2.3 Explain the properties and characteristics of TCP/IP 14
Here are a few terms used in the IPv6 standards:
-- A link, sometimes called the local link, or local network, is a local area network (LAN) or wide area network (WAN) bounded by routers. -- A node is any device that connects to the network, such as a computer, printer, or router. An interface is a node's attachment to a link. The attachment can be a logical attachment, such as when a virtual machine connects to the network, or a physical attachment, such as when a network adapter connects to the wired network. -- The last 64 bits or 4 blocks of an IP address identify the interface and are called the Interface ID or interface identifier. These 64 bits uniquely identify an interface on the local network. -- Neighbors are nodes on the same local network.
IPv6 supports these three types of IP addresses: -- A unicast address is used to send messages to a single node on a network. Three types of unicast addresses are link-local addresses, unique local addresses, and global addresses.
-- A multicast address is used to deliver messages to all nodes in a targeted, multicast group, such as when video is streaming from a server to multiple nodes on a network. 14 -- An anycast address is used by routers and can identify multiple destinations and a message is delivered only to the closest destination
The Subnet Mask identifies which part of an IP address is the network portion and which part is the host portion.
A computer or other device can use its subnet mask to know if an IP address of another computer is on its network or another network
Today we need many more than four billion IP addresses over the world. Partly because of a shortage of 32-bit IP addresses, Internet Protocol version 6 (IPv6), which uses an IP address with 128 bits, was developed.
Currently, the Internet uses a mix of 32-bit and 128-bit IP addresses. The Internet Assigned Numbers Authority (IANA at iana.org) is responsible for keeping track of assigned IP addresses and has already released all its available 32-bit IP addresses. IP addresses leased from IANA today are all 128-bit addresses.
A 32-bit IP address is organized into four groups of 8 bits each, which are presented as four decimal numbers separated by periods, such as 72.56.105.12. The largest possible 8-bit number is 11111111, which is equal to 255 in decimal, so the largest possible IP address in decimal is 255.255.255.255, which in binary is 11111111.11111111.11111111.11111111.
Each of the four numbers separated by periods is called an OCTET for 8 bits) and can be any number from 0 to 255, making a total of about 4.3 billion IP addresses (256 × 256 × 256 × 256). Some IP addresses are reserved, so these numbers are approximations.
IP addresses available to the Internet are called public IP addresses. To conserve the number of public IP addresses, some blocks of IP addresses have been designated as private IP addresses that are not allowed on the Internet. Private IP addresses are used within a company's private network, and computers on this network can communicate with one another using these private IP addresses.
IEEE recommends that the following IP addresses be used for private networks: -- 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
Ip address: 255.255.255.255 how It Is Used: Used for broadcast messages by tCp/Ip background processes
Ip address: 0.0.0.0 Currently unassigned Ip address Ip address: 127.0.0.1 how It Is Used: Indicates your own computer and is called the loopback address
A computer or other device (such as a network printer) that requests an address from a DHCP server is called a DHCP Client.
It is said that the client is leasing an IP address.
When your computer at home is connected to your Internet service provider (ISP) off somewhere in the distance, your computer and a computer on the Internet must be able to communicate.
When two devices communicate, they must use the same protocols so that the communication makes sense. For almost all networks today, including the Internet, the group or suite of protocols used is called TCP/IP (Transmission Control Protocol/ Internet Protocol).
For dynamic IP addresses,
a DHCP (Dynamic Host Configuration Protocol) server gives an IP address to a computer when it first attempts to initiate a connection to the network and requests an IP address.
A unique local address
a private address that can travel across subnets within the private network. These addresses are used by network administrators when subnetting a large network.
An IP address has 32 bits or 128 bits. When the Internet and TCP/IP were first invented, it seemed that 32 bits were more than enough to satisfy any needs we might have for IP addresses because this standard,
called Internet Protocol version 4 (IPv4), created about four billion potential IP addresses.
A global unicast address, also called a global address,
can be routed on the Internet. These addresses are similar to IPv4 public IP addresses. The first 48 bits of the address is the Global Routing Prefix. When an ISP assigns a global address to a customer, it's these 48 bits that it assigns. An organization that leases one Global Routing Prefix from its ISP can use it to generate many IPv6 global addresses.
A link-local unicast address, also called a link-local address or local address,
can be used for communicating with neighboring nodes in the same link (the local network). These local addresses are similar to IPv4 private IP addresses and most begin with FE80::/64.
If a computer first connects to the network that is using dynamic IP addressing and is unable to lease an IP address from the DHCP server,
it generates its own Automatic Private IP Address (APIPA) in the address range 169.254.x.y.
A DHCP Server
that serves up IPv6 addresses is often called a DHCPv6 server.
In Windows,
the ipconfig command can be used to show the IP addresses assigned to all network connections.
NAT (Network Address Translation) is a technique designed to conserve the number of public IP addresses needed by a network.
A router or other gateway device stands between a private network and the Internet and substitutes the private IP addresses used by computers on the private network with its own public IP address when these computers need access to the Internet.
The first part of an IP address identifies the network, and the last part identifies the host. When messages are routed over the Internet, the network portion of the IP address is used to locate the right local network
After the message arrives at the local network, the host portion of the IP address is used to identify the one computer on the network that is to receive the message.
Using the IPv6 standards, more has changed than just the number of bits in an IP address. To improve routing capabilities and speed of communication, IPv6 changed the way IP addresses are used to find computers on the Internet.
