1.3 Explain the purpose and properties of IP addressing.

IPv4 Address Class A

A Class A address uses only the first octet to represent the network portion 1 to 126 126 Networks 16,777,214 hosts 0xxxxxxx binary representation in the first octive Subnet 255.0.0.0 Private range 10.x.x.x 127.0.0.1 is used for loop back address

IPv4 address

An IPv4 address is composed of four sets of 8 binary bits, which are called octets. The result is that IP addresses contain 32 bits. Each bit in each octet is assigned a decimal value. The leftmost bit has a value of 128, followed by 64, 32, 16, 8, 4, 2, and 1, left to right. Each bit in the octet can be either a 1 or a 0. By using the set of 8 bits and manipulating the 1s and 0s, you can obtain any value between 0 and 255 for each octet.

Anycast Addresses

Anycast addresses represent the middle ground between unicast addresses and multicast addresses. Anycast delivers messages to any one node in the multicast group.

APIPA

Automatic Private IP Addressing (APIPA) 169.254.x.x address range. The function of APIPA is that a system can give itself an IP address if it is incapable of receiving an address dynamically from a DHCP server. Then APIPA assigns the system an address from the 169.254.0.0 address range and configures an appropriate subnet mask (255.255.0.0). However, it doesn't configure the system with a default gateway address. As a result, communication is limited to the local network. If a system that does not support APIPA cannot get an address from a DHCP server, it typically assigns itself an IP address of 0.0.0.0. Keep this in mind when troubleshooting IP addressing problems on non-APIPA platforms.

IPv4 address Class D

Class D is reserved for multicast addressing 224 to 239.x.x.x 1110xxxx binary representation in the first octet

IPv4 address Class E

Class E is reserved for future development 240 to 255.x.x.x 1111xxxx binary representation in the first octet

IPv6 address Types

Global Unicast Addresses Link-Local Addresses Site-Local Addresses

Global Unicast Addresses

Global unicast addresses are the equivalent of IPv4 public addresses. These addresses are routable and travel throughout the network.

Subnetting

Subnetting is a process by which the node portions of an IP address create more networks than you would have if you used the default subnet mask. It enables you to more effectively use IP address ranges. It makes IP networking more secure and manageable by providing a mechanism to create multiple networks rather than having just one. Using multiple networks confines traffic to the network that it needs to be on, which reduces overall network traffic levels. Multiple subnets also create more broadcast domains, which in turn reduces networkwide broadcast traffic. A difference exists between broadcast domains and collision domains: The latter is all the connected nodes, whereas the former is all the logical nodes that can reach each other. As such, collision domains are typically subsets of broadcast domains. Subnetting does not increase the number of IP addresses available. It increases the number of network IDs and, as a result, decreases the number of node IDs per network. It also creates more broadcast domains. Broadcasts are not forwarded by routers, so they are limited to the network on which they originate.

Link-Local Addresses

Think APIPA for IPv6 address fe80::/64 Link-local addresses are designated for use on a single local network. Linklocal addresses are automatically configured on all interfaces. This automatic configuration is comparable to the 169.254.0.0/16 APIPA automatically assigned IPv4 addressing scheme.

Site-Local Addresses

Think private address for IPv6 Address prefix FEC0::/10. Site-local addresses are equivalent to the IPv4 private address space (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16). As with IPv4, in which private address ranges are used in private networks, IPv6 uses site-local addresses that do not interfere with global unicast addresses. In addition, routers do not forward site-local traffic outside the site. Unlike link-local addresses, site-local addresses are not automatically configured and must be assigned through either stateless or stateful address configuration processes. The prefix used for the site-local address is FEC0::/10.

