Defining Network Infrastructure

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Defining Network Infrastructure

A network can be defined as the grouping of hardware devices and software components which are necessary to connect

devices within the organization, and to connect the organization to other organizations and the Internet.

Typical hardware components utilized in a networking environment are network interface cards, computers,routers, hubs, switches, printers, and cabling and phone lines.

Typical software components utilized in a networking environment are the network services and protocols neededto enable devices to communicate.

Only after the hardware is installed and configured, can operating systems and software be installed into the network

infrastructure. The operating systems which you install on your computers are considered the main software components

within the network infrastructure. This is due to the operating system containing network communication protocols that

enable network communication to occur. The operating system also typically includes applications and services that

implement security for network communication.

Another concept, namely network infrastructure, is also commonly used to refer to the grouping of physical hardware and

logical components which are needed to provide a number of features for the network, including these common features: Connectivity Routing and switching capabilities Network security Access controlThe network or network infrastructure has to exist before a number of servers needed to support applications which are

needed by your users can be deployed into your networking environment:

File and print servers Web and messaging servers Database servers Application serversWhen youplan your network infrastructure, a number of key elements need to be clarified or determined:

Determine which physical hardware components are needed for the network infrastructure which you want toimplement.

Determine the software components needed for the network infrastructure. Determine the following important factors for your hardware and software components:

Specific location of these components How the components are to be installed. How the components are to be configured.

When you implement a network infrastructure, you need to perform a number of activities that can be broadly grouped as

follows:

Determine the hardware and software components needed. Purchase, assemble and install the hardware components. Install and configure the operating systems, applications and all other software.


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Thephysical infrastructure of the network refers to the physical design of the network together with the hardware

components. The physical design of the network is also called the networkstopology. When you plan the physical

infrastructure of the network, you are usually limited in your hardware component selection by the logical infrastructure of

the network

The logical infrastructure of the networkis made up of all the software components required to enable connectivity between

devices, and to provide network security. The networks logical infrastructure consists of the following: Software products Networking protocols/services.It is therefore the networks logical infrastructure that makes it possible for computers to communicate using the routes

defined in the physical network topology.

The logical components of the network topology define a number of important elements:

Speed of the network. Type of switching that occurs. Media which will be utilized. Type of connections which can be formed.Understanding the OSI Reference Model and TCP/IP Protocol Suite

The International Organization for Standardization (ISO) developed the Open Systems Interconnection (OSI) reference

model for computing. TheOSI modeldefines how hardware and software function to enable communication between

computers. The OSI model is a conceptual framework which can be referenced to better comprehend how devices operate on

the network. It is the most widely used guide for a networking infrastructure. When manufacturers design new products, they

reference the OSI models concepts on the manner in which hardware and software components should function.

The OSI model defines standards for:

How devices communicate between each other. The means used to inform devices when to send data and when not to transmit data. The methods which ensure that devices have a correct data flow rate. The means used to ensure that data is passed to, and received by the intended recipient. How physical transmission media is arranged and connected.The OSI model is made up of seven layers which are presented as a stack. Data which is passed over the network moves

through each layer. Each layer of the OSI model has its own unique functions and protocols. Different protocols operate at

the different layers of the OSI model. The layer of the OSI reference model at which the protocol operates defines itsfunction. Different protocols can operate together at different layers within a protocol stack. When protocols operate

together, they are referred to as aprotocol suite or protocol stack.When protocols support multiple path LAN-to-LAN

communications, they are called routable protocols. The binding order determines the order in which the operating system

runs the protocols.

The seven layers of the OSI reference model, and each layers associated function are listed here:

Physical Layer layer 1: The Physical layer transmits raw bit streams over a physical medium, and deals withestablishing a physical connection between computers to enable communication. The physical layer is hardware

specific; it deals with the actual physical connection between the computer and the network medium. The medium

used is typically a copper cable that utilizes electric currents for signaling. Other media that are becoming popular

are fiber-optic and wireless media. The specifications of the Physical layer include physical layout of the network,

voltage changes and the timing of voltage changes, data rates, maximum transmission distances, and physical

connectors to transmission mediums. The issues normally clarified at the Physical Layer include:
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Whether data is transmitted synchronously or asynchronously. Whether the analog or digital signaling method is used. Whether baseband or broadband signalling is used.

