Which channel is better for stop and wait protocol?
Stop & Wait Protocol performs better for LANs than WANs because the efficiency of the protocol is inversely proportional to the distance between the sender & receiver node and as we all know that the distance is less in LANs as compared to WANs.
What is the utilization percentage of the link?
What is the utilization percentage of the link in Example 1 if the link uses Go- Back-N ARQ with a 15-frame sequence? The bandwidth-delay product is still 20,000. The system can send up to 15 frames or 15,000 bits during a round trip. This means the utilization is 15,000/20,000, or 75 percent.
What is the utilization of the link?
For each link, utilization is defined as the amount of traffic traversing it divided by the link capacity. Since modern networks consist of many links, the (weighted) average of the link utilization is used as a single number representing network utilization.
How is LAN utilization calculated?
On Windows, it is calculated by dividing the Network Interface(*)\Bytes/sec performance counter by the Current Bandwidth and multiplying the result by 400.
What is the utilization percentage of the link in que 2 if we have a protocol that can send up to 15 frames before stopping and worrying about the acknowledgments?
system can send up to 15 frames or 15,000 bits during a round trip. This means the utilization is 15,000/20,000, or 75 percent.
Why do data link layer protocols need framing?
Framing is a function of the data link layer. It provides a way for a sender to transmit a set of bits that are meaningful to the receiver. Ethernet, token ring, frame relay, and other data link layer technologies have their own frame structures.
What are the three types of frames used in HDLC protocol?
These three different classes of frames used in HDLC are given below.
- I-frame : I-frame stands for Information frames. This frame is generally used for transporting user data from network layer.
- S-frame : S-frame stands for Supervisory frames.
- U-frame : U-frame stands for Unnumbered frames.
How many retransmissions takes place in GBN ARQ if 1 packet is lost?
According to question, every 5th packet gets lost. So, packet-7 gets lost and when time out occurs, sender retransmits packet-7 and the following packets.
Why go back n and selective repeat was invented?
In Go-Back-N Protocol, if the sent frame are find suspected then all the frames are re-transmitted from the lost packet to the last packet transmitted. In selective Repeat protocol, only those frames are re-transmitted which are found suspected. Receiver window size of selective Repeat protocol is N.
Is TCP go back n?
In general, TCP’s congestion control can be described as a combination/hybrid of GBN and Selective Repeat. TCP is similar to selective repeat because, when packets are lost due to congestion, the protocols do not require the sender to retransmit EVERY unACK’d packet sent by the sender.
In what way selective repeat is better than go back N ARQ technique?
In Go-Back-N if a sent frame is found suspected or damaged then all the frames are retransmitted till the last packet. In Selective Repeat, only the suspected or damaged frames are retransmitted. Go-Back-N is easier to implement. In Selective Repeat, receiver window needs to sort the frames.
What are the pros and cons of selective repeat ARQ?
- Go-back-N: pro: single timer, simple con: not efficient, waste bandwidth when a packet is lost/broken.
- Selective repeat: pro: efficient, only lost/broken packets need retransmission con: complicated with multiple timers, receiver needs a buffer to buffer out-of-order packets.
What is the use of selective repeat protocol?
Selective repeat protocol, also called Selective Repeat ARQ (Automatic Repeat reQuest), is a data link layer protocol that uses sliding window method for reliable delivery of data frames. Here, only the erroneous or lost frames are retransmitted, while the good frames are received and buffered.
Why Go Back N ARQ is not as efficient as selective repeat ARQ?
The basic difference between go-back-n protocol and selective repeat protocol is that the “go-back-n protocol” retransmits all the frames that lie after the frame which is damaged or lost. The “selective repeat protocol” retransmits only that frame which is damaged or lost.
Which is better selective repeat or go back n?
Go back N is better than Selective Repeat in terms of CPU usage. Go back N is better than Selective Repeat in terms of implementation difficulty. Sending cumulative acknowledgements reduces the traffic in the network but if it is lost, then the ACKs for all the corresponding packets are lost.
Which ARQ mechanism deals with transmission of only damaged or lost frames?
Go-Back-n ARQ: In Go-Back-N ARQ protocol, if one frame is lost or damaged, then it retransmits all the frames after which it does not receive the positive ACK.
What are ARQ protocols?
Automatic Repeat ReQuest (ARQ) is a group of error – control protocols for transmission of data over noisy or unreliable communication network. These protocols reside in the Data Link Layer and in the Transport Layer of the OSI (Open Systems Interconnection) reference model.
What are the two types of ARQ?
The types of ARQ protocols include Stop-and-wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ/Selective Reject ARQ. All three protocols usually use some form of sliding window protocol to help the transmitter determine which (if any) packets need to be retransmitted.
What is HARQ process?
HARQ stands for Hybrid Automatic Repeat Request. HARQ = ARQ + FEC (Forward Error Correction)/Soft Combining. ARQ refers to Automatic Repeat Request i.e. if sender doesn’t receive Acknowledgement (ACK) before timeout, the receiver discards the bad packet and sender shall re-transmits the packet.
What are three popular ARQ mechanisms?
Three main types of the ARQ are the Stop-and-wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ.
How ARQ is used in error detection?
In an ARQ scheme, the receiver uses an error detection code, typically a Cyclic Redundancy Check (CRC), to detect whether the received packet is in error. If an error is detected, the receiver discards the packet and sends a negative acknowledgement to the transmitter, and requests a re-transmission.
How does the ARQ work?
Automatic repeat request (ARQ) is a protocol for error control in data transmission. When the receiver detects an error in a packet, it automatically requests the transmitter to resend the packet. ARQ is sometimes used with Global System for Mobile (GSM) communication to guarantee data integrity.
Which is an efficient ARQ protocols?
This protocol is more efficient than Stop and wait ARQ as there is no waiting time. Selective Repeat ARQ/Selective Reject ARQ: Unlike, Go back-N protocol this does not send a packet multiple times.
Which sliding window ARQ is more popular?
Selective Repeat ARQ But if there is a lot of error in the frame, lots of bandwidth loss in sending the frames again. So, we use the Selective Repeat ARQ protocol. In this protocol, the size of the sender window is always equal to the size of the receiver window. The size of the sliding window is always greater than 1.
Which ARQ flow control protocol is used by TCP?
A sliding window protocol is a feature of packet-based data transmission protocols. Sliding window protocols are used where reliable in-order delivery of packets is required, such as in the data link layer (OSI layer 2) as well as in the Transmission Control Protocol (TCP).
What are the three protocols used for noisy channels?
Noisy Channels Protocol
- Stop-and-Wait Automatic Repeat Request. The Stop-and-Wait Automatic Repeat Request (Stop-and-Wait ARQ), adds a simple error control mechanism to the Stop-and-Wait Protocol.
- Go-Back-N Automatic Repeat Request.
- Selective Repeat Automatic Repeat Request.