Unit – 3
Network Layer
Point - to - Point Protocol (PPP) is a communication protocol of the data link layer that is used to transmit multiprotocol data between two directly connected (point-to-point) computers. It is a byte - oriented protocol that is widely used in broadband communications having heavy loads and high speeds. Since it is a data link layer protocol, data is transmitted in frames. It is also known as RFC 1661.
The main services provided by Point - to - Point Protocol are
Fig 1: point to point connection
Point - to - Point Protocol is a layered protocol having three components −
Encapsulation Component − It encapsulates the datagram so that it can be transmitted over the specified physical layer.
Link Control Protocol (LCP) − It is responsible for establishing, configuring, testing, maintaining and terminating links for transmission. It also imparts negotiation for set up of options and use of features by the two endpoints of the links.
Authentication Protocols (AP) − These protocols authenticate endpoints for use of services. The two authentication protocols of PPP are
Password Authentication Protocol (PAP)
Challenge Handshake Authentication Protocol (CHAP)
Network Control Protocols (NCPs) − These protocols are used for negotiating the parameters and facilities for the network layer. For every higher-layer protocol supported by PPP, one NCP is there.
Key takeaway:
What is IP?
An IP stands for internet protocol. An IP address is assigned to each device connected to a network. Each device uses an IP address for communication. It also behaves as an identifier as this address is used to identify the device on a network. It defines the technical format of the packets. Mainly, both the networks, i.e., IP and TCP, are combined together, so together, they are referred to as TCP/IP. It creates a virtual connection between the source and the destination.
We can also define an IP address as a numeric address assigned to each device on a network. An IP address is assigned to each device so that the device on a network can be identified uniquely. To facilitate the routing of packets, TCP/IP protocol uses a 32-bit logical address known as IPv4(Internet Protocol version 4).
IPv4 on its own does not provide any security feature which is vulnerable as data on the Internet, which is a public domain, is never safe. Data has to be encrypted with some other security application before being sent on the Internet. Data prioritization in IPv4 is not up to date. Though IPv4 has few bits reserved for Type of Service or Quality of Service, they do not provide much functionality.
IPv4 enabled clients can be configured manually or they need some address configuration mechanism. There exists no technique which can configure a device to have globally unique IP addresses.
An IP address consists of two parts, i.e., the first one is a network address, and the other one is a host address.
There are two types of IP addresses:
● IPv4
● IPv6
What is IPv4?
IPv4 is a version 4 of IP. It is a current version and the most commonly used IP address. It is a 32-bit address written in four numbers separated by 'dot', i.e., periods. This address is unique for each device.
For example, 66.94.29.13
The above example represents the IP address in which each group of numbers separated by periods is called an Octet. Each number in an octet is in the range from 0-255. This address can produce 4,294,967,296 possible unique addresses.
In today's computer network world, computers do not understand the IP addresses in the standard numeric format as the computers understand the numbers in binary form only. The binary number can be either 1 or 0. The IPv4 consists of four sets, and these sets represent the octet. The bits in each octet represent a number.
Each bit in an octet can be either 1 or 0. If the bit is 1, then the number it represents will count, and if the bit is 0, then the number it represents does not count.
Representation of 8 Bit Octet
Fig 2: structure of 8-bit octet
The above representation shows the structure of 8- bit octet.
Now, we will see how to obtain the binary representation of the above IP address, i.e., 66.94.29.13
Step 1: First, we find the binary number of 66
To obtain 66, we put 1 under 64 and 2 as the sum of 64 and 2 is equal to 66 (64+2=66), and the remaining bits will be zero, as shown above. Therefore, the binary bit version of 66 is 01000010.
Step 2: Now, we calculate the binary number of 94
To obtain 94, we put 1 under 64, 16, 8, 4, and 2 as the sum of these numbers is equal to 94, and the remaining bits will be zero. Therefore, the binary bit version of 94 is 01011110.
Step 3: The next number is 29
To obtain 29, we put 1 under 16, 8, 4, and 1 as the sum of these numbers is equal to 29, and the remaining bits will be zero. Therefore, the binary bit version of 29 is 00011101.