Data-Link Layer layer 2: The Data-link layer of the OSI model enables the movement of data over a link fromone device to another, by defining the interface between the network medium and the software on the computer.

The Data-link layer maintains the data link between two computers to enable communications. The functions of

the Data-link layer include packet addressing, media access control, formatting of the frame used to encapsulate

data, error notification on the Physical layer, and management of error messaging specific to the delivery of

packets. The Data-link layer is divided into the following two sublayers:

TheLogical Link Control (LLC) sublayerprovides and maintains the logical links used forcommunication between the devices.

TheMedia Access Control (MAC) sublayercontrols the transmission of packets from one networkinterface card (NIC) to another over a shared media channel. A NIC has a unique MAC address, or

physical address. The MAC sublayer handles media access control which essentially prevents data

collisions. The common media access control methods are:

Token Passing; utlized in Token Ring and FDDI networks Carrier Sense Multiple Access/Collision Detection (CSMA/CD); utilized inEthernetnetworks. Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA);utilized in AppleTalk

networks.

Network Layer layer 3: The Network layer provides end-to-end communications between computers that existon different network. One of the main functions performed at the Network layer is routing. Routing enables

packets to be moved between computers which are more than one link from one another. Other functions include

traffic direction to the end destination, addressing, packet switching and packet sequence control, end-to-end error

detection, congestion control, and Network layer flow control and error control.

Transport Layer layer 4: The Transport layer deals with transporting data in a sequential manner, and with nodata loss. The Transport layer divides large messages into smaller data packets so that it can be transmitted to the

destination computer. It also reassembles packets into messages for it to be presented to the Network layer.

Functions of the Transport layer include guaranteed data delivery, name resolution, flow control, and error

detection and recovery. The common Transport protocols utilized at this layer are Transmission Control Protocol

(TCP)and User Datagram Protocol (UDP).

Session Layer layer 5: The Session layer enables communication sessions to be established between processes orapplications running on two different computers. A process is a specific task that is associated with a particular

application. Applications can simultaneously run numerous processes. The Session layer establishes, maintains and

terminates communication sessions between applications. The Session layer utilizes the virtual circuits created by

the Transport layer to establish communication sessions.

Presentation Layer layer 6: The Presentation layer is responsible for translating data between the formats whichthe network requires and the formats which the computer is anticipating. The presentation layer translates the

formats of each computer to a common transfer format which can be interpreted by each computer. Functions

include protocol conversion, data translation, data encryption and decryption, data compression, character set

conversion, and interpretation of graphics commands.

Application Layer layer 7: The Application layer provides the interface between the network protocol and thesoftware running on the computer. It provides the interface for e-mail, Telnet and File Transfer Protocol (FTP)

applications, and files transfers. This is the location where applications interrelate with the network.

Transmission Control Protocol/Internet Protocol (TCP/IP) is a network communication protocol suite that can be utilized as

the communications protocol on private networks. TCP/IP is also the default protocol utilized on the Internet. The majority

of network infrastructures are based on TCP/IP.

As an engineer designing the network infrastructure, you have to provide a TCP/IP design which can provide the following:
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Connect devices in the private internal network to the Internet. Enable users to access TCP/IP based resources. Protect confidential company data. Provide application responses in accordance to the requirements of the organization.The TCP/IP protocol suite is a four layer model which corresponds to seven layers of the OSI reference model:

Network Interface layer: The Network Interface layer maps to the Physical Layer (Layer 1) and the Data-link layer(Layer 2) of the OSI reference model. The Network Interfae layers function is to move bits (0s and 1s) over the

network medium.

