5 configuring TCP/IP

Configuring TCP/IP
PREPARED HAMEDA HURMAT

Knowing TCP/IP
Learning IP Address
Different type of IP Address
Configure IPv4 or IPv6
Understanding IP types
Understanding supernetting
Different between IPv4 and IPv6

Details of the TCP/IP Model
Application Layer The Application layer is where the applications that use the protocol stack
reside. These applications include File Transfer Protocol (FTP), Trivial File Transfer Protocol
(TFTP), Simple Mail Transfer Protocol (SMTP), and Hypertext Transfer Protocol (HTTP).
Transport Layer The Transport layer is where the two Transport layer protocols reside. These are
TCP and the User Datagram Protocol (UDP). TCP is a connection-oriented protocol, and delivery
is guaranteed. UDP is a connectionless protocol. This means that UDP does its best job to deliver
the message, but there is no guarantee.
Internet Layer The Internet layer is where IP resides. IP is a connectionless protocol that relies
on the upper layer (Transport layer) for guaranteeing delivery. Address Resolution Protocol (ARP)
also resides on this layer. ARP turns an IP address into a Media Access Control (MAC) address. All
upper and lower layers travel through the IP protocol.
Link Layer The data link protocols like Ethernet and Token Ring reside in the Link layer. This layer
is also referred to as the Network Access layer.

HowTCP/IP LayersCommunicate
When an application like FTP is called
upon, the application moves down the
layers and TCP is retrieved. TCP then
connects itself to the IP protocol and gets
released onto the network through the
Link layer

Understanding Port Numbers
TCP and UDP rely on port numbers assigned by the Internet Assigned Numbers Authority (IANA)
to forward packets to the appropriate application process.
Port numbers are 16-bit integers that are part of a message header.

Understanding IP Addressing
identifier assigned to each device on an IP network
Logical software address that designates the device’s location on the network
 All computers in the Internet understandIP.
 The main tasks of IP are:
 The addressing of the computers, and the fragmentation of packets.

There are two types of Internet Protocol:
 Internet Protocol version 4 (IPv4): currently used version ofInternet
Protocol.
 Internet Protocol version 6 (IPv6): the upcoming replacement for IPv4.It contains some
major improvements and new features.

IPv4 Address:
 An IPv4 address is a 32-bit address that uniquely and universally defines the
connection of a device (for example, a computer or a router) to the Internet.
◦ Connectionless protocol
◦ Fragments (divides) packets where necessary
◦ Addressing via 32 bit Internet addresses
 However, it contains no functions for end-to-end message reliability or flow
control. IP makes the ‘best effort’ to forward packets to the next destination, but
does not guarantee delivery because it is connectionless.

The IP address can be classify into
two classes:
 Public address:
This address considered as any valid address assigned to any user, and the organization who is
responsible for registering IP ranges called Internet Service Providers (ISPs), and this address
will be unique.
 PrivateAddress:
Any number or address assigned to a device on a private TCP/IP Local Area Network that is
accessible only within the LocalArea Network.

Internet Protocol Version 6 (IPv6)
Maintains good features of IPv4, discards bad ones.
Not compatible with IPv4
Compatible with all other Internet protocolsincluding TCP, UDP,ICMP, DNS, etc.
Main features:
–Long addresses (128 bits) ⇒ supports billions of hosts.
–Simplified, fixed size header ⇒ routers can process packets faster.
–Support for authentication and privacy
–Better support for type of service.

Internet addresses
Each network interface connected to the Internet has aunique
address consisting of two parts:
 Network address, address of the network within the Internet (used by gateways for routing IP
packets betweennetworks).
 Host address, address of the computer within the network (used for delivering packets to a
particular network interface within the network).

