Host A sends a segment with the SYN bit set, letting the other device know it wants to synchronize. The segment includes the initial sequence number of 5 that Host A is using. Host B accepts the segment to establish a session and sends back a segment with the SYN bit set. The acknowledgement number represents the next segment it expects to receive, which is 6 this is also called an expectational acknowledgment.
The new segment includes the initial sequence number of Host B, which is Host A replies with an ACK segment that contains a sequence of 6, because this is what Host B is expecting, and acknowledgement number 15, informing Host B that it can send the next segment. The window size informs the remote host about the number of bytes a device will accept before it must send an acknowledgement. However, the window sizes may not match on the two endpoints.
Host A has a window size of 2 and Host B has a window size of 3. When Host A sends data, it can send 3 bytes before waiting for an acknowledgement, whereas Host B can send only 2 bytes before receiving an ACK. Note : The window size specifies the number of bytes octets a device will accept, not the number of segments. After all the data is sent between the two hosts, the session can be closed. The segment includes the sequence number Host B is using at that specific moment, which is Host B acknowledges the request and sends the ACK bit with the acknowledgement number to confirm it has received number The segment also includes the current sequence number of Host B, which is Host B sends a new segment with the FIN bit set, announcing the application it is running also requests closing the session.
In the last step before the session is closed, Host A sends an ACK segment with number to confirm it received number from Host B. Once the MAC address is known, it is used as a destination address in the frames sent in that specific direction.
The Transport Layer is based on the following two protocols: Transmission Control Protocol TCP : This provides a connected-oriented transmission, meaning the path that the data travels on in the network is reliable, as the endpoints establish a synchronized connection before sending the data.
We separate those numbers with dots and that becomes a dotted decimal notation that we typically use to refer to IP addresses. The question becomes: how do we identify the network portion of the address and the host portion of the address?
In the early days of the Internet, the IANA, or Internet Assigned Numbers Authority, came up with the classful addressing scheme in which the class of the address defines the number of bits dedicated to the network ID, and the number of bits dedicated to the host ID, as well as the boundary between the two in or within the IP address. The address classes were identified and defined by a bit sequence at the start of the first octet. And so, just by looking at the first octet, you can tell which class we are talking about.
All addresses starting with a zero. In the most significant bit of the first octet will be a class A address.
Class A addresses reserve the first octet to represent the network ID while the second, third, and fourth octets represent the host ID. This made sense in the early Internet because we had very few networks with a large number of hosts, typically universities, government, and military sites.
Class B addresses are identified by a one and a zero in the first two bits of the first octet, and they reserve two bytes for the network and two bytes for the host. Similarly, class C start with and reserve three octets for the network and one octet for the host.
In the end, building an IP address means assigning unique host identifiers to devices within a network, and then giving them all the same network ID because they belong to the same network, similar to house numbers that are different within the street, but the street name is the same.
Two takeaways from the classful strategy: one, as human beings are either not too smart or too lazy to identify the bit sequence in the first octet, and so we convert that to decimal numbers and that gives us a good range of addresses or numbers to identify each class.
So, the first octet is between 1 to , then we are talking about Class A. Just by looking at the first octet and seeing it between and , we are talking about Class B. And, if the range of that first octet is through , then this a Class C. Notice that some numbers are missing; is nowhere to be found. Well, is one of the reserved addresses that cannot be assigned to a network and is used for loopback testing.
The second takeaway is that we are still working with a finite number of bits, and so the more octets we use for the network, the fewer bits we are going to have for the host and vice versa.
And so, if class A reserve 1 byte for the network and three for the host, then we have that number of possible hosts that can be represented with a class A network. Class B has that number, and Class C, and provide up to hosts. This one is surprising due to the fact that class C reserves one octet 8 bits to the host and two to the eighth power, according to binary logic, results in numbers. So initially and conceptually, I should be able to represent up to hosts for a class C.
However, there are some reserved addresses that cannot be used to assign to devices. All zeroes in the host portion of an IP address represent the network itself.
For example, if I have the It's got all zeroes in the host portion. Similarly, all ones in the host portion of the address is also reserved. It represents a broadcast within that network. A broadcast is nothing more than information that will reach all devices, so broadcast destination is heard and processed by all devices.
All ones, in one octet is translated into the number in decimal notation. So, for example, the address This type of broadcast is considered a directed broadcast in that network. However, the biggest broadcast is all ones in all bits.
This is what is called a local broadcast, and local broadcasts are nonroutable. The Internet is the network of networks, the ultimate public network that interconnects devices globally. Following basic IP rules, those devices will need to have a unique IP address, this time, again globally, worldwide. Duplication of addresses would cause instability in the Internet, as information may reach the wrong destination if it is duplicated, or to different sources with the same IP would cause inconsistencies at the destination level.
With that, they guarantee that there is no duplication, and everything is controlled by a central authority for IP address assignments. Soon enough, this was distributed in the centralized and multiple authorities raised geographically located, and so, APNIC allocates IP addresses for Asia Pacific geographies.
With the volume of devices out in the public network, it became apparent that the 32 bits on the IPv4 IP address would not be sufficient. IPv4 is a current version of IP commercially available and operational on the Internet. The newer IPv6 is starting to gain ground, and soon enough will become the standard on that network.
Meanwhile, intermediate solutions were found to allow for more and more devices to obtain an IP address without it needing to be public.
The private address ranges listed here for class A, B, and C can be used internally, and the organizational network allocated and assigned according to organizational rules, which are independent of the Internet and then translated to a public address when traffic or packets needed to access a public network.
While within the confines of the organizational network, the private addressing can be used when going to the public network, they would have to obtain an public IP address. This process of translation is called NAT, or network address translation. The private address ranges do not have any meaning on the Internet and are not routable on that network, meaning that IP packets with those addresses as a source or destination will be basically dropped on Internet routers. These private addresses are defined on RFC Once you have completed your design of IP addresses, you can now allocate, and assign, and configure IP addresses on devices.
You would have to follow basic rules. Let's say, all machines or devices in one's network will need to have the same network ID and unique host IDs. The configuration of IP addresses in devices can become cumbersome and difficult to manage, depending on the volume and number of devices.
This protocol is used to automatically assign IP addresses without human intervention.
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