Chapter 2

TCP/IP Protocol

Contents What Is TCP/IP (ok) The Birth of TCP/IP(ok) Design Goals of TCP/IP (ok) Moving Data across the Network(ok) What Are Protocols(ok) The OSI Reference Model (ok) TCP/IP and the DoD Model (ok) The Network Interface Layer(ok) The Internet Layer (ok) The Transport Layer(ok) The Application Layer(ok) IP Addressing(ok) Addressing IP Hosts(ok) Subnet Masks (ok) Custom Subnet Masks(ok) Supernetting and CIDR(ok) IP Version 6

What Is TCP/IP

TCP/IP is a set of protocols that enable communication between computers.

Features of TCP/IP◦ Support from Vendors: TCP/IP receives support from many hardware

and software vendors.◦ Interoperability: it can be installed and used on virtually every

platform.◦ Flexibility: An administrator can automatically or manually assign an

IP address to a host, and a TCP/IP host can convert easy-to-remember names.

◦ Routability: TCP/IP is exceptionally well adapted to the process of routing data from one segment of the network to another, or from a host on a network in one part of the world to a host on a network in another part of the world.

The Birth of TCP/IP

1969 1974

-NCP Protocol-Birth TCP to replace NCP-host-to-host portion of a communication

1978

-TCP/IP birth

1982

-it was decided that TCP/IP would replace NCP as the standard languageof the ARPAnet.

1983

-ARPAnet switched over to TCP/IP.

1990

-TCP/IP has evolved to meet the changing requirements ofthe Internet

Design Goals of TCP/IP Hardware independence: A protocol suite that could be used on a

Mac, PC, mainframe, or any other computer. Software independence: A protocol suite that could be used by different

software vendors and applications. Failure recovery and the ability to handle high error rates: A protocol

suite that featured automatic recovery from any dropped or lost data. Efficient protocol with low overhead: A protocol suite that had a

minimal amount of “extra” data moving with the data being transferred. Ability to add new networks to the internetwork without service

disruption: A protocol suite that enabled new, independent networks to join this network of networks without bringing down the larger internetwork.

Routable Data: A protocol suite on which data could make its way through an internetwork of computers to any possible destination.

Moving Data across the Network

Moving Data on a Circuit-Switched Network: data communication moves along a single, established route.

Moving Data on a Packet-Switched Network: On a packet-switched network, the computer that is sending the data fragments the data into smaller, more manageable chunks(Packet).

Moving Data across the Network

Moving Data on a Circuit-Switched Network

Moving Data on a Packet-Switched Network

What Are ProtocolsA protocol is a rule or a set of rules and

standards for communicating that computers use when they send data back and forth.

Protocols Move Packets of DataWhy We Need Protocols and Standards

The OSI Reference ModelThe OSI model is made up of seven distinct layers:

◦ Application: is to manage communications between applications◦ Presentation: is to ensure that the message gets transmitted in a

language or syntax that the receiving computer can understand.◦ Session: It controls the dialog during communications.◦ Transport: can guarantee that packets are received.◦ Network: is responsible for routing the packet based on its

logical address.◦ Data-Link: which is where the data is prepared for final delivery

to the network.◦ Physical: determine how the sending and receiving bits of data

move along the network’s wire.

TCP/IP and the DoD ModelTCP/IP was developed using the Department of Defense

(DoD) reference model.Department of Defense (DoD) reference model has four

layers:The four layers of the DoD model are:

◦ Application: Covers the same topics as the Application, Presentation, and Session layers in the OSI model.

◦ Transport: Covers the topics of Transport from the OSI model.◦ Internet: Covers the topics of Network from the OSI model.◦ Network Interface Layer: Covers the topics of Data-Link and

Physical from the OSI model.

DoD and OSI Model

The Network Interface Layer Network Interface layer: is to define how a computer connects to a network. Feature of Network Interface Layer:

◦ The TCP/IP Network Interface layer does not regulate the type of network that the host is on.

◦ Host can be on an Ethernet, Token Ring, or Fiber Distributed Data Interface (FDDI), or on any other network topology.

◦ At the Network Interface layer, a header is applied that contains addressing information(hardware address).

◦ TCP/IP packet to be delivered, it must contain the destination’s hardware address.◦ A broadcast packet contains the target hardware address of FF:FF:FF:FF:FF:FF.