Internet address format
 The 32-bit IP address is separated into four 8-bit octets, allowing each octet to have a value ranging
from 0 to 255.
 Furthermore, the IP address is logically separated into two distinct components: the network ID and
the host ID. The network ID is used to identify the subnet upon which the host resides. The host ID
is used to identify the host itself within the given subnet.
 IP addresses can be displayed in three typical formats:
 Binary notation Binary notation is the format that systems on the network use to process the
address. An example of binary notation is 11000000.10101000.00000001.01100100.
 Hexadecimal notation Hexadecimal notation is the format typically used when identifying IPv6
addresses. An example of hexadecimal notation of an IPv4 address is C0.A8.01.64

Dotted-decimal notation Dotted-decimal notation is the format that is typically used for displaying the
IP address in a human-readable format. An example of dotted-decimal notation is 192.168.1.100

Classes of IP addresses
 Different networks have different sizes. Basically, there are many small
networks and few large networks.
 To provide efficient use of 32-bit address space, IPv4 defined several
address classes and associated address formats:
 Class A: allows 128 networks, 16 million hostseach.
The IP address start from 1.0.0.0 to 127.255.255.255, and the mask address is 255.0.0.0
 Class B: allows 16,382 networks, 65,534 hostseach. The IP address start from 128.0.0.0 to 191.255.255.255, and
the mask address is 255.255.0.0

Classes of IP addresses
 Class C: allows 2 million networks, 254 hosts each.
The IP address start from 192.0.0.0 to 223.255.255.255, and the mask address is 255.255.255.0
 Class D: multicast networks The IP address start from 224.0.0.0 to
239.255.255.255.
 Class E: reserved for future use. From 240 to 255 and the 255.255.255.255
used for broadcast to all the subnet.

One of the benefits of classful addresses is that they provide a hierarchy to the network through the
use of the network ID. This translates into an efficient routing environment because it is easy for a
router to determine what networks can be grouped together and treated as a single routing entry.

Private Address
 It means If the internetwork is limited to one organization, the IP addresses need only be unique
within that organization. Only networks that interface with public networks such as the Internet need
public addresses. Using public addresses on the outside and private addresses for inside networks is
very effective.
PrivateAddresses:-
RFC1918 designates three ranges of IP addresses asprivate:
 10.0.0.0 through 10.255.255.255
 172.16.0.0 through 172.31.255.255
 192.168.0.0 through 192.168.255.255

Addressing without Subnets
 If we have a class B with a Flat Network, the number of host will be more than 216=65536 hosts,
 So the problem is here, that managing this network with this number of host is too tricky and the
performance of this network will get down because of the heavy load. In other word, any single
broadcast can slowdown the network.
 Therefore, the solution is the subnetting. Subnetting means divide or separate the single
network into multiple networks that can reducethe loading from one network.
 The advantage of using subnetting is:-
1. Reduce the traffic and the increase the performance.
2. The smaller network can easier to manage.

Subnetting
 As the number of distinct local networks grows, managing them become a serious headache.
Every time a new network is installed the system administrator must contact NIC to get a new
network number.
 The solution to the problem is to allow a network to be split into several independent parts for
internal use but still act like a single network to the outside world. In the internet literature
these parts are called subnets.

Subnet masks
A mask is a 32-bit binary number that is expressed in dotted decimal notation. By default, a mask
contains two fields, the network field and the host field. These correspond to the network number
and the locally administered part of the network address. When an administrator subnets, they are
adjusting the way they view the IP address. Table 1: Default masks for classful addressing

 There three important things that should be taken into our account when we thinking about
subnetting:-
1. Network address – the first one
2. Broadcast address – the last one
3. Host addresses – everything in between
As well as, to find the number of hosts per subnet. We can use formal 2x -2,
where (x) is the number of unmasked bits (0’s) .

Example 4
An organization has purchased the Class C Address 216.21.5.0 and wouldlike
to use it to address the following 5 networks.

Supernetting
Supernetting allows you to have two or more blocks of contiguous subnetwork addresses.

VLSM
Variable Length Subnet Masking is a technique that allows network administrators to divide an
IP address space to subnets of different sizes, unlike simple same-size subnetting.
It allows network administrator to divide an IP address into subnets of different sizes.

