organizing the internet l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Organizing the Internet PowerPoint Presentation
Download Presentation
Organizing the Internet

Loading in 2 Seconds...

play fullscreen
1 / 67

Organizing the Internet - PowerPoint PPT Presentation


  • 145 Views
  • Uploaded on

Organizing the Internet. Chapter 9. Knowledge Checkpoints. Internet protocols Routing and protocols Internet addressing Organization of the Internet How ISPs work. Terms to Remember. TCP/IP suite Packet sequence numbers Port numbers UDP, ICMP,IGMP ARP, RARP RIP, OSPF, IGP, EGP, BGP

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Organizing the Internet' - niveditha


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
knowledge checkpoints
Knowledge Checkpoints
  • Internet protocols
  • Routing and protocols
  • Internet addressing
  • Organization of the Internet
  • How ISPs work
terms to remember
Terms to Remember
  • TCP/IP suite
  • Packet sequence numbers
  • Port numbers
  • UDP, ICMP,IGMP
  • ARP, RARP
  • RIP, OSPF, IGP, EGP, BGP
  • ARIN, RIPE,APNIC,ICANN
  • CIDR
  • NSP
  • ASP
tcp ip
TCP/IP
  • Transmission Control Protocol / Internet Protocol
  • Oldest networking standard (DoD, 1974)
  • Most popular network protocol (70%)
  • Small packet size
  • TCP/IP allows reasonable efficient and error-free transmission
  • Combination of two protocols
    • TCP - Transmission Control Protocol
    • IP - Internet Protocol
internet protocols
Internet Protocols
  • TCP/IP (suite)
    • Provides layer 4 functionality
    • TCP divides data into packets with a sequence number
    • Assigned to a port (range 1-65,535)
    • Ports identify applications on servers
    • Ports identified by incoming and outgoing
    • IP handles packet forwarding and transport of datagrams across a network
    • Defines the basic unit of data
    • Functions at Layer 3
    • Provides host addressing, error notification, fragmentation, reassembly, routing, and packet time-out
internet protocols6
Internet Protocols
  • UDP
    • Layer 4
    • Operates over IP
    • End-to-end connectionless, unreliable datagram service
    • Used for query based applications, multicasting and VoIP
  • ICMP
    • Provides error-handling
    • Messages related to network management
  • IGMP
    • Layer 3
    • Allows Internet hosts to participate in multi-casting
tcp ip7
TCP/IP
  • TCP performs the packetizing function
    • Breaking data into smaller packets
    • Numbering packets
    • Ensuring reliable delivery of packets
    • Ordering packets at the destination
tcp ip8
TCP/IP
  • IP performs network routing and addressing functions
    • IPv4 - 32-bit address - 192-bit header
    • IPv6 - 128-bit address - 320-bit header
requirements for tcp ip
Requirements for TCP/IP
  • This information should either come from an internal configuration file or a bootp or DHCP server
    • IP address
    • Subnet mask
    • IP address of DNS server
    • IP address of router, gateway or switch
tcp packet
TCP Packet

1

2

3

4

5

6

7

8

9

10

11

User Data

1 Source port number 16 bits

2 Destination port number 16 bits

3 Sequence number 32 bits

4 ACK number 32 bits

5 Header length 4 bits

6 Unused 6 bits

7 Flags 6 bits

8 Flow control 16 bits

9 CRC 16 16 bits

10 Urgent pointer 16 bits

11 Options 16 bits

network and transport layers
Network and Transport Layers
  • The transport & network layers sit between the application layer and the data link layer
  • They accept messages from the application layer, format, and address them for transmission by the data link layer
  • Both the sender and receiver have to agree on the rules or protocols that govern how their network layers will communicate with each other.
transport protocol
Transport Protocol

A transport protocol is responsible for:

  • End-to-end delivery of the message
  • Breaking large messages into packets for transmission and reassembling them at the receiver’s end (packetizing)
  • Determining the correct network layer and data link layer addresses (addressing)
network protocol
Network Protocol

A network protocol is responsible for:

  • Determining where the message should be send next on its way to its final destination (routing)
    • Selecting the best path from computer to computer through the network
  • Can share the addressing function with the transport layer
protocols
Protocols
  • There are many transport and network protocols
  • They all perform the same or similar functions
  • They are incompatible with each other
  • Vendors now provide software with multiprotocol stacks
protocols15
Protocols

The four most commonly used protocols are:

  • TCP/IP
  • IPX/SPX
  • X.25
  • SNA
ip packet version 4 vs 6
IP Packet version 4 vs 6

IP4

1

2

3

4

5

6

7

8

9

10

11

12

13

14

1 Version number 4 bits

2 Header length 4 bits

3 Type of Service 8 bits

4 Total length 16 bits

5 Identifiers 16 bits

6 Flags 3 bits

7 Packet offset 13 bits

8 Hop limit 8 bits

9 Protocol 8 bits

10 CRC 16 16 bits

11 Source address 32 bits

12 Destination Address 32 bits

13 Options varies

14 User data varies

15 Priority 4 bits

16 Flow name 8 bits

17 Next header

IP6

1

15

16

4

17

8

11 (128 bits)

12 (128 bits)

14

ipx spx
IPX/SPX
  • Internetwork Packet Exchange / Sequenced Packet Exchange
  • Based on a routing protocol developed by XeroX (mid 70’s)
  • Primary network protocol used by Novell up until they released version 5 of Netware
ipx spx18
IPX/SPX
  • A combination of two protocols
    • SPX - Sequenced Packet Exchange
      • Breaking the data into smaller packets
      • Numbering them
      • Ensuring each packet is reliably delivered
      • Putting them in proper order at the destination
    • IPX - internetwork packet exchange
      • Routing
      • Addressing
  • Similar to TCP/IP
ipx packet

1

2

3

4

5

6

7

8

9

10

IPX Packet

User Data

1 Checksum 2 bytes

2 Length 2 byte

3 Control 1 byte

4 Type 1 byte

5 Destination address 6 bytes

6 Destination network address 4 bytes

7 Destination socket 2 bytes

8 Source address 6 bytes

9 Source network address 4 bytes

10 Source socket 2 bytes

IPX packet

spx packet

1

2

3

4

5

6

7

SPX Packet

User Data

SPX packet

1 Control 1 byte

2 Type 1 byte

3 Source ID 2 bytes

4 Destination ID 2 bytes

5 Sequence number 2 bytes

6 ACK number 2 bytes

7 Allocation number 2 bytes

slide21
SNA
  • Systems network architecture
  • Developed by IBM in 1974, IBM proprietary non-industry standard protocol
  • Transmission control layer performs packetizing
  • Path control layer performs routing and addressing
  • Requires special equipment to translate between lans and mainframes
  • Advanced peer-to-peer networking (APPN) was developed by IBM to support TCP/IP
  • Uses SDLC as its data link layer protocol
sna 7 layer model
SNA - 7 Layer Model

Application Layer

Presentation Layer

Data Flow Layer

Transmission Control

Path Control

Data Link Control

Physical Layer

transport and network protocols summary
Transport and Network Protocols - Summary