Step 4: The last number is 13
To obtain 13, we put 1 under 8, 4, and 1 as the sum of these numbers is equal to 13, and the remaining bits will be zero. Therefore, the binary bit version of 13 is 00001101.
Drawback of IPv4
Currently, the population of the world is 7.6 billion. Every user is having more than one device connected with the internet, and private companies also rely on the internet. As we know that IPv4 produces 4 billion addresses, which is not enough for each device connected to the internet on a planet.
Although various techniques were invented, such as variable- length mask, network address translation, port address translation, classes, inter-domain translation, to conserve the bandwidth of IP address and slow down the depletion of an IP address. In these techniques, public IP is converted into a private IP due to which the user having public IP can also use the internet. But still, this was not so efficient, so it gave rise to the development of the next generation of IP addresses, i.e., IPv6.
Key takeaways:
IP
An IP stands for internet protocol. An IP address is assigned to each device connected to a network. Each device uses an IP address for communication. It also behaves as an identifier as this address is used to identify the device on a network. It defines the technical format of the packets. Mainly, both the networks, i.e., IP and TCP, are combined together, so together, they are referred to as TCP/IP. It creates a virtual connection between the source and the destination.
We can also define an IP address as a numeric address assigned to each device on a network. An IP address is assigned to each device so that the device on a network can be identified uniquely. To facilitate the routing of packets, TCP/IP protocol uses a 32-bit logical address known as IPv4(Internet Protocol version 4).
Function:
The internet protocol's main purpose is to provide hosts with addresses, encapsulate data into packet structures, and route data from source to destination through one or more IP networks. The internet protocol provides two main items in order to achieve these functionalities, which are mentioned below.
● Format of IP packet
● IP Addressing system
IP packet
Until an IP packet is sent over the network, it contains two main components: a header and a payload.
Fig 3: IP packet
An IP header provides a lot of details about the IP packet, such as:
● The source IP address is that of the person who is sending the data.
● IP address of the destination: The destination is a host that collects data from the sender.
● Header length
● Packet length
● TTL (Time to Live) of a packet is the amount of hops that must occur before the packet is discarded.
● The internet protocol's transport protocol, which can be TCP or UDP, is known as the transport protocol.
The IP header contains a total of 14 fields, one of which is optional.
The data to be transported is known as the payload.
CIDR
CIDR stands for Classless Inter-Domain Routing, and it is an IP addressing scheme that enhances IP address allocation. It replaces the old scheme of A, B, and C classes. This scheme also aided in extending the life of IPv4 and reducing the size of routing tables.
CIDR IP addresses are made up of two groups of numbers, also known as groups of bits. The network address is the most significant of these types, since it is used to define a network or a sub-network (subnet). The host identifier is the smallest of the bit classes. The host identifier is used to identify which network host or computer should accept incoming data packets.
A new paradigm of Classless Inter-Domain Routing has been implemented to minimize IP address waste. This technique is now used by IANA to provide IP addresses. When a user requests IP addresses, IANA will allocate the number of IP addresses to the user.
Representation: It's also a 32-bit address with a special number indicating the number of bits in the Block Id.
a. b. c. d / n
Where n is the number of bits in the Block Id / Network Id.
Example:
If you need to quickly figure out what IP range a given CIDR address corresponds to, the CIDR Calculation tool comes in handy. Simply type in the CIDR address and hit the Calculate button. The first IP, last IP, number of hosts, and other details will be returned.
Fig 4: example
Address Resolution Protocol (ARP)
Address Resolution Protocol (ARP) is a communication protocol used to find the MAC (Media Access Control) address of a device from its IP address. This protocol is used when a device wants to communicate with another device on a Local Area Network or Ethernet.
Types of ARP
There are four types of Address Resolution Protocol, which is given below:
● Proxy ARP
● Gratuitous ARP
● Reverse ARP (RARP)
● Inverse ARP
Fig 5: ARP
Proxy ARP - Proxy ARP is a method through which a Layer 3 device may respond to ARP requests for a target that is in a different network from the sender. The Proxy ARP configured router responds to the ARP and maps the MAC address of the router with the target IP address and fools the sender that it is reached at its destination.