IPv6
An IPv6 address is 128 bits long. A mask of /64 following the IP address means the first 64 bits
are the network address
128 bits (or 16 bytes) long: four times as long as its predecessor.
2128 : about 340 billion billion billion billion different addresses
Colon hexadecimal notation:
◦ addresses are written using 32 hexadecimal digits.
◦ digits are arranged into 8 groups of four to improve the readability.
◦ Groups are separated by colons
2001:0718:1c01:0016:020d:56ff:fe77:52a3

Colon-Hex
◦ 3ffe:3600:2000:0800:0248:54ff:fe5c:8868
Compressed Format:
◦ 3ffe:0b00:0c18:0001:0000:0000:0000:0010
◦ becomes 3ffe:b00:c18:1::10

Unicast IPv6 Addresses
The following types of addresses are unicast IPv6 addresses:
◦ Global unicast addresses
◦ Link-local addresses
◦ Site-local addresses
◦ Unique local IPv6 unicast addresses
◦ Special addresses

Global Unicast Addresses
Equivalent to public IPv4 addresses.
Globally routable and reachable on the IPv6 portion of the Internet.
Unlike the current IPv4-based Internet, which is a mixture of both flat and hierarchical routing,
the IPv6-based Internet has been designed from its foundation to support efficient, hierarchical
addressing and routing.
The scope, the portion of the IPv6 internetwork over which the address is unique, of a global
unicast address is the entire IPv6 Internet.
Global scoped communication are identified by high-level 3 bits set to 001 (2000::/3)

Global Unicast Address
Each aggregatable global unicast IPv6 address has three parts:
Fixed portion set to 001 – The three high-order bits are set to 001. The address prefix for currently assigned global
addresses is 2000::/3.
Global Routing Prefix – Site Prefix
◦ Site prefix assigned to an organization (leaf site) by a provider should be at least a /48 prefix = 45 + high-order bits
(001).
◦ /48 prefix represents the high-order 48-bit of the network prefix.
◦ prefix assigned to the organization is part of the provider’s prefix.
Subnet-id - Site
◦ With one /48 prefix allocated to an organization by a provider, it is possible for that organization to enable up to
65,535 subnets (assignment of 64-bit’s prefix to subnets).
◦ The organization can use bits 49 to 64 (16-bit) of the prefix received for subnetting.
Interface-id – Host
◦ The host part uses each node’s interface identifier.
◦ This part of the IPv6 address, which represents the address’s low-order 64-bit, is called the interface ID.

Special IPv6 Addresses
The following are special IPv6 addresses:
Unspecified address
◦ unspecified address (0:0:0:0:0:0:0:0 or ::) is only used to indicate the absence of an address.
◦ equivalent to the IPv4 unspecified address of 0.0.0.0.
◦ used as a source address for packets attempting to verify the uniqueness of a tentative
address.
◦ never assigned to an interface or used as a destination address.
Loopback address
◦ The loopback address (0:0:0:0:0:0:0:1 or ::1) is used to identify a loopback interface, enabling
a node to send packets to itself.
◦ It is equivalent to the IPv4 loopback address of 127.0.0.1.
◦ Packets addressed to the loopback address must never be sent on a link or forwarded by an
IPv6 router.

Multicast Address
Main goal of multicasting is having an efficient network to save bandwidth
on links by optimizing the number of packets exchanged between nodes
In IPv4:
◦ 224.0.0.0/3, where the high-order 3-bit of the IPv4 address is set to 111
In IPv6:

Anycast Address
Anycast addresses can be considered a conceptual cross between unicast and multicast addressing.
◦ Unicast  send to this one address
◦ Multicast  send to every member of this group
◦ Anycast  send to any one member of this group
In choosing which member to send to, for efficiency reasons normally send to the closest one - closest
in routing terms.
So, anycast mean “send to the closest member of this group”.
The network itself plays the key role in anycast by routing the packet to the nearest destination by
measuring network distance.
Anycast addresses use aggregable global unicast addresses.
They can also use site-local or link-local addresses.
Note that it is impossible to distinguish an anycast address from a unicast address.

Reserved Anycast Address
Also called the subnet-router anycast address.
All IPv6 routers are required to support subnet-router anycast addresses for each of their subnet
interfaces.
Mobile IPv6 is an example of a protocol designed to use anycasting.

5 configuring TCP/IP

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