sict ii - lecture 4

TCP/IP PROTOCOL SUITE AND ROUTING FUNDAMENTALS

Mr. Froilan E. De Guzman

Introduction to TCP/IP

TCP/IP in fact consists of dozens of different protocols, but only a few are the “main” protocols that define the core operation of the suite.

The Internet Protocol (IP) is the primary OSI network layer (layer three) protocol that provides addressing, datagram routing and other functions in an internetwork.

The Transmission Control Protocol (TCP) is the primary transport layer (layer four) protocol, and is responsible for connection establishment and management and reliable data transport between software processes on devices.

TCP/IP Protocol Suite Layers and OSI Layers

IPv4 vs. IPv6

Example of IPv4 (32-bits) 00110001.10000110.11000001.00000011 33.134.193.3

Example of IPv6 (128-bits) 0011111111111110:0001100100000000: 0110010101000101:0000000000000011: 0000001000110000:1111100000000010: 0111111010111111:0001001011000010 3FFE.1900.6545.3.230.F804.7EBF.12C2

Application Layer

The last layer of both the OSI and the TCP/IP model.

It is the closest to the end user when interacting with software applications, such as sending and receiving email over a network

Domain Name System

Domain is a group of computers that are associated with geographical location or their business types

Geographic Locations - .us, .uk, .ph Business Types:

.edu – educational sites - .com – Commercial sites .gov – Government sites - .org – Nonprofit sites .net – Network service - .mil – US military sites .int – International database/treaty organizations sites

FTP and TFTP

FTP – is designed to download and upload files. The main purpose of this is transfer files from one computer to another.

TFTP – it is connectionless service that uses UDP. It is used on routers and switches to transfer configuration files and to transport files that supports TFTP

Hypertext Transfer Protocol

It works with the world wide web, which is the fastest-growing and most used part of the Internet.

URL components: http:// - Identifies to the browser what protocol

should be used www. – Identifies what type of site is being

contacted by the browser Yahoo.com – Represents the domain entry of

the website /cgi/r3/ - Identifies the folder where the web

page is located on the server. Also, because no name is specified, the browser loads the default page identified by the server.

Simple Mail Transfer Protocol It transport email messages in ASCII

format using TCP. You can connect to an SMTP server by

performing a ping test to the SMTP port (25) or to the POP3 port (110).

Simple Network Management Protocol It is an application layer protocol that

facilitates the exchange of management information between network devices.

It enables network administrators to manage network performance, find and solve network problems and plan for network growth.

Key Components of SNMP

Managed Device – It collect and store management information and make this information available to NMSs using SNMP.

Agent – It has local acknowledgement of management information and translates that information into a form compatible with SNMP.

Network Management System (NMS) – It provides the bulk of the processing and memory resources requires for network management

Terminal Emulation

It provides the capability to remotely access another computer.

It enables you to log in to an Internet host and execute commands.

It commonly used for remote administration of servers and network equipment such as routers and switches.

Transport Layer

It provides transport services from the host to the destination host.

It constitutes a logical connection between the endpoints of the network.

Transport services segments and reassemble data that is sent by several upper-layer applications onto the same transport layer data stream.

Transport layer data stream is a logical connection between the endpoints of a network.

Transport Layer Protocols

Transport services using TCP include all the following services whereas using UDP provides only the first two Segmenting upper-layer application data Sending segments from one end device to

another end device Establishing end-to-end operations Flow control provided by sliding windows Reliability provided by sequence numbers and

acknowledgments.

Flow Control

It avoids the problem of a transmitting host overflowing buffers in the receiving host.

Overflow can represent serious problems because they can result in the loss of data

Establishing Connection

Sender Receiver

Synchronize

Synchronize

Negotiate Connection

Acknowledgement

Connection EstablishedData Transfer (Send Segments)

Three-way Handshake

A sequence of messages exchanged between two or more network devices to ensure transmission synchronization before sending user data.

Windowing

A flow-control mechanism requiring that the source device receive an acknowledgement from the destination after transmitting a certain amount of data.

Acknowledgement

Notification sent from one network device to another to acknowledge that some vent occurred.