Routing and

Addressing

Packetizing

TCP

IP

TCP/IP

SPX

IPX

IPX/SPX

X.25

X.3

PLP

Transmission

Control Layer

SNA

Path Control Layer

transport layer functions
Transport Layer Functions
  • Linking to the application layer
  • Packetizing
  • Connection-oriented routing
  • Connectionless routing
  • Quality of service (qos)
linking to the application layer
Linking to the Application Layer
  • Each type of application has a unique port address
  • Application software sends both source and destination port addresses to the transport layer
  • Standard port addresses
    • Port 80 - web server
    • Port 21 - FTP
    • Port 23 - telnet
    • Port 25 - SMTP
packetizing
Packetizing
  • Breaking large data messages into smaller packets for transmission through the network
  • Size is dependent of data link layer protocol
    • Default size without protocol is 536 bits
    • Size can be negotiated between sender and receiver
  • Numbering packets (sequencing) when needed
  • Ensuring reliable delivery of every packet
    • Delivered one at a time or held until all have arrived at the destination
  • Reassembling and ordering packets at the destination
connection oriented routing
Connection-Oriented Routing
  • Sets up a virtual circuit between sender and receiver
    • Transport layer sends a special packet called a SYN
  • Virtual circuit appears to the application software to use point-to-point circuit-switching
    • Actually uses store-and-forward switching
  • Network layer decides which route the packets will be travelling and sends them sequentially
  • High overhead - open/close of circuit
connectionless routing
Connectionless Routing
  • Each packet of a large transmission is treated separately and makes its own way through the network
  • Packets may travel different routes and at different speeds through the network
  • Sequence number must be added to each packet by the Network layer
  • Network layer at receivers side must reassemble packet in sequence
connectionless vs connection oriented routing
Connectionless vs. Connection-Oriented Routing
  • TCP/IP can operate as connection-oriented or connectionless.
  • When connection-oriented routing is needed, both TCP and IP are used. TCP establishes the virtual circuit and IP routes the messages.
  • When connectionless routing is desired, only IP is needed, and the TCP packet is replaced with a User Datagram Protocol (UDP) packet.
connectionless vs connection oriented routing30
Connectionless vs. Connection-Oriented Routing
  • IPX/SPX can also operate as either as connection-oriented or connectionless.
  • When connection-oriented routing is needed, both IPX and SPX are used. SPX establishes the virtual circuit and IPX routes the messages.
  • When connectionless routing is desired, only IPX is needed.
quality of service qos routing
Quality of Service (QoS) Routing
  • Special kind of connection-oriented dynamic routing
  • Packets are assigned different priorities
    • Depending on the type of packet sent
    • Different classes of service are defined to determine the priority
  • Transport layer specifies the class of service when requesting virtual circuit
  • Each path designed to support different service classes
  • Qos protocols
    • Rsvp
    • Rtsp
    • Rtp
addressing
Addressing

Key Concept

Each computer has

several addresses, each

used by a different layer.

Example

Address

Example

Software

Address

Application Layer

Web Browser

www.cob.niu.edu

Network Layer

IP

131.156.120.128

Data Link Layer

00-0C-00-F5-03-5A

Ethernet

assigning address
Assigning Address
  • At the application layer
    • Server names are specified in a software configuration file
    • Most servers have an application address, clients are beginning to depending on the operating system
    • A network standards group must approve all server names to insure that the addresses are unique
assigning address34
Assigning Address
  • At the Network Layer
    • Network layer software has a configuration file that specifies the network layer address for the computer
    • Every network has a standards group that defines what addresses can be used by each organization
assigning address35
Assigning Address
  • At the data link layer
    • Address is permanently coded in each network card
    • Every network card in the world has a unique address that differs from every other computer in the world
    • Addresses are coded by the vendor
icann
ICANN
  • Internet corporation for assigned names and numbers (ICANN)
    • Manages the assignment of application layer and network layer addresses
    • Sets the rules by which new domain names are created and IP address numbers are assigned
    • Manages a set of internet domains
    • Authorizes private companies to become domain name registrars
      • Approves request for application layer addresses and assigns IP numbers for those request
      • Organizations can use any registered company for the specific domain for a fee
addressing37
Addressing

Dotted

Decimal

Notation

IPv4 address is four bytes long

Address

Class

0

7 8

31

Host

number

Network

number

1.0.0.0 to

126.0.0.0

A

0

16 million user addresses

15 16

31

0

1

128.1.0.0 to

191.254.0.0

B

Network

number

Host

number

1

0

65,000 user addresses

0

1

31

23 24

192.0.1.0 to

223.255.254.0

Network

number

Host

number

C

1

1

0

254 addresses

Assigned by ICANN

subnets
Subnets
  • Each organization assigns IP addresses to specific computers on its networks
  • IP addresses are assigned so that all computers on the same LAN have similar addresses
  • Each of these lans is known as a TCP/IP subnet
  • Any portion of the IP address can be designated as a subnet using a subnet mask*

* Subnet masks tell computers what part of an IP address is to be used to

determine whether a destination is on the same or a different subnet

subnet addressing40
Subnet Addressing

Example 1

Suppose that the first two bytes are the subnet indicator with addresses of the form 131.156.x.x

Then, 131.156.29.156 and 131.156.34.215 would be on the same subnet.