Feature of Hardware Address◦ It is a 12-character hexadecimal address ◦ The first six of these hexadecimal characters represent the manufacturer.◦ The last six characters form a unique serial number that the card’s manufacturer has

assigned to it.◦ 00:A0:C9:0F:92:A5

The Internet LayerThe Internet layer contains the protocols that are

responsible for addressing and routing of packets.The Internet layer contains several protocols, including:

◦ Internet Protocol (IP)◦ Address Resolution Protocol (ARP)◦ Internet Control Message Protocol (ICMP)◦ Internet Group Message Protocol (IGMP)

Feature of Internet layer:◦ The packet moves up to the Internet layer must contain an IP

address .◦ The Internet layer provides the necessary protocols to determine

the hardware address for routing the packet to the destination.

Internet Protocol (IP)The Internet Protocol: is the primary protocol at the Internet

layer of the TCP/IP stack that is responsible for determining the source and destination IP addresses of every packet.

A default gateway, also called a router , is the address of a host on the network that offers a route off of the network.

ARP is a protocol that can resolve an IP address to a hardware address.

ICMP is a protocol used primarily for sending error messages, performing diagnostics, and controlling the flow of data.

IGMP is a protocol that enables one host to send one stream of data to many hosts at the same time.

The protocols at the Internet layer

The Transport LayerTransport layer: is a Host-to-Host layer.The Transport layer of the TCP/IP protocol

suite consists of only two protocols:◦TCP: provides connection-oriented, reliable

communication ◦UDP: provides connectionless, unreliable

communication

TCP and UDP Header

The Application LayerThe Application layer: is the part of the TCP/IP

where requests for data or services are processed.

Feature of Application Layer:◦Application layer uses port to listening for requests

to process.◦TCP and UDP have use of 65,536 ports each.◦A socket: combines three pieces of information: the

IP address, TCP or UDP, and the port number

Host sending a request to the Web Server

IP Addressing IP address: is used to identify network and host address for sending data. Feature of IP address:

◦ IP address uniquely identifies every host on a network.◦ IP address divides in two part are Network and Host number.◦ IP addresses are based on 32-bit addresses◦ IP address has 2 version are IPV4 and IPV6◦ IP address has Classless Inter-Domain Routing (CIDR)

IP addresses are divided into five classes:◦ Class A : 1 to 127 and use the first octet to represent the unique network address and

leave three octets to develop unique host addresses on that network.◦ Class B: 128 to 191 and use the first two octets to represent the unique network address

and leave only two octets to develop unique host addresses on that network.◦ Class C : 192 to 223 and use the first three octets to represent the unique network

address and leave only one octet to develop unique host addresses on that network.◦ Class D : 224 to 239 and is used as multicast addresses (No one host) in this class◦ Class E : 240 to 255 are reserved addresses and are invalid host addresses.

How to obtain IP AddressWe have two ways to obtain IP Address to

host:◦Manual IP Address Configuration◦Obtaining an IP Address from a DHCP Server

Subnet MasksA subnet mask: is a number that looks like an IP address

that shows TCP/IP how many bits are used for the network portion of the IP address.

Feature of Subnet mask:◦TCP/IP uses the subnet mask to determine whether the

destination of a packet is a host on the local network or a host on a remote network.

◦Bit 1s represent network ID and Bit 0s represent host IDStandard subnet mask

◦Class A: 255.0.0.0◦Class B: 255.255.0.0◦Class C: 255.255.255.0

Custom Subnet Masks Custom subnet mask: is the subnet mask that is created by network

administrator. The rules for subnetting:

◦ The subnet bits in the IP address cannot be all 1s.◦ The subnet bits in the IP address cannot be all 0s.◦ The host bits in the IP address cannot be all 1s.

Creating a Custom Subnet Mask:◦ Determine how many subnets are needed◦ Determine the maximum number of hosts on each network◦ Determine the subnet mask◦ Determine the valid network addresses◦ Determine the range of valid host IP addresses on each subnet◦ Confirm that you met the requirements for the number of networks and

maximum number of hosts

Supernetting and CIDRSupernetting: is used in routing tables to

compact contiguous Class C networks.CIDR addresses: replace the subnet mask and

state the number of bits that IP should use to determine the network portion of an IP address.

To create the right supernetted subnet mask , an administrator must look at the binary and determine the last bit where all of the networks are the same.