Sometimes abbreviated ACK

Transmission Control Protocol It is a connection-oriented transport layer

protocol that provides reliable full-duplex data transmission

It is part of TCP/IP protocol stack. TCP is responsible for breaking messages

into segments, reassembling them at the destination station, resending anything that is not received, and reassembling messages from the segments

Protocols Use TCP

File Transfer Protocol Hypertext Transfer Protocol Simple Mail Transfer Protocol Domain Name System

TCP Segment Fields

Source Port – Number of calling port Destination Port – Number of called port Sequence Number – Number used to

ensure correct sequencing of the arriving data

Acknowledgement Number – Next expected TCP octet

HLEN – Number of 32-bit words in the header

Reserved – Set to 0 Code Bits – Control functions (such as

setup and termination of a session)

TCP Segment Fields

Window – Number of octets that the sender is willing to accept

Checksum – Calculated checksum of the header and data fields

Urgent Pointer – Indication of the end of the urgent data

Options – One option currently defined – maximum TCP/IP segment size

Data – Upper-layer protocol data

User Datagram Protocol

It is connectionless transport protocol in the TCP/IP protocol stack

It is a simple protocol that exchanges datagrams without acknowledgements or guaranteed delivery.

Protocols Use UDP

Trivial File Transfer Protocol Simple Network Management Protocol Dynamic Host Configuration Protocol Domain Name System

UDP Segment Fields

Source Port – Number of calling port Destination Port – Number of called

port Length – Number of bytes, including

header and data Checksum – Calculated checksum of

the header and data fields Data – Upper-layer protocol data

Reserved TCP and UDP Port Numbers

Decimal Port

Number

Keyword Description

0 - Reserved

1 to 4 - Unassigned

5 RJE Remote Job Entry

7 Echo Echo

9 Discard Discard

11 Users Active Users

13 Daytime Daytime

15 NetStat Who is up, or netstat

17 Quote Quote of the Day

Reserved TCP and UDP Port Numbers

Decimal Port

Number

Keyword Description

19 Chargen Character Generator

20 FTP-data File Transfer Protocol (Data)

21 FTP File Transfer Protocol

23 Telnet Terminal Connection

25 SMTP Simple Mail Transfer Protocol

37 Time Time of the Day

39 RLP Resource Location Protocol

42 NameServer Host name server

43 nickname Who is 

Reserved TCP and UDP Port Numbers

Decimal Port

Number

Keyword Description

53 Domain Domain Name Server

67 Bootps Bootstrap protocol server

68 Bootpc Bootstrap protocol client

69 TFTP Trivial File Transfer Protocol

75 - Any private dial-out service

77 - Any private RJE service

79 Finger Finger

80 HTTP Hypertext Transfer Protocol

95 SUPDUP SUPDUP Protocol

Reserved TCP and UDP Port Numbers

Decimal Port

Number

Keyword Description

101 HOSTNAME NIC Host Name Server

102 ISO-TSAP ISO-TSAP

113 AUTH Authentication Service

117 UUCP-PATH UUCP Path Service

123 NTP Network Time Protocol

133 to 159 Unassigned

160 to 223 Reserved

224 to 241 Unassigned

242 to 255 Unassigned

Internet Layer

The purpose of the Internet Layer is to send packets from the device using correct protocol that function at this layer.

Best path determination and packet switching occur at this layer

Internet Layer Protocol

IP - Provides connectionless, best-effort delivery routing of packets. IP is not concerned with the content of the packet. Instead, it looks for a way to move the packets to their destination.

Internet Control Message Protocol (ICMP) – Provides control messaging capabilities.

Internet Layer Protocol

Address Resolution Protocol (ARP) - Determines the data link layer addresses (MAC address) for known IP address.

Reverse Address Resolution Protocol (RARP) - Determines IPS addresses when data link layer addresses (MAC address) are known.

IP Performs the Following:

Defining a packet and an addressing scheme

Transferring data between the Internet Layer and the Network Access Layer

Routing Packets to remote hosts

Network Access Layer

It is also called the host-to-network layer. It is the layer that is concerned with all the

issues than an IP packets requires to make a physical link to the medium

It includes the LAN and WAN technology details and all the details contained in the OSI physical and data link layer

Network Access Layer Protocols

Ethernet Fast Ethernet SLIP and PPP FDDI ATM, Frame Relay and SMDS ARP Proxy ARP RARP

TCP/IP versus OSI (similarities) Both have layers Both have application layers, although

they include very different services Both have comparable transport and

network layers Packet-switched (not circuit-switched)

technology is assumed Networking professional need to know

both

TCP/IP versus OSI (differences)

TCP/IP combines the presentation and session layers into its application layer

TCP/IP combines the OSI data link and physical layers into its network access layer.

TCP/IP appears simpler because it has fewer layers.

TCP/IP transport layer using UDP does not always guarantee reliable delivery of packets, as the transport layer in the OSI model does

Internet Architecture

Internet is a deceptively simple idea that, when repeated on a large scale, enables nearly instantaneous worldwide data communications between anyone, anywhere at anytime.

