Download IP Networks

IP NETWORKS – I & II
Internet Protocol Networks
CIS 585 Theoretical Presentation
28 Feb 2002
What This Paper/Topic Is About:
• Operation of internet and protocols.
• Internet architecture and multimedia.
• Nothing about infrastructure and web pages.
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Internet – The History
• Two nodes and Arpanet.
• 1969 – Kleinrock.
• First data sent, “login”.
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Internet Concepts and Protocols
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Protocols & Layering in IP.
Internet and internet.
Layers recurse or no strict layering.
Layers include,
- Physical, Link, Network,Transport
and Application layer.
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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.
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Internet Protocol Hierarchy
browser
Video
tool
RTP
Application
DNS
SNMP
SMTP
NNTP
ftp
http
Transport
UDP
TCP
IPv4, IPv6
PPP,SLIP
PPP
modem
ISDN
ICMP,IGMP
datalink
X.25
Token
ring
Ethernet
FDDI
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ATM
HIPPI
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Names, Addresses and Routes
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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
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Primary name server.
Secondary name server.
Division of zones.
Authoritative / master name server.
Temporary domain or pseudo domain.
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DNS Resolution
me
What is the IP of www.cnn.com?
I don’t know, this rootserver may know
LNS
Temple
me
What is the IP of www.cnn.com?
I don’t know, but com name server is
Root
server
me
What is the IP for www.ccn.com?
I don’t know, but cnn name server is…
Com
NS
me
What is the IP for www.cnn.com?
It is 132.151.1.35
CNN
NS
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Internet Addresses
• 32 bit long.
• For routing & identifying nodes.
IPv4
• 132.1.2.3
• 1080::::8:800:200C:417A
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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
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IP Address Class
thanks to henning schulzrine
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IP Addresses
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•
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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
10.25.1.5
10.25.1.6
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10.25.1.7
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IP Forwarding
router
packet
packet
packet
router
router
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
Version(4)
Header
length
Type of service
total length in bytes
. DTRC0
Flags
identification
time-to-live
0DFMF
protocol id
fragment offset (x8)
header checksum
source IP address
destination IP address
IP options
data
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IPv4 Packet Header
•
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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
Two forms of source routing:
• Loose source routing.
• Strict source routing.
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Hey, your route
should be :
155.247.166.60
18.181.0.31
Hey, your route
169.232.33.130
will be :
66.158.17.20
155.247.166.60
In between,
18.181.0.31
hop as u
169.232.33.130
wish!
66.158.17.20
155.247.71.60
Strictly ,
no other routes
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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
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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
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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
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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
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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
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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
N
- p
( 1 / Ri ).
i=1
• Variable delays.
• Application & coding added delays.
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Variable delays
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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
paths
Entire
day
Worst 6 hrs
Worst hour
All paths
1084
1.06%
1.44%
4.88%
Intra-US
U.S.-Europe
US-New Zealand
1060
1.04%
12
1.39%
10
2
2.58%
1.40%
1.52%
4.04%
1.51%
4.79%
5.71%
11.15%
6.97%
Source / Destination
Europe-N.Z.
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
Signaling:
• Media on demand.
RTSP
• Internet Telephony.
SIP
• Internet broadcast.
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
Media-Independent
QoS feedback
RTP
Mixers /
Translators
Loose session
Control
Encryption
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RTP Header Format
32 bytes
V
P X
CSRC
count
M
payload
type
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 !
BYE
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am I leaving?
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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
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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 - h:m:s:f:sf.
• Normal playtime - h:m:s: 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,PAUSE,TEAR
DOWN,REDIRECT.
• Difference with web caching.
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Session Description Protocol



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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
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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
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IP Networks by Henning Schulzrinne
Mbone by Hans Eriksson
IP Multicasting by Dave Kosiur
RFC 2974 (exptl)
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