Internet layer: The Internet layer is associated with the OSI models Network layer. The Internet layer handles thepackaging, addressing, and routing of data. The main protocols of the TCP/IP suite that operate at the Internet

layer are:

Internet Protocol (IP): IP is a connectionless, routable protocol which performs addressing and routingfunctions. IP places data into packets, and removes data from packets.

Internet Control Message Protocol (ICMP): The protocol is responsible for dealing with errorsassociated with undeliverable IP packets, and for indicating network congestion and timeout conditions.

Internet Group Management Protocol (IGMP): The IGMP protocol controls host membership in groupsof devices, called IP multicast groups. The devices in the IP multicast groups receive traffic which is

addressed to a shared multicast IP address. Unicast messages are sent to a host, while a multicast is sent

to each member of an IP multicast group.

Address Resolution Protocol (ARP): The ARP protocol maintains the associations which map IPaddresses to MAC addresses. Because mappings are stored in theARP Cache,when the same IP address

needs to be mapped again to its associated MAC address, the discovery process is not performed again.

Reverse Address Resolution (RARP) resolves MAC addresses to IP addresses.

Transport layer/ Host-to-Host Transport: This layer is associated with the Transport layer of the OSI model. Themain TCP/IP protocols operating at the Host to Host or Transport layer are: Transmission Control Protocol (TCP): TCP offers greater reliability when it comes to transporting data

than what UDP, the other protocol which works at this level provides. With TCP, the application which

sends the data receives acknowledgement or verification that the data was actually received. TCP is

regarded as a connection-orientated protocola connection is established before data is transmitted. A

three-part TCP handshake process is performed to establish a host to host connection. The three-part

TCP handshake process establishes a reliable connection over which to exchange data.

User Datagram Protocol (UDP):UDP does not provide reliable data transport. No acknowledgementsare transmitted. While UDP is faster than TCP, it is less reliable.

Application layer: The Application layer is associated with the Session layer, Presentation layer, and Applicationlayer of the OSI model. Application layer protocols of the TCP/IP protocol suite functions at these layers.

Application layer protocols enable applications to communicate between each other, and also provide access to theservices of the lower layers.

Understanding Networking Services

Running on the physical hardware in the network infrastructure are networking services. Networking services basically

extend the physical network by providing a number of key capabilities, including the following:

Multiprotocol support,networks can run multiple protocol, including: Transmission ControlProtocol/Internet Protocol (TCP/IP) Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) Appletalk
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Systems Network Architecture (SNA) Multiprotocol routing among network different network segments: The Routing and Remote Access Service

(RRAS) feature of Windows 2000 and Windows Server 2003 can be used to identify networks with different

topologies and secure segments of the network. The Routing and Remote Access Service can be configured for:

LAN-to-LAN routing

LAN-to-WAN routing Virtual private network (VPN) routing Network Address Translation (NAT)routing Routing features, including IP multicasting, Packet filtering, Demand-dial routing, and DHCP relay

Support for strong network security: Internet Protocol Security (IPSec) and Virtual Private Networks (VPNs) canbe used to provide a number of features. VPNs provide secure and advanced connections through a non-secure

network by providing data privacy. Private data is secure in a public environment. VPN client software is assured

private access in a publicly shared environment. By using analog, ISDN, DSL, cable technology, dial and mobile

IP; VPNs are implemented over extensively shared infrastructures. IPSec protects, secures and authenticates databetween IPSec peer devices by providing per packet data authentication. Data flows between IPSec peers are

confidential and protected. IPSec supports the following:

Unicast IP datagrams High-Level Data-Link Control (HDLC) ATM Point-to-Point Protocol (PPP) Frame Relay serial encapsulation Generic Routing Encapsulation (GRE) IP-in-IP (IPinIP) Encapsulation Layer 3 tunneling protocols.

Enable connectivity between the private internal network and Internet applications:Networking services such asthe RRAS service and Network Address Translation (NAT)service enable users on the private internal network to

connect to the Internet, while at the same time securingresourceslocated on the private network.