IP Version 6 Features Of IPv6

◦ Larger Addresses: use 128bits address◦ Extended Address Hierarchy: IPv6 uses the larger address space to create

additional levels of addressing hierarchy.◦ Flexible Header Format: IPv6 uses an entirely new and incompatible datagram

format by using set of optional headers◦ Improved Options: IPv6 allows a datagram to include optional control information.◦ Provision For Protocol Extension: The extension capability has the potential to

allow the IETF to adapt the protocol to changes in underlying network hardware or to new applications.

◦ Support For Autoconfiguration And Renumbering: IPv6 provides facilities that allow computers on an isolated network to assign themselves addresses and begin communicating without depending on a router or manual configuration.

◦ Support For Resource Allocation. IPv6 has two facilities that permit preallocation of network resources: a flow abstraction and a differentiated service specification.

General Form Of An IPv6 Datagram

The Fields in the IPv6 Header

Version: containing the version of the protocol.

Traffic Class: for sending nodes and forwarding routers can use it to identify and distinguish between different classes or priorities of IPv6 packets.

Flow Label : Payload Length: the length of data

carried after the IP header. Next Header : this field is called the

Protocol Type field. Hop Limit : The value in this field now

expresses a number of hops. Source Address: contains the IP address

of the originator of the packet. Destination Address : This field

contains the IP address of the intended recipient of the packet.

Extension Headers Hop-by-Hop Options Header:

carries optional information that must be examined by every node along the path of the packet.

Routing Header: is used to give a list of one or more intermediate nodes that should be visited on the packet's path to its destination.

Fragment Header: IPv6 host that wants to send a packet to an IPv6 destination uses Path MTU discovery to determine the maximum packet size that can be used on the path to that destination.

IPv6 Addressing NotationAddress Notation:

◦ An IPv6 address has 128 bits, or 16 bytes. The address is divided into eight 16-bit hexadecimal blocks separated by colons. Ex 2001:DB8:0000:0000:0202:B3FF:FE1E:8329

◦ A double colon can replace consecutive zeros or leading or trailing zeros within the address. Ex 2001:DB8::202:B3FF:FE1E:8329

◦ colon hex notation incorporates dotted decimal suffixes during the transition from IPv4 to IPv6. ex 0:0:0:0:0:0:192.168.0.2

◦ IPv6 extends CIDR-like notation by allowing an address to be followed by a slash and an integer that specifies a number of bits. 2001:DB8::56/64

IPv6 Address Types IPv6 has three types of addresses, which can be categorized by type

and scope:◦ Unicast addresses: A packet is delivered to one interface.◦ Multicast addresses: A packet is delivered to multiple interfaces.◦ Anycast addresses: A packet is delivered to the nearest of multiple

interfaces (in terms of routing distance). IPv6 does not use broadcast messages.Unicast and anycast addresses in IPv6 have the following scopes (for

multicast addresses, the scope is built into the address structure):◦ Link-local: The scope is the local link (nodes on the same subnet).◦ Site-local: The scope is the organization (private site addressing).◦ Global: The scope is global (IPv6 Internet addresses)

Unicast IPv6 Addresses IPv6 has several major unicast address types:

◦ Unicast global addresses: IPv6 unicast global addresses are similar to IPv4 public addresses

◦ Unicast site-local addresses: IPv6 unicast site-local addresses are similar to IPv4 private addresses.

◦ Unicast link-local addresses: use these automatically configured addresses to communicate with each other.

◦ Unicast unspecified address:The IPv6 unspecified address is 0:0:0:0:0:0:0:0:, or a double colon (::).

◦ Unicast loopback address: The IPv6 unicast loopback address is equivalent to the IPv4 loopback address.

◦ Unicast 6to4 addresses: IPv6 uses 6to4 addresses to communicate between two IPv6/IPv4 nodes over the IPv4 Internet.

◦ Unicast ISATAP addresses: IPv6 uses ISATAP addresses to communicate between two IPv6/IPv4 nodes over an IPv4 intranet.

Unicast global addresses

IPv6 unicast global addresses are similar to IPv4 public addresses. Also known as aggregatable global unicast addresses, global addresses are globally routable. The structure of an IPv6 unicast global address creates the three-level topology shown in the following illustration.

Fields in a Unicast Global Address:◦ 001 : Identifies the address as an IPv6 unicast global address.◦ TLA ID: Identifies the highest level in the routing hierarchy. TLA IDs are administered by IANA,

which allocates them to local Internet registries, which then allocate a given TLA ID to a global ISP.◦ Res: Reserved for future use (to expand either the TLA ID or the NLA ID).◦ NLA ID: Identifies a specific customer site.◦ SLA ID: Enables as many as 65,536 (216) subnets within an individual organization’s site. The

SLA ID is assigned within the site; an ISP cannot change this part of the address.◦ Interface ID : Identifies the interface of a node on a specific subnet.

