Configuring the IP settings

To configure networking and the connectivity between these networks, you must understand and familiarize yourself with the IPv4 or IPv6 addresses and how they work. Computers can only communicate if they can identify each other. In this section, you will learn about the IPv4 and IPv6 addresses.

Understanding the IPv4 address

You have to assign a unique IPv4 address to each computer, which is connected to the network so that the computer can identify itself to the other network-connected computers. This IPv4 address, combined with the subnet mask, will determine the location of the computer on the network. You can relate this to a street name and house number to identify the address of a house.

In the following diagram, you can see an example of the IPv4 addresses on a network:

Figure 8.1 - An example of the IPv4 addresses on a network

In the previous diagram, you can see two different subnets. Computers located on their own subnet can reach each other, but if they want to reach a computer on the other subnet, they have to send a request via a gateway. You will learn about this process in the next section.

Connecting with another network host

In a typical situation, for successful communication between computers, several steps will occur. These steps are as follows:

1. A source host sends a request to connect to a destination host. The name of the destination host must be resolved to an IPv4 address.
2. Once the source host knows the destination's host IPv4 address, it uses the subnet mask to determine whether the IPv4 address is on a remote subnet or the local subnet.
3. If its destination host is on the local subnet, an Address Resolution Protocol (ARP) request is broadcasted on the local subnet. If its destination host is on a remote subnet, an ARP request is sent to the default gateway and then directed to the correct subnet.
4. The destination host that owns that IPv4 address will respond with its Media Access Control (MAC) address and a request is sent to the source's host MAC address.
5. After the exchange of MAC addresses is completed, the IPv4 communication starts and the transfer of IP data packets can occur.

IPv4 makes use of 32-bit addresses. If you switch this to a binary format, then the address has 32 characters. This format will look as follows:

11000000101010000100111000010100

IPv4 divides this address into four octets. These four octets will look as follows:

11000000.10101000.01001110.00010100

Now, take a look at this explanation of the preceding binary format with the corresponding decimal format:

• The first octet is 11000000 and, if you switch this to decimal, the result is 192.
• The second octet is 10101000 and, if you switch this to decimal, the result is 168.
• The third octet is 01001110 and, if you switch this to decimal, the result is 78.
• The fourth octet is 00010100 and, if you switch this to decimal, the result is 20.

The complete IP address is then 192.168.78.20.

Along with a subnet mask, the address identifies the computer's unique identity—which is the host ID—and the subnet that the computer resides on—which is the network ID.

This type of communication allows a computer connected to a network to communicate with other computers connected to the same network in a routed environment.

The Internet Assigned Numbers Authority (IANA) arranges the IPv4 addresses into classes. The number of hosts in a network governs the required class of addresses. Class A through Class E are the names that IANA has detailed for the IPv4 address classes.

Class A, Class B, and Class C are IP addresses that can be assigned to host computers as a unique IP address, while Class D can be used for multicasting. Additionally, IANA reserves Class E for experimental use.

Defining subnets

A subnet is a network segment. Single or multiple routers separate the subnet from the rest of the network. When your Internet Service Provider (ISP) assigns a network to a Class A, Class B, or Class C address range, you often must subdivide the range to match the network's layout. Subdividing allows you to break a large network into smaller, logical subnets.

When you subdivide a network into subnets, you must create a unique ID for each subnet, which you derive from the primary network ID.

A subnet mask helps differentiate between the network ID and the host ID of an IPv4 address, as shown in the following table:

Table 8.1 - Subnet mask differentiation

If you use subnets, you can make use of Class A, Class B, or Class C networks across multiple locations. With subnets, you can also reduce network congestion. You can achieve this by segmenting network traffic and reducing broadcasts on every network segment. With subnets, you can overcome the limitations, such as exceeding the maximum number of hosts that each segment can handle. Just like an IPv4 address, the subnet mask also has four octets to specify which part is the network ID and which part is the host ID.

