnn.com?
I dont know, but com name server is
Com NS
me
What is the IP for www.ccn.com?
I dont know, but cnn name server is
CNN NS
me
What is the IP for www.cnn.com?
It is 132.151.1.35
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Internet Addresses

• 32 bit long.
• For routing identifying nodes.
• 132.1.2.3
• 10808800200C417A

IPv4
IPv6
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IP Addresses

• 62.3 million hosts (Oct 1999) on net.
• Addresses assigned topologically.

Host part
Network part
132.65.22.1
15
IP Address Class thanks to
henning schulzrine
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IP Addresses

• Class A,B,C,D E type of addressing.
• Classless Interdomain routing.
• Architectural problems with IP.
• NAPT NAT.

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NAT NAPT
Internet
122.28.99.144
NAT Enabled Router
10.25.1.1
10.25.1.7
10.25.1.5
10.25.1.6
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IP Forwarding
router

packet
router
packet
packet
packet
packet
router
packet
node
node
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IP Service Model

• Simple network-layer service model.
• Datagram or connectionless delivery.
• Packets transmitted arrive,
• - Out of order,
• - On a best-effort basis,
• - Duplicated,
• - Fragmented.

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IPv4 Packet Format
Type of service
Header length
total length in bytes
. D T R C 0
Version(4)
Flags 0 D F M F
identification
fragment offset (x8)
time-to-live
protocol id
header checksum
source IP address
destination IP address
IP options
data
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IPv4 Packet Header

• Consist of packet header payload.
• Packets are fragmented.
• Fragmentation unreliable for audio/video.
• Header variables manipulated by router.

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Routing of Packets in IP
Hey, your route should be 155.247.166.60 18.1
81.0.31 169.232.33.130 66.158.17.20 In between,
hop as u wish!

• Two forms of source routing
• Loose source routing.
• Strict source routing.

Hey, your route will be 155.247.166.60 18.181
.0.31 169.232.33.130 66.158.17.20 155.247.71.60 St
rictly , no other routes
23
Transport Protocols in IP

• Commonly used TCP UDP
• Both support multiplexing
• UDP packet header

0
16 32
16-bit source port number
16-bit destination port number
16-bit UDP length(incl. header)
16-bit UDP checksum
data (if any)
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TCP With IP

• Is TCP or UDP the best for multimedia?
• TCP features flow control, reliability.
• End-to-end delay of TCP and multimedia.
• Congestion control of TCP and multimedia.

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UDP

• Used for streaming multimedia applications
• - Loss Tolerant.
• Other uses
• - with DNS
• - with SNMP

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IP Multicast

• Single IP packet to multiple receivers.
• Not connection oriented.
• Uses class D address format.
• Multicast can be achieved by,
• - Virtual circuit between sender receiver
• - Include all receiver addresses in the packet
• - Radio-like model.

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IP Multicast

• Sent packets only to subscribers.
• Use TTL and scoped multicast address.
• Discover subscribers using IGMP MLD
• Within an autonomous system use
• - MOSPF
• - DVMRP

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Multicast Inter Domain Routing

• Developing field.
• PIM dense mode and sparse mode.
• Core base tree protocol.
• Multicast is still an active research area.

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Multicast and Multimedia

• Reduces network bandwidth.
• Ex for a MPEG1 video stream of 1.5 mbps with 10
  receivers,
• Bandwidth needed at source (server) is
• For unicast 15 mbps
• For multicast 1.5 mbps

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Multicast - Today

• Desktops Server OS support multicast.
• Routers support some multicast protocols.
• Hubs Switches need no modification.
• Still, multicast is spotty.
• Mbone Multicast.

The Multicast backbone
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Internet Quality of Service

Principal Quality of Service Impairments
delay
packet loss
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End-to-End Delay

• Propagation delay.
• Transmission delay
• - p ( 1 / Ri ).
• Variable delays.
• Application coding added delays.

N
i1
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Variable delays

• Resource contention.
• Link-layer retransmissions.
• Queuing delay.
• Delay by Ethernet Ethernet switches.

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Application delay

• Look-ahead delay.
• Operating system delay.
• Coding delay.

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Packet induced delays

• Packet Loss
• - Packets that never arrive,
• - Packets that arrive late.
• Packet loss and continuous media applications.
• Packet Reordering.
• Packet Duplication.

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Internet Measurements

• Measurements of Internet Loss

Entire day
paths
Worst 6 hrs
Worst hour
Source / Destination
All paths
1.44
4.88
1084
1.06
Intra-US
1060
1.40
4.79
1.04
U.S.-Europe
12
1.52
5.71
1.39
US-New Zealand
10
4.04
11.15
2.58
Europe-N.Z.
2
1.51
6.97
0.58
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IP architecture for media
Media Transport protocols
QoS protocols
architecture
Signaling protocols
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IP architecture for media

• Quality of Service

Role of SNMP, RTCP
Resource Management
Differentiated services
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IP architecture for media
RTSP

• Signaling
• Media on demand.
• Internet Telephony.
• Internet broadcast.

SIP
SAP
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RTP for Multimedia Data

• Common requirements of media streams
• Sequencing.
• Intra-Media Synchronization.
• Inter-Media Synchronization.
• Payload Identification.
• Frame indication.

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RTP functionality
Multicast friendly
QoS feedback
RTP
Loose session Control
Media-Independent
Mixers / Translators
Encryption
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RTP Header Format
32 bytes
CSRC count
M
payload type
V
P
X
sequence number
timestamp
synchronization source identifier (SSRC)
contributing source identifiers(CSRC)
header extension
payload(audio,video)
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RTCP Control Management
RTCP Packet
Source descriptor
Sender reports
Receiver reports
Bye ! am I leaving?
BYE
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Real-Time Streaming Protocol

• RTSP Features
• Relationship with HTTP
• Timing
• Aggregate and Stream Control
• Caching

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Real-Time Streaming Protocol

• proposed standard for control of streams.

S1
S2
S3
Client
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Real-Time Streaming Protocol

• Can be used as a conference recorder.
• Syntax is similar to HTTP.
• Different from HTTP TCP REDIRECT.
• Notion of session.
• Extendable using OPTIONS request.

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RTSP Timing

• SMPTE time - hmsfsf.
• Normal playtime - hms fraction of sec.
• Absolute time

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RTSP Stream Control Caching

• Individual and Aggregate streams
• Example of a movie.
• Use of requests - DESCRIBE , SETUP,PLAY,RECORD,PAU
  SE,TEAR DOWN,REDIRECT.
• Difference with web caching.

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Session Description Protocol

• Text format for multimedia sessions.
• SDP is not really a protocol.
• Example linking a session to a web page.
• SDP can convey
• - type of media.
• - media transport protocol.

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Session Description Protocol

• SDP can convey
• - format of the media.
• - time and duration of the session.
• - security info related to as encryption.
• - session names and subject information.
• - human contact information related to a session.

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Session Initiation Protocol

• What is SIP ?
• Message Encoding
• Addressing and Naming
• Basic Operations and Telephony services
• Multiparty calls
• SDP SAP

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References for this presentation

• IP Networks by Henning Schulzrinne
• Mbone by Hans Eriksson
• IP Multicasting by Dave Kosiur
• RFC 2974 (exptl)