NAT translates IP addresses and associated TCP/UDP port numbers on the private network to public IPaddresses which can be routed on the Internet. Through NAT, host computers are able to share a single

publicly registered IP address to access the Internet. NAT also offers a number of security features which

can be used to secure the resources on your private network.

RRAS IP packet filters can be used to restrict incoming or outgoing IP address ranges based oninformation in the IP header. You can configure and combine multiple filters to control network traffic.

You can also map external public IP addresses and ports to private IP addresses and ports so that internal

private resources can be accessed by Internet users. You use a special port to map specific Internet users

to resources within the private network.

The Internet Connection Sharing (ICS) service is basically a simplified implementation of a NetworkAddress Translation (NAT)server. You can use ICS to connect the entire network to the Internet. This is

due to the ICS service providing a translated connectionall computers can access resources on the

Internet. Implementing ICS is though only recommended for those exceptionally small networks.

Microsoft Proxy Server can also be used to provide connectivity between the private internal network,and Internet applications.
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Enable users to remotely access the private network.The service that enables this capability is the Routing andRemote Access Service (RRAS). The different types of remote access are:

Dial-in remote access: Dial-in remote access uses modems and servers running the Routing and RemoteAccess (RRAS) service. To enable communication, dial-in access utilizes the Point-to-Point (PPP)

protocol.

VPN remote access: A VPN provides secure and advanced connections through a non-secure network.With VPN access, encryption is used to create the VPN tunnel between the remote client and the

corporate network. To secure VPN access, Windows Server 2003 provides strong levels of encryption.

Wireless remote access: Wireless networks are defined by the IEEE 802.11 specification. With wirelessnetworks, wireless users connect to the network through connecting to a wireless access point (WAP).

To secure wireless networks and wireless connections, administrators can require all wireless

communications to be authenticated and encrypted. When planning wireless remote access, planning

security for wireless networks should be a high priority factor.

Name resolution capabilities: The Domain Name System (DNS)service or Windows Internet Name Service(WINS)service can be used to resolve host names to IP addresses. Name resolution has to occur whenever the host

name is used to connect to a computer and not the IP addresses. Name resolution has to occur so that the IP

address can be resolved to the hardware address for TCP/IP based communication to occur. The DNS service resolves host names and fully qualified domain names (FQDNs) to IP addresses in

TCP/IP based networks. The DNS server manages a database of host name to IP address mappings. This

is the primary method used for name resolution in Windows Server 2003.

WINS is an enhanced NetBIOS name server (NBNS) which was designed by Microsoft to resolveNetBIOS computer names to IP addresses, and at the same time eliminate the usage ofbroadcastsfor

name resolution. WINS can resolve NetBIOS names for local hosts and remote hosts.

Automatic configuration of IP addressing and other IP parameters: The Dynamic Host Configuration Protocol(DHCP)service simplifies the administration of IP addressing in TCP/IP based networks. One of the primary tasks

of the protocol is to automatically assign IP addresses to DHCP clients. A server running the DHCP service is

called a DHCP server. The DHCP protocol automates the configuration of TCP/IP clients because IP addressing

occurs through the system. IP addresses that are assigned via a DHCP server are regarded as dynamically assigned

IP addresses. The DHCP server assigns IP addresses from a predetermined IP address range(s). The functions of

the DHCP server running the DHCP service are listed here:

Dynamically assign IP addresses to DHCP clients. Assign the following TCP/IP configuration information to DHCP clients:

Subnet mask information Default gateway IP addresses Domain Name System (DNS) IP addresses. Windows Internet Naming Service (WINS)IP addresses.

There are a number of tools and features included with Windows 2000 and Windows Server 2003 that can be used to

manage and monitor the networking services which you deploy within your networking infrastructure.

Network Infrastructure Planning Overview

Planning network infrastructure is a complex task that needs to be performed so that the network infrastructure needed by the

organization can be designed and created. Proper planning is crucial to ensure a highly available network

andhigh performancenetwork that result in reduced costs and enhances business procedures for the organization.

