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Find the error in the following IPv4 addresses.
There should be no zero at the start i.e. before the decimal number (045) in each dotted decimal representation.
The IPv4 is represented using only 3 decimal dotted notations.
The maximum number in IPv4 is 255. So each number in IPv4 cannot be more than 255
The mixture of binary and decimal representation is not allowed
Find the class of the following IP addresses
The first decimal is 208 which falls between 192 to 223, Hence,it belongs to class C
The first decimal (238) falls between 224 to 239. Hence, the IP belongs to class D.
The first decimal falls between 0 to 127. Hence, the IP belongs to class A.
The first decimal falls between 128 to 191. Hence, the IP belongs to class B.
Find the netid and the hosted of the following IP addresses
The first decimal i.e. 114 represent the Net ID and the remaining decimals represent the host portions.
The first two decimals represent Net ID and the other two decimals represent Host portions.
The first three decimal portions represent Net ID and the last decimal represents host portion or host ID
Show the hexadecimal colon notation of the IPv6 addresses compatible to the IPv4 address 126.96.36.199.
Ans: The compatible IPv6 representation of address 188.8.131.52 (IPv4) is 0::8106:C22 or 0000:0000:0000:0000:0000:0000:8106:0C22
Write the following masks in slash notation (/n)
Match the following to one or more layers of the OSI model:
Interface to transmission media.
Provides user services such as e-mail and FTP.
Error correction and Re-transmission.
Log-in and log-out procedures.
Route Determination- Layer 3- Packet Layer
Flow Control- Layer 4 – Transport layer
Interface to transmission media- Layer 1- Physical layer
Route Selection – Layer 3- Network layer
Defines Frames- Layer 2 – Data Link layer
Provides services – Layer 7 – Application Layer
Error Correction and Retransmission – Layer 4 and layer 2
Log-in and Log-out Procedures – Layer 5 – Session Layer
Suppose a computer sends a frame to another computer on a bus topology LAN. The physical destination address of the frame is corrupted during the transmission. What happens to the frame? How can the sender be informed of the situation?
The data link layer checks MAC address table for sending the frame to the particular LAN port as mentioned in the table. In case, If the frame destination address is corrupted and it does not match with the addresses present in the address table, the frame will be discarded.
If the corrupted address matches with any of the other address mentioned in the table, the frame will be directed to that port and the CRC is performed at that side. As the CRC at destination will be different from the Source side CRC, the frame will be discarded.
Once the frame reaches the destination, the destination LAN will send the acknowledgement to the source stating that the frame is received successfully. In case, If source did not receive any acknowledgement from the destination, he will send the frame again.
Suppose a computer sends a packet to the transport layer to another computer somewhere on the Internet. There is no process with the destination port address running on the destination computer. What will happen?
A Special error message called “Port Unreachable” is sent back to the source address whenever there is no process at the destination port address
If the data link layer can detect errors between hops, why do we need extra checking requirements at the transport layer?
The Data link layer makes a reliable connection between the node to node whereas the actual communication happens between two processes one each at source and destination, handled by the transport layer. The network layer which lies between the data link layer and transport layer does not make any reliable communication because there is no error checking mechanism performed at this layer. So, there is a possibility for the data to get corrupted. In order to avoid the corrupted data transmission, the error checking is again performed at the transport layer.
What are headers and trailers, and how do they get added and removed?
The header is the information added at the start of protocol data unit and information appended at the end of protocol data unit is called a trailer. These units contain either source or destination addresses, or error checking mechanism or control bits. These units of information are added at the source side and get removed at the destination side.
What are the differences between port addresses, a logical address, and a physical address?
Physical address is an address of the node(NIC slot) which is assigned by the manufacturer e.g. Mac Address. Data link layer makes use of physical address for sending frame within the network.
The logical address is assigned to host computers for the recognition of host outside the network. Network layer uses these logical address for routing packet over the networks. The logical address is also known as IP address.
Port address are used at the transport layer for sending a data to appropriate application layer protocol like FTP, HTTP, TELNET, etc.., there exist source port and destination port used to identify the application process on the source side and on the destination side.
Compare and contrast a circuit-switch versus a packet-switch network?
Circuit Switched Network
Used in telecommunications for carrying voice signals. E.g. Phone calls
The dedicated circuit has to be established before the call is made between the users.
This circuit stays alive as long as the call continues, later the circuit breaks.
Packet Switched Network
Used for carrying data in the form packets.
There exist no dedicated path for transmitting the packet to the destination. Generally, there exist some routing protocols which determine the best path to route the packet in the network
As the data is divided into chunks called packets, the packets are given sequence number by the upper layer protocol called transport layer. At the reception end, these packets are accumulated and arranged based on the sequence number.
For a Virtual Circuit compare SVC with a PVC?
PVC stands for Permanent virtual circuits. It defines the permanent/dedicated path between source and destination. If this path gets failed, then another backup path has to be created between the endpoints at extra cost.
SVC stands for switched virtual circuits. The link is established only when the data has to be transferred between the two end points and break down when the transmission is completed. When the link gets down, the alternate paths can be used for completing the transmission.
How is the ATM virtual connection identified?
There exist virtual path and virtual circuits in ATM. These are required to route the data between the source and destination and route is identified using two identifiers called as virtual circuit identifier(VCI) and virtual path identifier(VPI). VPI defines the virtual path whereas VCI defines the virtual circuits present in the virtual path.
ATM uses switching table for routing the cell between source and destination. The switching table contains the input VCI, VPI, incoming interface number and outputs VPI, VCI and outgoing interface number. The ATM maps the input VCI and VPI with the outgoing VPI, VCI, then replaces the header containing input VCI and VPI with output VCI and VPI and send the cell on the output interface.
Why are there no sequence numbers in Frame Relay?
Frame relay has no flow control mechanism nor retransmission policy once if the frame gets damaged. As there is no retransmission of frame concept, the frame relays don’t have any sequence numbers.
INTRODUCTION TO TELECOMMUNICATIONS
pg. 3y the transport layer. The network layer which lies between the data link layer and transport layer does not make any reliable communication because there is no error checking mechanism performed at this layer. So, there is a possibility for the data to get corrupted. In order to avoid the corrupted data transmission, the error checking is again performed at the transport layer.
Frame relay has no flow control mechanism nor retransmission policy once if the frame gets damaged. As there is no retransmission of frame concept, the frame relays don’t have any seque