To make clear that the total communications facility may consist of multiple networks, the constituent networks are usually referred to as subnetworks. This protocol enables the host to send data across the subnetwork to another host or, if the target host is on another subnetwork, to a router that will forward the data. IP is implemented in all of the end systems and the routers. It acts as a relay to move a block of data from one host, through one or more routers, to another host.
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At router J, the packet header is stripped off and the IP header examined. On the basis of the destination address information in the IP header, the IP module in the router directs the datagram out across subnetwork 2 to B.
TCP and UDP
TCP provides a reliable connection for the transfer of data between applications : A logical connection refers to a given pair of port values. In addition to TCP, there is one other transport-level protocol that is in common use as part of the TCP/IP protocol suite: the User Datagram Protocol (UDP). UDP does not guarantee delivery, preservation of sequence, or protection against duplication.
UDP enables a procedure to send messages to other procedures with a minimum of protocol mechanism : for example, SNMP (Simple Network Management Protocol).
IP and IPv6
For decades, the keystone of the TCP/IP protocol architecture has been IP.
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ECN : Explicit congestion notification field
TCP/IP Applications
A number of applications have been standardized to operate on top of TCP :
SMTP (Simple Mail Transfer Protocol): basic electronic mail transport facility, mechanism for transferring messages among separate hosts. Once a message is created, SMTP accepts the message and makes use of TCP to send it to an SMTP module on another host.
FTP (File Transfer Protocol) : used to send files from one system to another under user command. FTP sets up a TCP connection to the target system for the exchange of control messages. This connection allows user ID and password to be transmitted and allows the user to specify the file and file actions desired.
TELNET : provides a remote logon capability, which enables a user at a terminal or personal computer to logon to a remote computer and function as if directly connected to that computer. TELNET is implemented in 2 modules (user telnet which interacts with the terminal I/O module to communicate with a local terminal & server telnet which interacts with an app, acting as a surrogate terminal handler) - Traffic between the 2 modules is carried on a TCP connection.
etc.
Protocol Interfaces
Each layer in the TCP/IP protocol suite interacts with its immediate adjacent layers. This use of each individual layer is not required by the architecture.
Most applications require a reliable end-to-end protocol and thus make use of TCP. Some special-purpose applications do not need the services of TCP. Some of these applications, such as the Simple Network Management Protocol (SNMP), use an alternative end-to-end protocol known as the User Datagram Protocol (UDP); others may make use of IP directly.
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What is the major function of the network access layer?
The network access layer is the lowest layer in the Internet reference model. This layer contains the protocols that the computer uses to deliver data to the other computers and devices that are attached to the network. The protocols at this layer perform three distinct functions:
They define how to use the network to transmit a frame, which is the data unit passed across the physical connection.
They exchange data between the computer and the physical network.
They deliver data between two devices on the same network. To deliver data on the local network, the network access layer protocols use the physical addresses of the nodes on the network. A physical address is stored in the network adapter card of a computer or other device, and it is a value that is "hardcoded" into the adapter card by the manufacturer.
What tasks are performed by the transport layer?
Responsible for providing end-to-end data integrity and provides a highly reliable communication service for entities that want to carry out an extended two-way conversation.
What is a protocol?
A set of rules and guidelines for communicating data. Rules are defined for each step and process during communication between two or more computers. Networks have to follow these rules to successfully transmit data.
What is a protocol data unit (PDU)?
The basic unit of exchange between entities that communicate using a specified networking protocol. When working with a multilayer protocol stack, like the TCP/IP networking suite, use of the correct PDU is important when discussing protocol interactions.
What is a protocol architecture?
Layered structure of hardware and software. that supports the exchange of data between. systems as well as a distributed application.
What is TCP/IP?
The name TCP/IP refers to a suite of data communication protocols. The name is misleading because TCP and IP are only two of dozens of protocols that compose the suite. Its name comes from two of the more important protocols in the suite: the Transmission Control Protocol (TCP) and the Internet Protocol (IP).
What are some advantages to layering as seen in the TCP/IP architecture?
It provides scalability and flexibility to the model.
It allows multiple applications to reuse the components which ensures saving the cost.
It allows various teams to work on different part of applications.
What is a router?
Two types of devices are responsible for routing messages between networks. The first device is called a gateway, which is a computer that has two network adapter cards. This computer accepts network packets from one network on one network card and routes those packets to a different network via the second network adapter card. The second device is a router, which is a dedicated hardware device that passes packets from one network to a different network.
Does all traffic running on the Internet use TCP?
No, some internet traffic uses UDP instead.
Compare the address space between IPv4 and IPv6. How many bits are used in each?
The address space in IPv4 is 20 octets, while in IPv6 it's 40 octets. While IPv4 is 32 bits, IPv6 is 128 bits.
List the major disadvantages with the layered approach to protocols.
-Processing overhead.
-Data overhead.