In more common IPv4 networks, the subnet mask defines full octets as part of the network ID and host ID. 255 corresponds to an octet that is part of the network ID and 0 corresponds to an octet that is part of the host ID. Class A, Class B, and Class C networks use the default subnet masks. The properties of each IP address class are shown in the following table:

Table 8.2 - IP address class properties

In complex networks, such as in an organization, subnet masks might not be a simple combination of 255 and 0. As an alternative, you can split one octet, with some parts used for the network ID and some parts used for the host ID.

We use Classless Inter-Domain Routing (CIDR) methods to define subnets. This subnetting uses a different notation, which is shown in the following example:

172.16.78.20/255.255.248.0

The following classless IPv4 address is more representative:

172.16.78.20/21

/21 represents how many bits are set to 1 in the subnet mask. This is an example of CIDR and this subnet mask now looks as in the following line in binary notation:

11111111.11111111.11111000.00000000

As you can see in the previous example, the first 21 bits are set to 1 and they indicate the subnet ID. The last 11 bits are set to 0 and they show how many bits are used to identify the host.

Now, let's understand how to use these subnets for connectivity.

Configuring connectivity to other subnets

A default gateway is a device on a network that serves as a forwarding host—usually, a router—which sends IP packets to different subnets when there is no other route specification that matches the destination IP address of an IP packet.

A router connects multiple subnets to create an intranet. In an intranet, any specified subnet might have more routers that connect to other local and remote subnets. To accomplish this, you must configure one of the routers as the default gateway for the local hosts so that the local hosts can communicate with the remote hosts. In most cases, you can use a Dynamic Host Configuration Protocol (DHCP) server to assign the default gateway automatically to a DHCP client. This is more straightforward than manually assigning a default gateway to each host.

Networks can contain public or private IP addresses. In the next section, you will learn the difference between the two.

Learning about public and private IP addresses

In general, hosts that are connecting directly to the internet require a public IPv4 address. However, hosts that do not link directly to the internet do not need a public IPv4 address. The public IPv4 address must be unique. IANA assigns public IPv4 addresses. Typically, your ISP allocates you one or more public IPv4 addresses from their dedicated IPv4 address pool.

The IPv4 address pool is becoming smaller, so IANA is unwilling to allocate unnecessary IPv4 addresses. Nowadays, you have technology such as Network Address Translation (NAT) that allows administrators to use a small piece of the public IPv4 addresses pool. At the same time, administrators can allow hosts on a local network to connect to hosts on the remote network and many services on the internet.

In the following table, you will see what IANA defines as the private IPv4 ranges:

Table 8.3 - Private IPv4 ranges

Routers that are connected to the internet will not forward packets initiating from, or intended for, the previously given ranges.

In networks nowadays, it is most common for organizations to have one or more public, routable IP addresses assigned to the external interfaces of their firewall appliances. For internal purposes, they use the designated private IPv4 ranges.

Assigning a host manually to an IPv4 address is a lot of work, as you already learned in an earlier section. In the next section, you will learn how you can implement automatic IPv4 addresses.

Implementing automatic IPv4 addressing

You can configure a static IPv4 configuration manually for each of your network-connected hosts. However, when you perform a manual IPv4 configuration, you must set the IPv4 address, the subnet mask, the default gateway, and the Domain Name Server (DNS) server. Static configuration is time-consuming and requires you to visit each host and configure the IPv4 configuration.

DHCP enables you, as an administrator, to assign IPv4 configurations automatically for a substantial number of computers without having to assign each one separately. The DHCP server receives requests for IPv4 addresses from hosts that you have configured to obtain an IPv4 address automatically. It also assigns IPv4 addresses from other scopes that you have defined for each of your subnets. The DHCP server identifies which subnet the request originated from and assigns an IPv4 configuration from the relevant scope.