To properly plan your network infrastructure, you have to be knowledgeable on a number of factors, including the following:

Requirements of the organization. Requirements of users.
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The Resultant Set of Policy (RSoP) MMC snap-in can be used to determine the effects of applying changes toGroup Policy Objects (GPOs) in Windows 2000 and Windows Server 2003 Active Directory

environments beforeapplying the changes.

The Group Policy Management Console (GPMC) can be used if you want to view configuration information onthe existing GPO settings in Windows 2000 and Windows Server 2003 Active Directory environments.

Determining Network Layer and Transport Layer Protocols

Windows Server 2003 supports the following network layer and transport layer protocol combinations:

Transmission Control Protocol/Internet Protocol (TCP/IP): TCP/IP is a grouping of protocols which provides acollection of networking services. TCP/IP is the main protocol which Windows Server 2003 utilizes for its

network services. The main protocols in the TCP/IP suite are Transmission Control Protocol (TCP)that operates

at the Transport layer, andInternet Protocol (IP)that operates at the Network layer. When communication takes

place through TCP/IP, IP is used at the Network layer, and either TCP or UDP is used at the Transport layer. With

TCP/IP, the TCP component of the protocol suite utilizesport numbers to forward messages to the correct

application process. Port numbers are assigned by the Internet Assigned Numbers Authority (IANA), and they

identify the process to which a particular packet is connected to. Port numbers are found in the packet header.

The main advantages of using TCP/IP are summarized below:

Can be used to establish connections between different types of computers and servers. Includes support for a number of routing protocols. Enables internetworking between organizations. Includes support for name and address resolution services, including Domain Name Service (DNS),

Dynamic Host Configuration Protocol (DHCP), and Windows Internet Name Service (WINS).

Includes support for a number of different Internet standard protocols for Web browsing, file and printservices, and transporting mail.

The disadvantages of TCP/IP are summarized below:

IPX is faster than TCP/IP. TCP/IP is intricate to set up and manage. The overhead of TCP/IP is higher than that of IPX.

Internetwork Packet Exchange (IPX): The Microsoft implementation of Novells IPX/SPX protocol stack isNWLink IPX/SPX. NWLink IPX/SPX is used in Novell NetWare, and is basically IPX for Windows. Windows

Server 2003 includes NWLink IPX/SPX support to enable Windows Server 2003 to communicate with legacy

Novell NetWare servers and clients. NWLink IPX/SPX could become problematic in large networks because it

does not have a central IPX addressing scheme which prevents networks from utilizing the same address numbers.

The main advantages of NWLink IPX/SPX are summarized below:

NWLink IPX/SPX is simple to implement and manage. Connecting to is NetWare servers and clients is a simple process. NWLink IPX/SPX is routableThe disadvantages of NWLink IPX/SPX are summarized below:

Windows Server 2003 only includes limited support for NWLink IPX/SPX. Exchanging data between different organizations via NWLink IPX/SPX is an intricate process. NWLink IPX/SPX does not support standard network management protocols.
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NetBIOS Extended User Interface (NetBEUI):NetBIOS naming is supported in Windows Server 2003. WindowsServer 2003 does not though support the NetBEUI protocol. NetBEUI is a single protocol that was initially used in

Windows NT 3.1 and Windows for Workgroups operating systems. The protocol provides basic file sharing

services for Windows computers, and is designed for small networks. NetBEUI does not perform well on large

networks. The protocol can also not support internetwork traffic because it cannot route traffic between networks.

NetBEUI cannot address traffic to a computer on a different network

TCP/IP Design Requirements

Before deciding to use a TCP/IP based network design, you first have to determine whether you actually need to utilize

TCP/IP. Whether a TCP/IP based network design is required or not is dictated by the networking services and applications

required within your network infrastructure:

TheActive Directory directory service uses the Lightweight Directory Access Protocol (LDAP) and DomainName System (DNS). These protocols are dependent on TCP/IP.

Domain Name System (DNS) is the primary name resolution method used in Windows Server 2003, and isdependent on TCP/IP being installed.

