2001 copyright scut dt&p labs 1 the principle of tcp/ip part 1

2001 Copyright 2001 Copyright SCUT DT&P LabsSCUT DT&P Labs 1

The Principle of TCP/IPThe Principle of TCP/IP

Part 1Part 1


1. History of TCP/IP

1969: ARPANET went into operation

four packet-switched nodes at three different sites

connected together via 56 kbit/s circuits

using the Network Control Protocol (NCP)

funded by the U.S. Department of Defence

1974: TCP/IP designed by Vinton G. Cerf and Robert E.

Kahn

1979: IP version 4 documented


1. History of TCP/IP (Contd)

1979: the Internet Control and Configuration Board

(ICCB) formed

1979: BSD Unix with TCP/IP supplied to Universities

1980: ARPA started converting machines to TCP/IP

1983: mandate that all computers connected to

ARPANET use TCP/IP

1983 ARPANET split into two separate networks,

ARPANET for further research

MILNET for the military


1985: the ARPANET was heavily used and congested 1986: NSFNET developed to replace ARPANET

universities and research organisations connected to regional networks

regional networks connected to a main backbone six nationally funded super-computer centres connected

to backbone The original links were 56 kbit/s.

1988: Links upgraded to T1 (1.544 Mbit/s) The NSFNET T1 backbone connected a total of 13 sites

1991: NSF decided to move the backbone to a private company

1993: New Internet backbone, ANSNET, with T3 (45 Mbit/s) links



• 1993 NSF Solicitations 1993 NSF Solicitations four separate projects for which proposals were invited:

Create a set of Network Access Points (NAPs)

Implement a Route Arbiter

Provide a very high-speed Backbone Network Service

(vBNS)

Transition existing “regional” networks



2. Today's Internet Distributed architecture operated by commercial Network

Service Providers (NSPs) Connected together at Network Access Points (NAPs)

high-speed switch to which a number of routers can be connected for the purpose of traffic exchange

allows Internet traffic from the customers of one provider to reach the customers of another provider.

ISPs provide Internet services to end customers Connection point between a customer and an ISP is called a

point of presence (POP) ISP networks exchange information with each other by

connecting to NSPs that are connected to NAPs, or by connecting directly to NAPs


3. Internet Architecture Board (IAB) 3. Internet Architecture Board (IAB) OrganisationOrganisation

The IAB organisation

The IAB Board

IESG

Research groups Working groups

IRTF IETF


4. Active IETF (Internet Engineering Task Force) Working Groups

Applications

Internet

Operations and Management

Routing

Security

Transport

User services

General


5. Active IRTF (Internet Research Task Force)

Research Groups End-to-End Information Infrastructure Architecture Internet Resource Discovery Network Management Reliable Multicast Routing Secure Multicast Services Management


6. Internet Assigned Number Authority 6. Internet Assigned Number Authority (IANA)(IANA)

IANA

RIPE Reseaux IP Europeen

APNIC AsiaPacificNetworkInformation Centre

ARIN American Registry for Internet Numbers


DraftPaper

RFCSpec

ProposedStandard

Standard

Review by IETF and IESG not to exceed two years

IESG recommends promotion to proposed standard. RFC publishes as RFC. Otherwise it is sent back to the IETF work group.

Implementation and test for a minimum of 6 months

DraftStandard

Evaluation of implementation for a minimum of 4 months

7. RFC Standards Track Process


IESG - Internet Engineering Steering Group

The Internet Engineering Steering Groupforms part of the IETF (Internet Engineering Task Force) and is comprised of theIETF Chairman and the Area Managers of each of the associated working groups.