Unicast site-local addresses

IPv6 unicast site-local addresses are similar to IPv4 private addresses. The scope of a site-local address is the internetwork of an organization’s site. (You can use both global addresses and site-local addresses in your network.) The prefix for site-local addresses is FEC0::/48.

Example:◦ FEC0:0:0:1::1 ◦ FEC0:0:0:1::2◦ FEC0:0:0:2::1◦ FEC0:0:0:3::2

The same Network in the site local with different interface ID

The Different Network in the site local with different interface ID

Unicast link-local addresses (FE80::/64)

IPv6 unicast link-local addresses are similar to IPv4 APIPA addresses used by computers running Microsoft Windows. Hosts on the same link (the same subnet) use these automatically configured addresses to communicate with each other. Neighbor Discovery provides address resolution. The prefix for link-local addresses is FE80::/64. The following illustration shows the structure of a link-local address.

Unicast 6to4 addresses (2002::/16)

IPv6 uses 6to4 addresses to communicate between two IPv6/IPv4 nodes over the IPv4 Internet. A 6to4 address combines the prefix 2002::/16 with the 32 bits of the public IPv4 address of the node to create a 48-bit prefix — 2002:WWXX:YYZZ::/48, where WWXX:YYZZ is the colon-hexadecimal representation of w.x.y.z, a public IPv4 address.

Example: 157.60.91.123 2002:9D3C:5B7B::/48

Unicast ISATAP addresses

IPv6 uses ISATAP addresses to communicate between two IPv6/IPv4 nodes over an IPv4 intranet. An ISATAP address combines a 64-bit unicast link-local, site-local, or global prefix (a global prefix might be a 6 to 4 prefix) with a 64-bit suffix constructed of the ISATAP identifier 0:5EFE, followed by the IPv4 address assigned to an interface of the host. The prefix is known as the subnet prefix. Although a 6to4 address can incorporate only a public IPv4 address, an ISATAP address can incorporate either a public or a private IPv4 address.

Examples of ISATAP addresses:◦ With link-local prefix: FE80::5EFE:131.107.129.8◦ With site-local prefix: FEC0::1111:0:5EFE:131.107.129.8◦ With global prefix: 3FFE:1A05:510:1111:0:5EFE:131.107.129.8◦ With global 6to4 prefix: 2002:9D36:1:2:0:5EFE:131.107.129.8

Well-Known Multicast Addresses

Interface-local scope FF01:0:0:0:0:0:0:1 All-nodes address FF01:0:0:0:0:0:0:2 All-routers address

Link-local scope FF02:0:0:0:0:0:0:1 All-nodes address FF02:0:0:0:0:0:0:2 All-routers address FF02:0:0:0:0:0:0:3 Unassigned FF02:0:0:0:0:0:0:4 DVMRP routers FF02:0:0:0:0:0:0:5 OSPFIGP FF02:0:0:0:0:0:0:6 OSPFIGP designated routers FF02:0:0:0:0:0:0:7 ST routers FF02:0:0:0:0:0:0:8 ST hosts FF02:0:0:0:0:0:0:9 RIP routers FF02:0:0:0:0:0:0:A EIGRP routers FF02:0:0:0:0:0:0:B Mobile agents FF02:0:0:0:0:0:0:D All PIM routers FF02:0:0:0:0:0:0:E RSVP encapsulation FF02:0:0:0:0:0:0:16 All MLDv2-capable routers FF02:0:0:0:0:0:0:6A All snoopers FF02:0:0:0:0:0:1:1 Link name FF02:0:0:0:0:0:1:2 All DHCP agents FF02:0:0:0:0:0:1:3 Link-local Multicast Name

Resolution FF02:0:0:0:0:0:1:4 DTCP Announcement FF02:0:0:0:0:1:FFXX:XXXX Solicited-node

address

Site-local scope

FF05:0:0:0:0:0:0:2 All-routers address

FF05:0:0:0:0:0:1:3 All DHCP servers

FF05:0:0:0:0:0:1:4 Deprecated

FF05:0:0:0:0:0:1:1000 to FF05:0:0:0:0:01:13FF Service location (SLP) Version 2