Limitation of LANs is that they don’t scale

Beyond a certain number of stations

Beyond a certain geographic separation

Internet Architecture

The details of host computers, and LANs on which they reside, are separate from the details of getting messages from one network to another

The big-picture architecture for the Internet was to focus on the application layer interactions between the source and destination computers and any intermediate computers

Concept of Internetworking

Building networks of networks A network of networks is called an

“internet”. The network that grew out of the DoD on

which the WWW runs is called “Internet”.

Internetworking Characteristics

It must be scalable in the number of networks and computers attached.

It must be able to handle the transport of data across vast distances, including entire earth and near-end space.

It must be flexible to account for constant technological innovations.

It must adjust to dynamic conditions on the network.

It must be cost-effective It must be a system that permits anytime,

anywhere data communications to anyone.

IP Addressing

A 32-bit IP address is broken into a network part and a host part. A bit or bit sequence at the start of each address determines the address’s class

Hierarchical IP Address

Internet Address

1.0.0.0 2.0.0.0 3.0.0.0

10.1.0.0

50.0.0.0. . . . . . 255.0.0.0

10.3.0.010.2.0.010.4.0.0

10.0.0.0

10.5.0.0 10.255.0.0. . .

10.2.1.0 10.2.2.0 10.2.3.0 10.2.255.0

. . .. . .10.4.1.0 10.4.2.0 10.4.3.0 10.4.255.

0

IP Address Class

Address Class

Number of Networks

Number of Hosts/

Network

A 126 16,777,216

B 16,384 65,535

C 2,097,152 254

D (multicast)

Class A Addresses It was designed to support extremely

large networks. It uses only the first octet to indicate the

network addresses 127.0.0.0 network is reserved for

loopback testing, it cannot be signed to a network.

Any address that has value between 1 and 126 in the first octet is a Class A address.

Class B Addresses

The first 2 bits of the first octet of a class B addresses are always 10.

The remaining 6 bits may be populated with either 1s or 0s.

Therefore the lowest number that can be represented with the class B is 10000000 (128), and the highest is number is 10111111 (191).

Any address that starts with a value in the range of 128 to 192 in the first octet is Class B address

Class C Addresses

A Class C address begins with binary 110.

The lowest number that can be represented is 11000000 (192) and the highest number that can be represented is 11011111 (223).

If an address contains a number in the range of 192 to 223 in the first octet is Class C address.

Class D Addresses

The Class D address space, much like the other address space, is mathematically constrained.

The first 4 bits of a Class D must be 1110.

The first octet range is 11100000 to 11101111, or 224 to 239.

Class E Addresses

The first 4 bits of the first octet is 1111 The octet range is 11110000 to

11111111 (240 to 255) Class E addresses are reserved for IETF

(Internet Engineering Task Force) research.

Reserved IP Address

Network Address are used to identify the network itself.

Broadcast address are used to broadcast packets to all devices on a network.

Public IP Address

It is unique. No two machines that connect to public

network can have the same IP address. Because public IP are global and

standardized. Public IP addresses must be obtained

from an Internet service provider or a registry at some expense

Private IP Address

RFC 18 sets aside three blocks of IP addresses for private, internal use.

Addresses are not routed on the Internet backbone, Internet routers immediately discard private IP addresses

Private IP Addresses

IP Address Class RFC 1918 Internal Address Range

Class A 10.0.0.0 to 10.255.255.255

Class B 172.16.0.0 to 172.31.255.255

Class C 192.168.0.0 to 192.168.255.255

Introduction to Subnetting

The way to conserve IP address. This method of dividing full network

address classes into smaller pieces has helped prevented complete IP address exhaustion

Obtaining IP Address

Static Addressing RARP Addressing BOOTP Addressing DHCP Addressing

Static Addressing

Each device must be configure with an IP address.

RARP Addressing

It is a process wherein MAC address binding into IP addresses which allows some network devices to encapsulate data before sending it out on the

BOOTP Addressing

It operates in a client/server environment and requires only a single packet exchange to obtain IP information

DHCP Addressing

Dynamic Host Configuration Protocol is the successor of BOOTP. It allows to obtain an IP address dynamically without the network administrator’s having to set up an individual profile for that machine.

What is Protocol?

It is standards-based set of rules that determines how computers communicate with each other across networks.

It also serves as the common denominator or medium by which different applications, hosts or systems communicate

A Protocol Describes

The format that a message must take The way in which computers must

exchange a message within the context of a particular activity, such sending messages across networks.

Routed Protocol

Any network protocol that provides enough information in its network layer address to allow a packet to be forwarded from one host to another based on the addressing scheme.

It defines the field formats within a packet.