8. Internet Protocol Suite and OSI 8. Internet Protocol Suite and OSI Reference ModelReference Model

DATA LINK

PHYSICAL

NETWORK

TRANSPORT

SESSION

APPLICATION

PRESENTATION

NETWORK INTERFACE(LAN - ETH, TR, FDDI)

(WAN - Serial lines, FR, ATM)

INTERNET(IP, ARP, RARP)

TRANSPORT (TCP or UDP)

APPLICATION (FTP, TELNET, SNMP, DNS)

ICMP, IGMP


9. TCP/IP Protocol Stack Based on Data Flow9. TCP/IP Protocol Stack Based on Data Flow

OSPF EGP TCP UDP ICMP IGMP

IP RARPARP

RIP BGP

Ethernet, Token Ring, PPP, and so on

Telnet, FTP, TFTP,HTTP,SNMP,SMTP, and so on

Port Number

Protocol Number

Type code

Application Layer

Data LinkLayer

InternetLayer

TransportLayer


Internet Protocol (IP)Internet Protocol (IP)


1. Internet Protocol (IP)1. Internet Protocol (IP) Provides logical 32-bit network addresses

Routes data packets

Connectionless protocol

No session is established “Best effort” delivery

Reliability is responsibility of higher-layer

protocols and applications

Fragments and reassembles packets


2. IP Packet Structure

Source Address

VersionType ofService

Total LengthIHL

Identification Fragment Offset

ProtocolTime to Live Header Checksum

Destination address

PaddingOptions (variable)

32 bits (4 Bytes)

IP header is normally

20 bytes long

Flags

DATA (variable)


D T R UNUSEDPRECEDENCE

D = DelayT = ThroughputR = Reliability

2.1 Type of Service (TOS)

3 1 1 1 2



Version: the field keeps track of which version of the protocol the datagram belong to.IHL: it is provided to tell how long the header is, in 32-bit words.Type of service: the field allows the host to tell the subnet what kinds of service it wants.Identification: it is needed to allow the destination host to determine which datagram a newly arrived fragment belong to. DF: it stands for Don’t Fragment.MF: it stands for More Fragment.Fragment offset: the field tells where in the current datagram the fragment belongs.



Host A

Network Interface

IP Fires & Forgets

Reliability & Sequencing

IPRoutes

If Possible

Router

Host B

Network Interface

IP Delivers

as Received

Reliability & Sequencing

PACKET

Fragmented Packet

1. Internet Protocol (IP)1. Internet Protocol (IP)



Time to live: the field is a counter used to limit packet lifetimes.

Protocol: the field tells which transport process to give it to. TCP is one possibility, but so are UDP and some others.

Header checksum: it verifies the header only.

Source address & Destination address: they indicate the network number and host number (IP addresses).

Options: they may include Security, Strict source routing, Loose source routing, Record route, Timestamp and so on.


2.2 Fragmentation

Router1

Router2MTU =1500

IP Header Original IP Packet data area

IP Hdr 1 Data 1 IP Hdr 2 Data 2 IP Hdr 3 Data 3

MTU = 4500 bytes MTU = 4500 bytes

FDDI FDDIETHERNET

bytes



3. Traditional IP Address Classes3. Traditional IP Address Classes

CLASS A

CLASS B

CLASS C

0

1 0

1 1 0

NET ID

NET ID

NET ID

HOST ID

HOST ID

HOST ID

Number of Networks

Hosts per Network

1st Octet

Class A 126 16,777,214 1 – 126 Class B 16,384 65,534 128 – 191 Class C 2,097,152 254 192 - 223


3. Traditional IP Address Classes

1 1 10 Group Identification

Class D Used for multicast group usage - first 4 high-order bits are

1110 1st Octet between 224 and 239

Class E Reserved for future use - first 5 high-order bits are 11110


4. Addressing Guidelines4. Addressing Guidelines

Network ID cannot be 127

127 is reserved for loop-back function

Network ID and host ID cannot be 255 (all bits set to 1)

255 is a broadcast address

Network ID and host ID cannot be 0 (all bits set to 0)

O means “this network only”

Host ID must be unique to the network


5. Private IP Address Space5. Private IP Address Space

10.0.0.0 - 10.255.255.255 1 “Class A”

network

172.16.0.0 - 172.31.255.255 16 “Class B”

networks

192.168.0.0 - 192.168.255.255 256 “Class C”

networks


A network (class A, B or C) is allowed to be split into several parts for internal use but still act like a single network to the outside world.These parts are called subnet.Subnet mask is employed to distinguish different subnet.