Let's begin our discussion of IPv6 by looking at how IPv6 addresses are written and displayed: -- An IPv6 address has 128 bits that are written as eight blocks of hexadecimal numbers separated by colons, like this: 2001:0000:0B80:0000:0000:00D3:9C5A:00CC. -- Each block is 16 bits. For example, the first block in the address above is 2001 in hex, which can be written as 0010 0000 0000 0001 in binary. -- Leading zeros in a four-character hex block can be eliminated. For example, the IP address above can be written as 2001:0000:B80:0000:0000:D3:9C5A:CC. -- If blocks contain all zeros, they can be written as double colons (::). The IP address above can be written two ways: 2001::B80:0000:0000:D3:9C5A:CC 2001:0000:B80::D3:9C5A:CC
Level 1: Hardware level. At the root level of communication is hardware. The hardware or physical connection might be wireless or might use network cables, phone lines (for DSL or dial-up), or TV cable lines (for a cable modem). For local wired or wireless networks, a network adapter (also called a network card, a network interface card, or a NIC) inside your computer is part of this physical network. Every network adapter (including a network card, network port on a motherboard, onboard wireless, or wireless NIC) has a 48-bit (6-byte) number hard-coded on the card by its manufacturer that is unique for that device (see Figure 14-3). The number is written in hexadecimal, and is called the MAC (Media Access Control) address, hardware address, physical address, adapter address, or Ethernet address. Part of the MAC address identifies the manufacturer that is responsible for making sure that no two network adapters have the same MAC address. MAC addresses are used to locate a computer on a local area network (LAN). A local area network (LAN) is a network bound by routers or other gateway devices. A router is a device that manages traffic between two or more networks and can help find the best path for traffic to get from one network to another. A gateway is any device or computer that network traffic can use to leave one network and go to a different networ
Level 2: Operating system level. Operating systems use IP addresses to find other computers on a network. An IP address is a 32-bit or 128-bit string that is assigned to a network connection when the connection is first made. Whereas a MAC address is only used to find a computer on a local network, an IP address can be used to find a computer anywhere on the Internet (see Figure 14-4) or on an intranet. An intranet is any private network that uses TCP/IP protocols. A large enterprise might support an intranet that is made up of several local networks. A local network can further be divided into smaller networks and each of these smaller networks is called a subnetwork or subnet. IP addresses are used to find computers on subnets, an intranet, or the Internet Level 3: Application level. Most applications used on the Internet or a local network are client/server applications. Client applications, such as Internet Explorer, Google Chrome, or Outlook, communicate with server applications such as a web server or email server. Each client and server application installed on a computer listens at a predetermined address that uniquely identifies the application on the computer. This address is a number and is called a port number, port, or port address. For example, you can address a web server by entering into a browser address box an IP address followed by a colon and then 80, which is the port number for a web server application. Suppose a computer with an IP address of 136.60.30.5 is running both an email server, which listens at port 25, and a web server application listening at port 80. If a client computer sends a request to 136.60.30.5:25, the email server that is listening at that port responds. On the other hand, if a request is sent to 136.60.30.5:80, the web server listening at port 80 responds (see Figure 14-5
A computer making a request from another is called the client and the one answering the request is called the server.
Most communication between computers on a network or the Internet uses this Client/Server model. For example, in Figure 14-1, someone uses a web browser on a client to request a webpage from a web server. To handle this request, the client computer must first find the web server, the protocols for communication are established, and then the request is made and answered. Hardware, the OS, and the applications on both computers are all involved in this process.
A MAC address is embedded on a network adapter at the factory, but IP addresses are assigned manually or by software. R
Recall that an IP address can be a Dynamic IP address (IP address is assigned by a server each time the computer or device connects to the network) or a Static IP address (IP address is permanently assigned to the computer or device).
subnet mask has 32 bits and is a string of 1s followed by a string of 0s, for example, 11111111.1111 1111.11110000.00000000. The 1s in a subnet mask say, "On our network, this part of an IP address is the network part," and the group of 0s says, "On our network, this part of an IP address is the host part." On Windows screens, a subnet mask is displayed in decimal, for example the subnet mask of 11111111.11111 111.00000000.00000000 is 255.255.0.0 in decimal
Suppose the IP address of a computer on Network A is 201.18.20.160 and the subnet mask is 11111111 .11111111.00000000.00000000. The subnet mask tells Windows that the first 16 bits or two octets of the IP address is the network ID. Therefore, when Windows is deciding how to communicate with a computer that has an IP address of 201.18.20.208, it knows the computer is on its own network, but a computer with an IP address of 201.19.23.160 is on another network.
IPv6 uses subnetting but doesn't need a subnet mask because the subnet ID that identifies a subnet is part of the IPv6 address.
The Subnet ID is the 16 bits following the first 48 bits of the address.
When two computers communicate using a local network or the Internet, communication happens at three levels (hardware, operating system, and application).
The first step in communication is one computer must find the other computer. The second step is both computers must agree on the methods and rules for communication (called Protocols). Then one computer takes on the role of making requests from the other computer.
Sometimes an IP address and subnet mask are written using a shorthand notation like 15.50.212.59/20, where the /20 means that the first 20 bits in the IP address identify the network.
This notation is sometimes called slash notation or CIDR notation (pronounced "cider notation"), named after the CIDR (Classless Interdomain Routing) standards that were written in 1993 about subnetting.