At the backend, the proxy router sends its packets to the appropriate destination because the packets contain the necessary information.
Example - If Host A wants to transmit data to Host B, which is on the different network, then Host A sends an ARP request message to receive a MAC address for Host B. The router responds to Host A with its own MAC address pretending itself as a destination. When the data is transmitted to the destination by Host A, it will send to the gateway so that it sends to Host B. This is known as proxy ARP.
Gratuitous ARP - Gratuitous ARP is an ARP request of the host that helps to identify the duplicate IP address. It is a broadcast request for the IP address of the router. If an ARP request is sent by a switch or router to get its IP address and no ARP responses are received, so all other nodes cannot use the IP address allocated to that switch or router. Yet if a router or switch sends an ARP request for its IP address and receives an ARP response, another node uses the IP address allocated to the switch or router.
There are some primary use cases of gratuitous ARP that are given below:
● The gratuitous ARP is used to update the ARP table of other devices.
● It also checks whether the host is using the original IP address or a duplicate one.
Reverse ARP (RARP)
It is a networking protocol used by the client system in a local area network (LAN) to request its IPv4 address from the ARP gateway router table. A table is created by the network administrator in the gateway-router that is used to find out the MAC address to the corresponding IP address.
When a new system is set up or any machine that has no memory to store the IP address, then the user has to find the IP address of the device. The device sends a RARP broadcast packet, including its own MAC address in the address field of both the sender and the receiver hardware. A host installed inside of the local network called the RARP-server is prepared to respond to such type of broadcast packet. The RARP server is then trying to locate a mapping table entry in the IP to MAC address. If any entry matches the item in the table, then the RARP server sends the response packet along with the IP address to the requesting computer.
Fig 6: RARP
Inverse ARP (In ARP) - Inverse ARP is inverse of the ARP, and it is used to find the IP addresses of the nodes from the data link layer addresses. These are mainly used for the frame relays, and ATM networks, where Layer 2 virtual circuit addressing are often acquired from Layer 2 signaling. When using these virtual circuits, the relevant Layer 3 addresses are available.
ARP conversions Layer 3 addresses to Layer 2 addresses. However, its opposite address can be defined by In ARP. The In ARP has a similar packet format as ARP, but operational codes are different.
Dynamic Host Configuration Protocol (DHCP)
Dynamic Host Configuration Protocol (DHCP) is a network management protocol used to dynamically assign an IP address to any device, or node, on a network so they can communicate using IP (Internet Protocol). DHCP automates and centrally manages these configurations. There is no need to manually assign IP addresses to new devices. Therefore, there is no requirement for any user configuration to connect to a DHCP based network.
DHCP can be implemented on local networks as well as large enterprise networks. DHCP is the default protocol used by most routers and networking equipment. DHCP is also called RFC (Request for comments) 2131.
DHCP does the following:
● DHCP manages the provision of all the nodes or devices added or dropped from the network.
● DHCP maintains the unique IP address of the host using a DHCP server.
● It sends a request to the DHCP server whenever a client/node/device, which is configured to work with DHCP, connects to a network. The server acknowledges by providing an IP address to the client/node/device.
DHCP is also used to configure the proper subnet mask, default gateway and DNS server information on the node or device.
There are many versions of DHCP available for use in IPV4 (Internet Protocol Version 4) and IPV6 (Internet Protocol Version 6).
How DHCP works
DHCP runs at the application layer of the TCP/IP protocol stack to dynamically assign IP addresses to DHCP clients/nodes and to allocate TCP/IP configuration information to the DHCP clients. Information includes subnet mask information, default gateway, IP addresses and domain name system addresses.
DHCP is based on client-server protocol in which servers manage a pool of unique IP addresses, as well as information about client configuration parameters, and assign addresses out of those address pools.
The DHCP lease process works as follows:
● First of all, a client (network device) must be connected to the internet.