Web servers usethe File Transfer Protocol (FTP)protocol and HTTP protocol, which are each reliant on TCP/IP. As mentioned earlier, the default protocol on the Internet is TCP/IP. In fact, all Internet protocols are based on

TCP/IP. If you are planning to enable internet connectivity, TCP/IP is a requirement.

BothLine Printer Daemon (LPD) and PrinterRemote (LPR) printers need TCP/IP to be installed. To enable interoperability between UNIX and other operating systems, TCP/IP is used as the common transport

protocol.

In order to implement a TCP/IP network infrastructure, you have to gather a number of design requirements, including the

following:

The existing TCP/IP networks characteristics, if applicable, should include: The number of network segments which currently exist. The IP address range assigned to the organization. The routing protocols being utilized.

The attributes of the data which is to be transmitted over the network segments: The quantity of data transmitted over each network segment. The confidentiality requirements of the data.

The amount of tie which users need to access the network. The desired response times for any applications that access resources in the network. Possible future network expansion expectations.There are a number of additional factors which need to be determined before you can create a routing solution for your

network:

The IP addressing scheme which will be utilized. The IP subnet masks which will be utilized. The Variable Length Subnet Masks (VLSMs) which will be utilized. The Classless Interdomain Routing utilization. The standards for creating TCP/IP filters
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The authentication methods for protecting access to the private network. The encryption algorithms for ensuring data confidentiality.Determining the IP Addressing Scheme

The IP addressing scheme which you use can be based on:

Public IP addresses: Here, the IP addressing scheme consists of only public IP addresses. Private IP addresses: Here, the IP addressing scheme consists of private IP addresses and a small number of public

IP addresses needed to enable Internet connectivity.

If you are only using apublic IP addressing scheme in your network design, then you need to perform the following

activities:

Purchase a range of public IP addresses from an ISP that is approved by the Internet Corporation for AssignedNames and Numbers (ICANN).

The IP address range should have sufficient IP addresses for all interfaces in your network infrastructure design.Devices that connect to the private network need an IP address, and so too does VPN connections.

You need to be certain that network address translation (NAT)is not required. You need to implementfirewallsand router packet filters to secure the resources within your private network from

Internet users.

If you are implementing aprivate IP addressing scheme, then the network design would consist of the following:

Private IP addresses would be assigned to all devices in the private internal network. Public IP addresses would be assigned to all devices connecting to the public network.The selection of the IP address range needed for the organization should be based on the following factors:

Maximum number of IP devices on each subnet

Maximum number of network subnets needed in the network design.If you are using a private IP addressing scheme in your network design, consider the following important points:

For those IP devices that connect the company network to public networks such as the Internet, you need to obtaina range of public IP addresses from the ISP for these devices.

You should only assign public IP addresses to those devices that communicate directly with the Internet. This ismainly due to you paying for each IP address obtained. Devices which directly connect to the Internet are your

network address translation (NAT)servers, Web servers, VPN remote access servers, routers, firewalldevices, and

Internet application servers.

The private IP address range which you choose should have sufficient addresses to support the number of networksubnets in your design, and the number of devices or hosts on each particular network subnet.

You must cater for a network address translation (NAT)implementation. NAT translates IP addresses andassociated TCP/UDP port numbers on the private network to public IP addresses which can be routed on the

Internet. Networks that do not require an implementation of a firewall solution or a proxyserver solutioncan use

NAT to provide basic Internet connectivity. Through NAT, host computers are able to share a single publicly

registered IP address to access the Internet.

IP version 6 (IPv6) was designed to deal with the current shortage of IP addresses with IP version 4 (IPv4). IP version 6

also includes some modifications to TCP/IP.

The primary differences between IPv6 and IPv4 are listed here

Source and destination addresses:IPv4: 128 bits in length; IPv6: 32 bits in length IPSec support: IPv4: Optional; IPv6: Required.
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Configuration of IP addresses: IPv4: Manually or via DHCP; IPv6: Via Address Autoconfiguration - DHCP is nolonger required, nor is manual configuration.