DHCP helps you, as an administrator, to simplify the IPv4 address configuration process. If your DHCP server is business-critical, then you must include resilience in your DHCP server's design. This is in case of failure of a single server; we have to make sure that it doesn't prevent the whole DHCP service from functioning. The other thing you must do is to configure the DHCP scopes carefully. If you make a mistake, then this can affect the whole network and can prevent communication between the hosts.

Every network that a device connects to, such as a home or work network, might require different IPv4 configurations. Windows 10 has support for an Automatic Private IP Addressing (APIPA) and an alternate static IP address, for this scenario. In the following screenshot, you will see how this looks in the properties box of your network card:

Figure 8.2 - The Alternative Configuration tab

You can use the Alternative Configuration tab to control the behavior of your Windows 10 device if the DHCP server is not reachable. Windows 10 assigns itself an APIPA IPv4 address automatically, somewhere in the range of 169.254.0.0 to 169.254.255.255. With this method, you can use a DHCP server at work and an APIPA address range on your home network without the need to reconfigure the IPv4 settings. This setup can be useful for troubleshooting DHCP issues if a device can't communicate with the DHCP server.

Now, you know a lot about IPv4 address and hosts communicating with each other via subnets. Next, you will learn about IPv6. What? Another IP address? Yes!

Understanding the IPv6 address

Most networks currently provide IPv4 addresses, but many networks also support IPv6 addresses. You must understand the differences between IPv4, IPv6, and the IPv6 addressing scheme. Windows 10 devices use IPv6 by default, but they also support IPv6 and IPv4 in a dual-stack configuration.

The IPv6 protocol provides many benefits over IPv4. These benefits are as follows:

• Larger address spaces: A 32-bit address space can have 4,294,967,296 possible IPv4 addresses, whereas IPv6 uses 128-bit address spaces, which results in 340,282,366,920,938,463,463,374,607,431,768,211,456 possible IPv6 addresses.
• More efficient routing: IPv6 reduces the size of routing tables, making them more efficient and hierarchical to navigate. IPv6 allows ISPs to combine their consumer network prefixes into a single prefix and to announce this one prefix to the IPv6 internet. Besides, fragmentation in IPv6 networks is handled by the source device, rather than the router, using a protocol to determine the Maximum Transmission Unit (MTU) of the path.
• More efficient packet processing: The simpler packet header of IPv6 makes the processing of packets more secure. Similar to IPv4, IPv6 does not include an IP level checksum, so there is no need to recalculate the checksum at each router hop. It is possible to get rid of the checksum at the IP level because most link-layer technologies already provide checksum and error-control capabilities. Therefore, most transport layers, which handle end-to-end communication, have a checksum, allowing error detection.
• Direct data flows: IPv6 allows multicast, instead of broadcasting. Multicast provides simultaneous transmission of bandwidth-intensive packet flows (such as multimedia streams) to multiple destinations, saving network bandwidth. Disinterested hosts no longer need to process packets for transmission. However, the IPv6 header has a new field, called flow label, which can distinguish packets that belong to the same flow.
• Simplified network configuration: Auto-configuration of the address (address assignment) is built into IPv6. In the router advertisements, a router will send the local link prefix. By adding its link-layer (MAC) address and converting it into Extended Universal Identifier (EUI) 64-bit format, a host can generate its IP address.
• Support for new services: By removing NAT, true end-to-end communication is restored at the IP layer allowing new and useful services to be delivered.
• Security: For IPv6, Internet Protocol Security (IPsec) provides confidentiality, authentication, and data integrity. Corporate firewalls often block IPv4 Internet Control Message Protocol (ICMP) packets because of their ability to carry malware; however, Internet Control Message Protocol version 6 (ICMPv6—which is the implementation of the ICMP for IPv6—can be enabled because IPsec can be applied to the ICMPv6 packets.