Example of Routed Protocols Internet Protocol Internetwork Packet Exchange AppleTalk

Routing Protocol

It supports a routed protocol by providing mechanisms for sharing routing information.

Its messages move between router It allows the routers to communicate

with other routers to update and maintain tables

Example of Routing Protocol

Routing Information Protocol Interior Gateway Routing Protocol Enhanced Interior Gateway Routing

Protocol Open Shortest Past First

Connectionless

Data transfer without the existence of a virtual circuit.

It means that no dedicated circuit connection is required, as there would be for a telephone call.

The destination is not contacted before a packet is sent.

The recipient is not contacted before a letter is sent from one destination to another.

Connection-Oriented

Data transfer that requires establishment of a virtual circuit.

It is established between the sender and the recipient before any data is transferred.

You place a call, a connection is established and the communication occurs

All packets travel sequentially across the same physical circuit.

Encapsulation Changes in a Router

Receive Frame on Interface

Is a DataFor Router?

DiscardData

End

Is CRCCheck valid?

Remove frameHeader andTrailer from

Packet

ExtractDestinationIP address .from Packet

Is PacketTo be

Routed?

Process PacketOn the Router.Send Response

CompareDestination IPWith Routing

Table

Is thereA match?

Is thereA DefaultRouter?

Forward the dataPacket to the

Interface in theRouting Table Entry

Encapsulate theData PacketWith the newCRC trailer

EncapsulateThe Data Packet

In the appropriateFrame Header

Forward theNew Frame

End

DiscardData

Send ReplyMessage

DestinationUnreachable

Anatomy of an IP Packet

Version – A 4 bit field that indicates the version of IP currently used. All devices must be running the same version of IP, or the device that is different rejects the packets.

IP Header Length (HLEN)– A 4-bit field that indicates the datagram header length in 32-bit words. This is the total length of all header information, accounting for the two variable length header fields.

Anatomy of an IP Packet

Type of Service (TOS) – An 8-bit field that specifies the level of importance that has been assigned by a particular upper-layer protocol.

Total Length – A 16-bit field that specifies the length of the entire packet in bytes, including the data and header. To get the length of the data payload, subtract the HLEN from the total length

Identification – A 16-bit field that contains an integer that identifies the current datagram, this is sequence number

Anatomy of an IP Packet

Flags – A 3-bit field in which the 2 low-order bits control fragmentation. The first bit specifies whether the packet can be fragmented, and the second bit specifies whether the packet is the last fragment in a series of fragmented packets.

Fragment Offset – A 13-bit field that helps piece together datagram fragments. This field allows the Flag field to end at a 16-bit boundary.

Anatomy of an IP Packet

Time-To-Live (TTL) – An 8-bit field that maintains a counter that gradually decreases, in increments, to 0. At this point, the datagram is discarded, keeping the packets from looping endlessly.

Protocol – An 8-bit field that indicates with upper-layer protocol receives incoming packets after IP processing has been completed

Header Checksum – A 16-bit field that helps ensure IP header integrity

Source IP Address – A 32-bit field that specifies the sending node IP address.

Destination IP Address – A 32-bit field that specifies the receiving node IP address.

Anatomy of an IP Packet

Option – A variable length field that allows IP to support various options, such as security.

Padding – Extra 0s are added to this field to ensure that the IP header is always a multiple of 32-bits

Data – A variable-length (maximum of 64KB) field that contains upper-layer information

Routing

It is an OSI Layer 3 function. It functions as a hierarchical organization

scheme that allows individual addresses to be grouped and treated as a single unit until the individual address is needed for final delivery of the data.

It is the process of finding the most efficient path from one device to another

Two functions of the Router

To maintain routing tables and make sure other routers know of changes in the network topology. This function is performed using routing protocol to communicate network information to other routers.

When packets arrive at an interface, the router must use the routing table to determine where to send the packets. It switches them to the appropriate interface, adds the necessary framing for the interface and then transmits the frame.

Routed Protocol Operation

It includes any network protocol suite provides enough information in its network layer address to allow a router to forward it to the next device and ultimately to its destination.

It defines the format and use of the fields within a packet. Packets generally are conveyed from end system to end system.

Routing Protocol Operation

It provides processes for sharing routing information

It allows routers to communicate with other routers to update and maintain the routing tables.

Routing Table Components

Protocol Type – The type of routing protocol that created the routing table entry.

Destination/Next hop associations – Tells the router that a particular destination is either directly connected to the router or that it can be reached via another router called the next hop on the way to the final destination.

Routing Metrics – These are used to determine a route’s desirability.

Outbound Interface – The interface that the data must be sent out to reach the final destination

References:

CCNA 1 and 2 By CISCO PRESS

END OF CCNA MODULE I