Example: one of the ways to subnet a class B network1 01 0 HostHost

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 10 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0

NetworkNetwork SubnetSubnet IP address

Subnet mask

6. Subnet 6. Subnet


6.1 Subnet Mask6.1 Subnet Mask Blocks out a portion of the IP address to distinguish

the Network ID from the host ID Specifies whether the destination’s host IP address

is located on a local network or on a remote network.

The source’s IP address is ANDed with its subnet mask. The destination’s IP address is ANDed with the same subnet mask. If the result of both ANDing operations match, the destination is local to the

source, that is, it is on the same subnet.

6. Subnet 6. Subnet


6.2 Subnet Mask Example6.2 Subnet Mask Example For example 160.30.20.10 is on the same subnet as

160.30.20.100 if the mask is 255.255.255.0 Note: 1 AND 1 = 1. Other combinations = 0.

IP Address 10100000 00011110 00010100 00001010

Subnet Mask 11111111 11111111 11111111 00000000

10100000 00011110 00010100 00000000Result

160.30.20.10

255.255.255.0

160.30.20.0

IP Address 10100000 00011110 11001000 01100100

Subnet Mask 11111111 11111111 11111111 00000000

10100000 00011110 00010100 00000000Result

160.30.20.100

255.255.255.0

160.30.20.0

6. Subnet 6. Subnet


6.3 Subnetting6.3 Subnetting

INTERNET

PRIVATE NETWORK

160.30.0.0/24160.30.1.0/24160.30.2.0/24…………….…………….

160.30.254.0/24 160.30.255.0/24

Routing Advertisement

160.30.0.0/16

•Before subnetting: 1 network with approx.. 65 thousand hosts•After subnetting: 256 networks with 254 hosts per subnet

6. Subnet 6. Subnet


Example 1: network with customized maskExample 1: network with customized mask

Allocated IP address space 160.30.0.0/16

8 bits available for subnets and 8 bits available for host

0255 255 255

0000 00001111 1111 1111 1111 1111 1111

No. of Subnets

xxxx xxxx1010 0000 0001 1110 0000 0000160.30.0.x

xxxx xxxx1010 0000 0001 1110 1111 1111160.30.255.x

3 octet mask 255.255.255.0

Maximum of 256 subnets (28)

Network Host

6. Subnet 6. Subnet


Example 1: network with customised mask Example 1: network with customised mask (continued)(continued)


8 bits available for subnets and 8 bits available for host

0255 255 255

0000 00001111 1111 1111 1111 1111 1111

No. of hosts

0000 00011010 0000 0001 1110 xxxx xxxx160.30.x.1

1111 11101010 0000 0001 1110 xxxx xxxx160.30.x.254

3 octet mask 255.255.255.0

Maximum of 254 hosts (28 - 2)

Network Host

6. Subnet6. Subnet


Subnetting Example 2Subnetting Example 2

200.200.200.0 255.255.255.0

Network Address Subnet Mask


200.200.200.64

200.200.200.0

62 hosts per network

Note: Subnet mask for each subnet = 255.255.255.192

200.200.200.192

200.200.200.128

6. Subnet6. Subnet


Example 3: Network with Variable Length Example 3: Network with Variable Length Subnet Masks (VLSM)Subnet Masks (VLSM)

Allocated IP address space 200.200.200.0/24 want 2 subnets with 50 hosts and 8 subnets with 10 hosts?

200.200.200.0

200.200.200.0 /26 (max of 62 hosts)

200.200.200.64 /26 (max of 62 hosts)

200.200.200.192 /28 (max. of 14 hosts)200.200.200.208 /28200.200.200.224 /28200.200.200.240 /28

200.200.200.128 /28 (max. of 14 hosts)200.200.200.144 /28200.200.200.160 /28200.200.200.176 /28