If you connect to a new network that advertises IPv6 routability, Windows 10 can check the IPv6 connectivity and use IPv6 only if the IPv6 connectivity works. Windows 10 also provides an address-sorting feature. This feature lets the Windows 10 OS decide which protocol to use when all protocol stacks are configured to support applications that support IPv4 and IPv6 addresses.

Windows 10 device utilities, such as sharing files and remote access, use IPv6 technology, such as IPsec. This includes VPN Reconnect, which uses version 2 of Internet Key Exchange (IKEv2), a part of IPv6 authentication.

Windows 10 supports remote troubleshooting capabilities, such as Remote Desktop and Windows Remote Assistance. Remote Desktop lets administrators connect, for remote management, to multiple Windows Server sessions. To make remote desktop connections, you can use the IPv6 addresses, such as Windows Remote Assistance and Remote Desktop. These applications use Remote Desktop Protocol to allow users to access files from other computers, such as from their home computers to their office computers.

An overview of IPv6 addressing

IPv6's most noticeable distinguishing feature is its use of much larger addresses. IPv4 addresses are represented by four decimal numeral classes, such as 192.168.80.72. Each numeral class represents a binary octet. In binary format, the preceding number looks as follows:

11000000.10101000.01001110.00010100

For IPv6, the size of an address is four times that of an IPv4 address. As the following example shows, the IPv6 addresses are represented in hexadecimal form:

0:0:0:0:0:ffff:c0a8:5014

The previous hexadecimal string may seem confusing for end users, but the presumption is that users will rely on DNS names to handle hosts, ensuring that IPv6 addresses will only be typed by hand. In hexadecimal form, the IPv6 address is also easier to convert into binary form. This makes working with subnets and measuring hosts and networks simpler.

In the next section, we will learn about the types of IPv6 addresses.

Understanding the types of IPv6 addresses

The types of IPv6 addresses are similar to those of IPv4 addresses. The types of IPv6 addresses are, namely, unicast, multicast, and anycast.

The following sections will explain each one in detail. Let's start with unicast, first.

Unicast

A unicast IPv6 address is the same as a unicast IPv4 address. You can use this type of address to communicate between hosts one to one. Every IPv6 host has several unicast addresses. There are three types of unicast addresses:

• Global unicast address: These are similar to addresses for public IPv4. These addresses are routable worldwide and available on the internet portion of IPv6.
• Link-local addresses: Hosts use the connection local addresses when communicating on the same channel with neighboring hosts—for example, hosts communicate using link-local addresses on a single-link IPv6 network with no router. Link-local addresses always start with FE80 and they are equivalent to the IPv4 APIPA addresses.
• Unique local unicast addresses: Unique local addresses provide organizations with an equivalent of a private IPv4 address space, without the duplication in address space when organizations combine.

We will now move on to multicast.

Multicast

A multicast IPv6 address is the equivalent of a multicast IPv4 address. You use this type of address for one-to-many computer communication between computers that use the same multicast address.

Anycast

An anycast address is an IPv6 address allocated to multiple computers. When IPv6 addresses communicate to an anycast address, only the closest host will answer. Usually, you use this type of address to locate services or the nearest router.

You now understand the types of IPv6 addresses. In the next section, you will learn about the interface identifiers and their purposes.

Learning about the IPv6 interface identifiers

In IPv4, you typically assign a single unicast address to one host. In IPv6, however, each host can be assigned multiple unicast addresses. You need to know why IPv6 uses each of those addresses to verify communication processes on a network.

The interface identifier is the last 64 bits of an IPv6 address. This is similar to an IPv4 address host ID. Every interface on an IPv6 network must have a unique identifier for the interface. Because the interface identifier is unique to each interface, IPv6 uses interface identifiers to mark hosts individually, rather than MAC addresses.

That's it for IPv4 and IPv6. You now know the difference between these two IP addresses and how this technology works in a network. In the next section, we are going to learn how we can make use of mobile networking by using cellular networks, such as 4G or Long-Term Evolution (LTE).