● DHCP clients request an IP address. Typically, clients broadcast a query for this information.
● DHCP server responds to the client request by providing IP server address and other configuration information. This configuration information also includes a time period, called a lease, for which the allocation is valid.
● When refreshing an assignment, a DHCP client requests the same parameters, but the DHCP server may assign a new IP address. This is based on the policies set by the administrator.
Components of DHCP
When working with DHCP, it is important to understand all of the components. Following is the list of components:
● DHCP Server: DHCP server is a networked device running the DCHP service that holds IP addresses and related configuration information. This is typically a server or a router but could be anything that acts as a host, such as an SD-WAN appliance.
● DHCP client: DHCP client is the endpoint that receives configuration information from a DHCP server. This can be any device like computer, laptop, IoT endpoint or anything else that requires connectivity to the network. Most of the devices are configured to receive DHCP information by default.
● IP address pool: IP address pool is the range of addresses that are available to DHCP clients. IP addresses are typically handed out sequentially from lowest to the highest.
● Subnet: Subnet is the partitioned segment of the IP networks. Subnet is used to keep networks manageable.
● Lease: Lease is the length of time for which a DHCP client holds the IP address information. When a lease expires, the client has to renew it.
● DHCP relay: A host or router that listens for client messages being broadcast on that network and then forwards them to a configured server. The server then sends responses back to the relay agent that passes them along to the client. DHCP relay can be used to centralize DHCP servers instead of having a server on each subnet.
Benefits of DHCP
There are following benefits of DHCP:
● Centralized administration of IP configuration: DHCP IP configuration information can be stored in a single location and enables that administrator to centrally manage all IP address configuration information.
● Dynamic host configuration: DHCP automates the host configuration process and eliminates the need to manually configure individual hosts. When TCP/IP (Transmission control protocol/Internet protocol) is first deployed or when IP infrastructure changes are required.
● Seamless IP host configuration: The use of DHCP ensures that DHCP clients get accurate and timely IP configuration IP configuration parameters such as IP address, subnet mask, default gateway, IP address of DND server and so on without user intervention.
● Flexibility and scalability: Using DHCP gives the administrator increased flexibility, allowing the administrator to easily change IP configuration when the infrastructure changes.
ICMP
The ICMP stands for Internet Control Message Protocol. The ICMP protocol is a network layer protocol that hosts and routers use to notify the sender of IP datagram problems. The echo test/reply method is used by ICMP to determine if the destination is reachable and responding.
ICMP can handle both control and error messages, but its primary purpose is to record errors rather than to fix them. An IP datagram includes the source and destination addresses, but it does not know the address of the previous router it passed through.
As a result, ICMP can only send messages to the source, not to the routers in the immediate vicinity. The sender receives error messages via the ICMP protocol. The errors are returned to the user processes via ICMP messages.
ICMP messages are sent as part of an IP datagram.
Fig 7: ICMP
Format of ICMP
Fig 8: ICMP format
● The message's form is defined in the first sector.
● The reason for a particular message form is specified in the second sector.
● The checksum field is used to verify the integrity of the entire ICMP message.
Key takeaways:
A Router is a process of selecting a path along which the data can be transferred from source to the destination. Routing is performed by a special device known as a router. A Router works at the network layer in the OSI model and internet layer in TCP/IP model A router is a networking device that forwards the packet based on the information available in the packet header and forwarding table.
The routing algorithms are used for routing the packets. The routing algorithm is nothing but a software responsible for deciding the optimal path through which packets can be transmitted. The routing protocols use the metric to determine the best path for the packet delivery. The metric is the standard of measurement such as hop count, bandwidth, delay, current load on the path, etc. used by the routing algorithm to determine the optimal path to the destination. The routing algorithm initializes and maintains the routing table for the process of path determination.
Routing Metrics and Costs
Routing metrics and costs are used for determining the best route to the destination. The factors used by the protocols to determine the shortest path, these factors are known as a metric. Metrics are the network variables used to determine the best route to the destination. For some protocols the static metrics means that their value cannot be changed and for some other routing protocols the dynamic metrics means that their value can be assigned by the system administrator.