The subnet mask would be 255.255.0.0, which corresponds to 11111111.11111111.00000000.00000000, where 1 indicates that the position is part of the subnet address and a 0 indicates that it is not.

subnet addressing41
Subnet Addressing

Example 2

Partial bytes can also be used as subnets.

For example, consider the subnet mask 255.255.255.128, which is 11111111.11111111.11111111.10000000.

Here, all computers with the same first three bytes and last byte from 128 to 254 would be on the same subnet.

providing addresses
Providing Addresses
  • Providing addresses to networked computers
    • Static addressing
    • Dynamic addressing
static addressing
Static Addressing
  • Each computer is given an address through a configuration file
  • Stored on individual computers
  • Problems
    • Moves, changes, adds and deletes
    • Individuals could change their own IP address
    • Network renumbered
  • Companies do not have a good way of tracking the addresses
dynamic addressing
Dynamic Addressing
  • Server supplies a network layer address automatically
    • Each time user logs in
    • For a specific lease period
  • Two standards for dynamic addressing
    • Bootstrap protocol (bootp) - developed in 1985
    • Dynamic host control* protocol (DHCP), developed in 1993

* some say C = configuration

dynamic addressing45
Dynamic Addressing
  • Bootp and DHCP
    • Software installed on the client instructs the client to contact the server using data link layer addresses
    • Message asks server to assign the client a unique network layer address
    • Server runs corresponding software that sends the client its network address and subnet mask
leasing
Leasing
  • Bootp or DHCP server can either:
    • Assign the same network layer address to the client each time the client requests it (bootp)
    • Lease the network address from the next available on a list of authorized addresses for as long as the client is connected or for a specified amount of time -- common with isps and dial-up users (DHCP)
address resolution
Address Resolution
  • The process of:
    • Translating an application layer address to a network address (server name resolution)
    • Translating the server name address to a data link layer address (data link layer address resolution)
address resolution48
Address Resolution
  • Server name resolution
    • Accomplished by the use of domain name service (DNS)
    • Computers called name servers provide these DNS services
      • Address data base includes: server names and their corresponding IP address
slide49

Weber State University

DNS Server

sol.acs.unt.edu

137.90.2.122

DNS Response

DNS Request

Client

computer

LAN

DNS Request

DNS Response

Root DNS Server

for .EDU

domain

Internet

DNS Request

Northern Illinois University

DNS Server

netmgr.cso.niu.edu

131.156.1.11

LAN

DNS Response

Figure 5-7

address resolution50
Address Resolution
  • Data link layer address resolution
    • Broadcast message is sent to all computers in its subnet
      • “if your IP address is xxx.Yyy.Zzz.Ttt, please send your data link layer address”
      • Uses address resolution protocol (ARP)
network routing
Network Routing
  • The process of determining the route a message will take through the network
    • Centralized
    • Decentralized
      • Static routing
      • Dynamic routing
      • Broadcast or multicast routing
    • Connectionless
    • Connection-oriented routing
route and route table
Route and Route Table