Note: Subnet masks /26 = 255.255.255.192/28 = 255.255.255.240

6. Subnet 6. Subnet


Example 4: Network with VLSMExample 4: Network with VLSM

160.40.140.0 255.255.252.0

160.40.156.0255.255.255.0

160.40.152.0255.255.252.0

160.40.157.12255.255.255.252

160.40.157.4255.255.255.252

LAN 1

LAN 3

LAN 2

160.40.144.0255.255.252.0

160.40.148.0255.255.252.0

Site A

Site CSite B

160.40.156.1

160.40.140.1

160.40.152.1

160.40.157.5

160.40.157.6

160.40.157.13

160.40.157.14 160.40.148.1

160.40.144.1

6. Subnet 6. Subnet


7. Classless Inter Domain Routing (CIDR) 7. Classless Inter Domain Routing (CIDR) Route AggregationRoute Aggregation


Variable Length Subnets from 1 to 16Variable Length Subnets from 1 to 16CIDR

prefix-lengthSubnet Mask

# Individual Addresses

# Classful Networks

32 B64 B

128 B1 A or 256 Bs

2 A4 A

2 M4 M8 M

16 M32 M64 M

255.224.0.0255.192.0.0255.128.0.0

255.0.0.0254.0.0.0252.0.0.0

/11/10/9/8/7/6

/4/5

240.0.0.0248.0.0.0

16 A8 A128 M

256 M

64 A32 A

128 A1024 M512 M

2048 M 192.0.0.0224.0.0.0

128.0.0.0/2/3

/1

/16 255.255.0.0 1 B or 256 Cs65,534

4 B2 B

8 B262,142131,070

524,286255.252.0.0255.254.0.0

255.248.0.0/14/15

/1316 B1 M255.240.0.0/12

7. Classless InterDomain Routing (CIDR) Route Aggregation7. Classless InterDomain Routing (CIDR) Route Aggregation


Variable Length Subnets from 17 to 32 Variable Length Subnets from 17 to 32 CIDR

prefix-lengthSubnet Mask

# Individual Addresses

# Classful Networks

1/8 C1/4 C1/2 C1 C2 Cs4 Cs8 Cs

16 Cs32 Cs64 Cs

3062

126254510

1,0222,0464,0948,190

16,382

255.255.255.224255.255.255.192255.255.255.128

255.255.255.0255.255.254.0255.255.252.0255.255.248.0255.255.240.0255.255.224.0255.255.192.0

/27/26/25/24/23/22/21/20/19/18/17 255.255.128.0 128 Cs32,766

1/16 C14255.255.255.240/281/32 C6255.255.255.248/291/64 C2255.255.255.252/30




ISP

The INTERNET 200.25.16.0/20

200.25.16.0/24 200.25.17.0/24200.25.18.0/24200.25.19.0/24200.25.20.0/24200.25.21.0/24200.25.22.0/24200.25.23.0/24 200.25.24.0/24

200.25.25.0/24200.25.26.0/24200.25.27.0/24

200.25.28.0/24 200.25.29.0/24

200.25.30.0/24 200.25.31.0/24

200.25.16.0/21

200.25.24.0/22

200.25.28.0/23

200.25.30.0/23

200.25.0.0/16

Company ACompany B

Company C Company D


Subnet ID TablesNo. of bits

in maskSubnet Mask

255.255.255.248255.255.255.252

255.255.255.240255.255.255.224255.255.255.192255.255.255.128

255.255.255.0255.255.254.0255.255.252.0255.255.248.0255.255.240.0255.255.224.0255.255.192.0

2930

2827262524232221201918

1617

255.255.0.0255.255.128.0

Subnet IDs

0

0,16,32,48,64,80,96,112,128,144,160,176,192,208,224,240

0,8,16,24,32,40,48,56,64…………….,216,224,232,240,248

0,4,8,12,16,20,24,28,32,…………….236,240,244,248,252

0,2,4,6,8,10,12,14,16,18,…………….246,248,250,252,254

0,1,2,3,4,5,6,7,8,9,10,11,…………….251,252,253,254,255

0, 128

0, 64, 128, 192

0,32,64,96,128,160,192,224 3rdOctet

4thOctet

0, 128

0, 64, 128, 192

0,32,64,96,128,160,192,2240,16,32,48,64,80,96,112,128,144,160,176,192,208,224,240

0,8,16,24,32,40,48,56,64…………….,216,224,232,240,248

0,4,8,12,16,20,24,28,32,…………….236,240,244,248,252



The end of part 1

2001 copyright scut dt&p labs 1 the principle of tcp/ip part 1

Documents

internet control

internet traffic

internet services

new internet backbone

history of tcpip contd1979

history of tcpip contd2

main backbone

nsfnet t1 backbone