The most common metric values are given below:
Hop count: Hop count is defined as a metric that specifies the number of passes through internetworking devices such as a router, a packet must travel in a route to move from source to the destination. If the routing protocol considers the hop as a primary metric value, then the path with the least hop count will be considered as the best path to move from source to the destination.
Delay: It is a time taken by the router to process, queue and transmit a datagram to an interface. The protocols use this metric to determine the delay values for all the links along the path end-to-end. The path having the lowest delay value will be considered as the best path.
Bandwidth: The capacity of the link is known as the bandwidth of the link. The bandwidth is measured in terms of bits per second. The link that has a higher transfer rate like gigabit is preferred over the link that has the lower capacity like 56 kb. The protocol will determine the bandwidth capacity for all the links along the path, and the overall higher bandwidth will be considered as the best route.
Load: Load refers to the degree to which the network resource such as a router or network link is busy. A Load can be calculated in a variety of ways such as CPU utilization, packets processed per second. If the traffic increases, then the load value will also be increased. The load value changes with respect to the change in the traffic.
Reliability: Reliability is a metric factor that may be composed of a fixed value. It depends on the network links, and its value is measured dynamically. Some networks go down more often than others. After network failure, some network links are repaired more easily than other network links. Any reliability factor can be considered for the assignment of reliability ratings, which are generally numeric values assigned by the system administrator.
Types of Routing
Routing can be classified into three categories:
● Static Routing
● Default Routing
● Dynamic Routing
Default Routing
Default Routing is a technique in which a router is configured to send all the packets to the same hop device, and it doesn't matter whether it belongs to a particular network or not. A Packet is transmitted to the device for which it is configured in default routing. Default Routing is used when networks deal with the single exit point. It is also useful when the bulk of transmission networks have to transmit the data to the same hp device. When a specific route is mentioned in the routing table, the router will choose the specific route rather than the default route. The default route is chosen only when a specific route is not mentioned in the routing table.
Key takeaway:
● The term "forwarding" refers to the process of placing a packet on its way to its intended destination.
○ Since the Internet today is made up of a series of connections, forwarding refers to the process of delivering a packet to the next hop.
● Despite the fact that the IP protocol was built to be a connectionless protocol, the trend today is to use IP as a connection-oriented protocol based on the label attached to an IP datagram.
● Based on the destination address, forwarding is performed.
○ Next-hop
○ Network- Specific Method
○ Host-Specific Method
○ Default Method
● Label-based forwarding.
Delivery
The network layer is in charge of overseeing how packets are handled by the physical networks under it. This is referred to as "packet distribution."
A packet may be sent to its final destination in one of two ways: direct or indirect.
Direct Delivery
● The packet's final destination is a host on the same physical network as the deliverer.
● The packet's source and destination are on the same physical network, and the packet is sent between the last router and the destination host.
● Extract the destination's network address and link it to the addresses of the networks to which it is connected.
○ If a match is found, the message is sent directly.
● The sender looks up the destination physical address using the destination IP address
Fig 9: direct delivery
Indirect Delivery
● The distribution is not on the same network as the destination host.
● The packet is passed from one router to the next before it enters a router that is connected to the same physical network.
● To find the IP address of the next router, the sender uses the destination IP address and a routing table.
Fig 10: indirect delivery
Key takeaway:
Static Routing
Static Routing is also known as Non-Adaptive Routing. It is a technique in which the administrator manually adds the routes in a routing table. A Router can send the packets for the destination along the route defined by the administrator. In this technique, routing decisions are not made based on the condition or topology of the network.
Advantages of Static Routing
● No Overhead: It has ho overhead on the CPU usage of the router. Therefore, the cheaper router can be used to obtain static routing.
● Bandwidth: It has no bandwidth usage between the routers.
● Security: It provides security as the system administrator is allowed only to have control over the routing to a particular network.
Disadvantages of Static Routing:
● For a large network, it becomes a very difficult task to add each route manually to the routing table. The system administrator should have a good knowledge of a topology as he has to add each route manually.