C

B

Computer B

Destination Route

A A

C C

D A

E E

F E G C

G

A

F

D

E

internet routes

WSU

Canada

Other destinations

UEN

Asia

Europe

West Coast

Internet Routes

WSU

Destination Route

UEN Utah

Oxford Europe

U of Toronto Canada

U of Singapore Asia

UC Stanford West Coast

Other Other

types of routing
Types of Routing
  • Centralized routing
  • Static routing (decentralized)
  • Dynamic routing (adaptive and decentralized)
    • Distance vector
    • Link state
  • Other types
    • Broadcast routing
    • Multicast routing
centralized routing
Centralized Routing
  • All routing decisions are made by one computer
  • Main routing for star and mesh topologies
  • Routing tables located on each computer
    • Central computer sends updated tables as needed
    • Routing table tells the device where to send messages
  • Simplicity - no wasted resources
  • Hardware failures or changing conditions cause table to be out of sync
decentralized routing
Decentralized Routing
  • Each of the following types of routing fall under the heading of decentralized routing
  • Each device makes its own routing decisions with the use of a formal routing protocol
  • Routing protocols are self-adjusting
    • Can automatically adapt to changes in the network configuration
  • Drawbacks
    • Slows down the network with status messages
    • Requires more processing by each computer
static routing
Static Routing
  • Routing table developed by the network manager or some type of committee
    • Initial table sent to each computer which then updates the routing table as needed
    • Reroutes as needed with down or removed circuits
    • Updated when new devices announce their presence
    • Used in relatively static networks that have few routing options
dynamic routing adaptive
Dynamic Routing (Adaptive)
  • Routing messages over the fastest route
    • Used when there are multiple routes in the network
    • Improves network performance by selecting the fastest route to avoid bottlenecks or busy circuits
    • Initial table developed by network manager
    • Dynamically updated with changing conditions by the devices themselves
    • Monitors message transmission time or each device reports how busy it is to avoid bottlenecks
  • Disadvantages
    • Requires more processing by each computer
    • “Wastes” network capacity
dynamic routing adaptive59
Dynamic Routing (Adaptive)
  • Distance vector dynamic routing
    • The number of hops along a route
    • Exchange information with the neighboring computers every few minutes
  • Link state dynamic routing
    • The number of hops along a route
    • The speed of the circuits on the route
    • How busy the route is
    • Exchanges information with other routing devices every 15-30 minutes
    • Tries to determine the fastest route
    • Converges reliable routing information more quickly
routing protocols
Routing Protocols
  • RIP, IGP, OSPF, EGP, BGP
  • Distance vector routing protocols (RIP, Appletalk,IPX, IGRP)
    • Routers inform neighboring routers of table
    • Closest router is used to route packets
  • Link State routing protocols (OSPF)
    • Routers have at least a partial map of the network
    • Changes are flooded throughout network
    • Routes are recomputed
interior and exterior routing
Interior and Exterior Routing
  • Interior routing is within an autonomous system (collection of routers under a single administrative control)—RIP, OSPF
  • Exterior routing occurs between autonomous systems
  • Network access protocols operate at Layer 2.
    • Transport of IP datagrams
    • IP over point-to-point connections is used by ISP when you dial in
routing protocols62
Routing Protocols
  • Border Gateway Protocol
  • Internet Control Message Protocol
  • Routing Information Protocol
  • Open Shortest Path First
  • Enhanced Interior Gateway Routing Protocol
routing protocols63
Routing Protocols
  • Internet protocols
    • BGP (border gateway protocol)
      • Exchanges information between autonomous systems about the condition of the internet
      • Complex, hard to administer, exterior routing protocol
    • ICMP (internet control message protocol)
      • Simple, interior routing protocol used with the internet
      • Reports routing errors but is limited in the ability to update
    • RIP (routing information protocol)
      • Dynamic distance vector interior routing protocol
      • Counts the number of devices on each route
      • Selects the route with the least number of devices
routing protocols64
Routing Protocols
  • OSPF (open shortest path first)
    • Link state interior routing protocol used on the internet
    • Counts number of computers, network traffic, network error rates to select the best route
    • Doesn’t broadcast to all devices just to routing devices
    • Preferred TCP/IP, but also used by IPX/SPX
  • EIGRP (enhanced interior gateway routing protocol)
    • Link state interior routing protocol developed by CISCO
    • Uses route transmission capacity, delay, reliability and load to select best route
    • Stores multiple routing tables
  • SAP (service advertisement protocol)
    • Netware servers send SAP advertisements
    • Novell’s broadcast protocol
broadcast routing
Broadcast Routing
  • Sends the message to all computers on the network
  • Only computer with correct address processes the message
  • Used only in bus networks
  • Wastes network bandwidth
multicasting
Multicasting
  • Similar to broadcasting
  • Only works within one LAN or subnet
  • Messages sent from one computer to another on the network is called a unicast message
  • Messages sent to a group of computers is called a multicast message
  • Targeting a specific work group
  • IGMP (internet group management protocol)
    • Sends an IGMP multicast request to the routing computer
    • Assigned a special class D IP address to identify the group
    • The routing computer sets the data link layer address
    • All participating machines will process messages sent to this address
    • Sends a IGMP message notifying of end of session
figures and tables
Figures and Tables
  • P. 245 figures 9.2 & 9.3
  • P. 261 figure 9.7