Packet flow identification for QoS handling in the header: IPv4: No identification of packet flow; IPv6: Packetflow identification for QoS handling exists via the Flow Label field.

Broadcast addresses:IPv4: Broadcast addresses are used to transmit traffic to all nodes on a specific subnet; IPv6:Broadcast addresses are replaced by a link-local scope all-nodes multicast address.

Fragmentation: IPv4: Performed by the sending host and at the routers; IPv6: Performed by the sending host. Reassembly: IPv4: Has to be able to reassemble a 576-byte packet; IPv6: Has to be able to reassemble a 1,500-byte

packet.

ARP Request frames:IPv4: Used by ARP to resolve an IPv4 address to a link-layer address; IPv6: Replaced withNeighbor Solicitation messages.

ICMP Router Discovery: IPv4: Used to determine the IPv4 address of the optimal default gateway; IPv6: Replacedwith ICMPv6 Router Solicitation and Router Advertisement messages.

Internet Group Management Protocol (IGMP): IPv4: Used to manage local subnet group membership; IPv6:Replaced with Multicast Listener Discovery (MLD) messages.

Header checksum: IPv4: Included; IPv6: ExcludedThe advantages of IPv6 are listed below:

Large address space:Because of the larger number of available addresses, it is no longer necessary to use utilizeNetwork Address Translator (NAT)to map a public IP address to multiple private IP addresses.

A new header format which offers less overhead: The new header format of IPv6 is designed to minimize headeroverhead. All optional fields which are needed for routing are moved to extension headers. These extension

headers are located after the IPv6 header. The IPv6 header format is also streamlined so that it is more efficiently

processed at intermediate routers. The number of bits in IPv6 addresses is four times larger than IPv4 addresses.

An efficient hierarchical addressing and routing infrastructure:The IPv6 global addresses are designed to createan efficient routing infrastructure.

Built in support for securityIPSec: A requirement of IPv6 is support for IPSec. IPSec contains the followingcomponents that provide security:

Authentication header (AH): The AH provides data authentication, data integrity and replay protectionfor the IPv6 packet. The only fields in the IPv6 packet that are excluded are those fields that change

when the packet moves over the network.

Encapsulating Security Payload (ESP) header: The ESP header provides data authentication, dataconfidentiality, data integrity, and replay protection for ESP encapsulated payload

Internet Key Exchange (IKE) protocol: The IKE protocol is used to negotiate IPSec security settings. Support for Stateless and stateful address configuration: IPv6 can support a stateful address configuration and a

stateless address configuration. With IPv4, hosts configured to use DHCP have to wait a minute before they can

configure their own IPv4 addresses. Stateless address configuration however enables a host on a link to

automatically configure its own IPv6 address for the link. These addresses are called link-local addresses. A link-

local address is configured automatically, even when no router exists. This allows communication between

neighboring nodes on the same link to occur immediately.

Support for Quality of service (QoS)header fields: There are new fields in the IPv6 header that specify the waytraffic is identified and handled.

Traffic Class field:This field defines traffic that must be prioritized. Flow Label field:This field enables the router to identify packets, and also handle packets that are part of

the identical flow in a special way.

Unlimited extension headers: You can add extension headers after the IPv6 header if you want to extend IPv6 forany new features.

The Neighbor Discovery (ND) protocol for managing nodes on the same link:Neighbor Discovery is a series ofInternet Control Message Protocol for IPv6 (ICMPv6) messages that are used in IPv6 environments to identify the

relationships between neighboring nodes. ND enables hosts to discover routes on the same segment, addresses and

address prefixes. Address Resolution Protocol (ARP), ICMPv4 Router Discovery and ICMPv4 Redirect messages

are replaced with the more efficient multicast and unicast Neighbor Discovery messages.
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If you want an IP address to provide all services to the network, then each particular service must have a unique TCP port or

UDP port from that specific IP address. There are a number of well-known portswhich are used by the different services

running on your computers.

Documents

Defining Network Infrastructure