Dynamic Routing
It is also known as Adaptive Routing. It is a technique in which a router adds a new route in the routing table for each packet in response to the changes in the condition or topology of the network. Dynamic protocols are used to discover the new routes to reach the destination. In Dynamic Routing, RIP and OSPF are the protocols used to discover the new routes. If any route goes down, then the automatic adjustment will be made to reach the destination. The Dynamic protocol should have the following features: All the routers must have the same dynamic routing protocol in order to exchange the routes. If the router discovers any change in the condition or topology, then the router broadcasts this information to all other routers.
Advantages of Dynamic Routing:
● It is easier to configure.
● It is more effective in selecting the best route in response to the changes in the condition or topology.
Disadvantages of Dynamic Routing:
● It is more expensive in terms of CPU and bandwidth usage.
● It is less secure as compared to default and static routing.
Key takeaway:
A routing algorithm is a process that establishes the route or path for data packets to be transferred from source to destination. They aid in the efficient routing of Internet traffic. After leaving its source, a data packet can choose from a variety of paths to reach its destination. The best path, i.e,. the “least – cost path,” that the packet can be routed through is calculated mathematically by the routing algorithm.
Types of routing algorithm
Adaptive and nonadaptive routing algorithms are the two types of routing algorithms that can be used. They can be further classified as seen in the diagram below.
Fig 11: types of routing algorithm
Adaptive Routing Algorithm
Adaptive routing algorithms, also known as dynamic routing algorithms, make routing decisions based on network conditions in real time. It creates the routing table based on the traffic and topology of the network. They try to find the best route based on the number of hops, transit time, and size.
The three most popular adaptive routing algorithms are as follows:
● Centralized algorithm - It uses global network awareness to find the cheapest route between source and destination nodes. As a result, it's often referred to as the global routing algorithm.
● Isolated algorithm - Instead of collecting information from other nodes, this algorithm obtains routing information by using local information.
● Distributed algorithm - This is a distributed, iteratively computed decentralized algorithm that finds the cheapest path between source and destination.
Non - Adaptive Routing Algorithm
Adaptive failure Routing algorithms, also known as static routing algorithms, construct a static routing table to decide which direction packets should take. When the network is booted up, the static routing table is built using the routing information stored in the routers.
There are two kinds of non-adaptive routing algorithms.
● Flooding - When a data packet arrives at a router in flooding mode, it is sent to all outgoing links except the one on which it arrived. Uncontrolled, regulated, or selective flooding are all possibilities.
● Random walks - This is a probabilistic algorithm in which the router sends a data packet to all of its neighbors at random.
Key takeaway:
Congestion
When message traffic is so high that network response time is slowed, a state occurs in the network layer.
Congestion's Effects
● Output suffers as the delay lengthens.
● Retransmission happens as the delay increases, worsening the situation.
● Leaky Bucket Algorithm
Let us consider an example to understand
Imagine a bucket with a small hole in the bottom. No matter at what rate water enters the bucket, the outflow is at a constant rate. When the bucket is full with water additional water entering spills over the sides and is lost.
Fig 12: Leaky bucket algorithm
Similarly, each network interface contains a leaky bucket and the following steps are involved in leaky bucket algorithm:
● Token bucket Algorithm
Need of token bucket Algorithm:
The leaky bucket algorithm enforces output patterns at the average rate, no matter how bursty the traffic is. So, in order to deal with the bursty traffic we need a flexible algorithm so that the data is not lost. One such algorithm is the token bucket algorithm.
Steps of this algorithm can be described as follows:
Let’s understand with an example,
In the figure we see a bucket holding three tokens, with five packets waiting to be transmitted. For a packet to be transmitted, it must capture and destroy one token. In figure (B) We see that three of the five packets have gotten through, but the other two are stuck waiting for more tokens to be generated.