IPv4 Address Class B

A Class B address uses two octets to represent the network portion 128 to 191 Networks 16,384 65,534 hosts per network 10xxxxxx binary representation in the first octive Subnet 255.255.0.0 Private range 172.16.x.x to 172.31.255.255

IPv4 Address Class C

A Class C address uses three octets to represent the network portion 192 to 223.255.255.255 Networks 2,097,152 254 hosts per network 110xxxxx binary representation in the first octive Subnet 255.255.255.0 Private range 192.168.x.x

MAC address format

A MAC address is sometimes called a physical address because it is physically embedded in the interface. A MAC address is a 6-byte (48-bit) hexadecimal address that enables a NIC to be uniquely identified on the network. The MAC address forms the basis of network communication, regardless of the protocol used to achieve network connection. Because the MAC address is so fundamental to network communication, mechanisms are in place to ensure that duplicate addresses cannot be used. MAC addresses are expressed in hexadecimal, only the numbers 0 through 9 and the letters A through F can be used in them.

broadcast

A broadcast address is at the opposite end of the spectrum from a unicast address. A broadcast address is an IP address that you can use to target all systems on a subnet or network instead of single hosts. In other words, a broadcast message goes to everyone on the network.

Public vs. Private

A public network is a network to which anyone can connect. The best (and perhaps only pure) example of such a network is the Internet. A private network is any network to which access is restricted. A corporate network and a network in a school are examples of private networks.

Multicast IPv6

As with IPv4 addresses, multicasting sends and receives data between groups of nodes. It sends IP messages to that group rather than to every node on the LAN (broadcast) or just one other node (unicast).

CIDR

Classless Interdomain Routing (CIDR) the standard Class A, B, and C structure that is used by IPv6. Specifying the number of bits in the subnet mask offers more flexibility than the three standard class definitions. Using CIDR, addresses are assigned using a value known as the slash. The actual value of the slash depends on how many bits of the subnet mask are used to express the network portion of the address. For example, a subnet mask that uses all 8 bits from the first octet and 4 from the second would be described as /12, or "slash 12." A subnet mask that uses all the bits from the first three octets would be called /24. Why the slash? In actual addressing terms, the CIDR value is expressed after the address, using a slash. So the address 192.168.2.1/24 means that the node's IP address is 192.168.2.1, and the subnet mask is 255.255.255.0.

IPv4 Address Classes

IP addresses are grouped into logical divisions called classes. The IPv4 address space has five address classes (A through E); although, only three (A, B, and C) assign addresses to clients. Class D is reserved for multicast addressing, and Class E is reserved for future development. Of the three classes available for address assignments, each uses a fixed-length subnet mask to define the separation between the network and the node address.

IPv6 loop back Address

IPv4 reserves 127.0.0.1 as the loopback address. IPv6 has the same reservation. IPv6 addresses 0:0:0:0:0:0:0:0 and 0:0:0:0:0:0:0:1(::1) are reserved as the loopback addresses.

IPv6

IPv6 uses a 128-bit addressing scheme An IPv6 address is divided along 16-bit boundaries, and each 16-bit block is converted into a four-digit hexadecimal number and separated by colons. IPv6 address has eight fields, and each field contains four hexadecimal digits. The following formula reveals why an IPv6 address is a 128-bit address: 4 bits per digit * 4 digits per field * 8 fields = 128 bits in an IPv6 address 2001:0:4137:9e50:2811:34ff:3f57:febc 8 groups of 16bits Leading 0s in a field can be omitted. Contiguous fields containing all 0s can be represented with a double colon.(Note: This can be done only once for a single IPv6 address.)

Subnet Mask Assignment

Like an IP address, a subnet mask is most commonly expressed in 32-bit dotted- decimal format. Unlike an IP address, though, a subnet mask performs just one function—it defines which parts of the IP address refer to the network address and which refer to the node address

Multicast

Multicasting is a mechanism by which groups of network devices can send and receive data between the members of the group at one time, instead of separately sending messages to each device in the group. The multicast grouping is established by configuring each device with the same multicast IP address.

VLSM

Variable Length Subnet Masking Is a technique that allows network administrators to divide an IP address space to subnets of different sizes

unicast

With a unicast address, a single address is specified. Data sent with unicast addressing is delivered to a specific node identified by the address. It is a point-to-point address link.

Unicast IPv6

a unicast address specifies a single interface. Data packets sent to a unicast destination travel from the sending host to the destination host. It is a direct line of communication.