Ways in which token bucket is superior to leaky bucket:
The leaky bucket algorithm controls the rate at which the packets are introduced in the network, but it is very conservative in nature. Some flexibility is introduced in the token bucket algorithm. In the token bucket, algorithm tokens are generated at each tick (up to a certain limit). For an incoming packet to be transmitted, it must capture a token and the transmission takes place at the same rate. Hence some of the busty packets are transmitted at the same rate if tokens are available and thus introduces some amount of flexibility in the system.
Formula: M * s = C + ρ * s
where S – is time taken
M – Maximum output rate
ρ – Token arrival rate
C – Capacity of the token bucket in byte.
Key takeaway:
Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP) and the first version of the protocol to be widely deployed. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion. The Internet has grown exponentially and the address space allowed by IPv4 is saturating.
There is a requirement of protocol which can satisfy the need of future Internet addresses which are expected to grow in an unexpected manner. Using features such as NAT, has made the Internet discontinuous i.e. one part which belongs to intranet, primarily uses private IP addresses; which has to go through a number of mechanisms to reach the other part, the Internet, which is on public IP addresses.
What is IPv6?
IPv4 produces 4 billion addresses, and the developers think that these addresses are enough, but they were wrong. IPv6 is the next generation of IP addresses. The main difference between IPv4 and IPv6 is the address size of IP addresses. The IPv4 is a 32-bit address, whereas IPv6 is a 128-bit hexadecimal address. IPv6 provides a large address space, and it contains a simple header as compared to IPv4.
It provides transition strategies that convert IPv4 into IPv6, and these strategies are as follows:
● Dual stacking: It allows us to have both the versions, i.e., IPv4 and IPv6, on the same device.
● Tunneling: In this approach, all the users have IPv6 and communicate with an IPv4 network to reach IPv6.
● Network Address Translation: The translation allows the communication between the hosts having a different version of IP.
This hexadecimal address contains both numbers and alphabets. Due to the usage of both the numbers and alphabets, IPv6 is capable of producing over 340 undecillion (3.4*1038) addresses.
IPv6 is a 128-bit hexadecimal address made up of 8 sets of 16 bits each, and these 8 sets are separated by a colon. In IPv6, each hexadecimal character represents 4 bits. So, we need to convert 4 bits to a hexadecimal number at a time
The address format of IPv6:
Fig 13: address format of IPV6
The above diagram shows the address format of IPv4 and IPv6. An IPv4 is a 32-bit decimal address. It contains 4 octets or fields separated by 'dot', and each field is 8-bit in size. The number that each field contains should be in the range of 0-255. Whereas an IPv6 is a 128-bit hexadecimal address. It contains 8 fields separated by a colon, and each field is 16-bit in size.
Differences between IPv4 and IPv6
| Ipv4 | Ipv6 |
Address length | IPv4 is a 32-bit address. | IPv6 is a 128-bit address. |
Fields | IPv4 is a numeric address that consists of 4 fields which are separated by dot (.). | IPv6 is an alphanumeric address that consists of 8 fields, which are separated by colon. |
Classes | IPv4 has 5 different classes of IP address that includes Class A, Class B, Class C, Class D, and Class E. | IPv6 does not contain classes of IP addresses. |
Number of IP address | IPv4 has a limited number of IP addresses. | IPv6 has a large number of IP addresses. |
VLSM | It supports VLSM (Virtual Length Subnet Mask). Here, VLSM means that Ipv4 converts IP addresses into a subnet of different sizes. | It does not support VLSM. |
Address configuration | It supports manual and DHCP configuration. | It supports manual, DHCP, auto-configuration, and renumbering. |
Encryption and Authentication | It does not provide encryption and authentication. | It provides encryption and authentication. |
Address representation | In IPv4, the IP address is represented in decimal. | In IPv6, the representation of the IP address is hexadecimal. |
Packet flow identification | It does not provide any mechanism for packet flow identification. | It uses a flow label field in the header for the packet flow identification. |
Key takeaway:
References:
2. Andrew Tanenbaum “Computer Networks”, Prentice Hall.
3. William Stallings, “Data and Computer Communication”, Pearson.
4. Kurose and Ross, “Computer Networking- A Top-Down Approach”, Pearson.
