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+9 votes

Which of the following statements is TRUE about CSMA/CD

  1. IEEE 802.11 wireless LAN runs CSMA/CD protocol
  2. Ethernet is not based on CSMA/CD protocol
  3. CSMA/CD is not suitable for a high propagation delay network like satellite network
  4. There is no contention in a CSMA/CD network
asked in Computer Networks by (21.5k points) 139 177 177 | 1.1k views

IEEE Std 802.3, which defines all Ethernet variants, for historical reasons still bears the title "Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications" until 802.3-2008, which uses new name "IEEE Standard for Ethernet".

5 Answers

+14 votes
Best answer

CSMA/CD was used in early days,802.3 not in 802.11

There will be contention in this protocol.

Ethernet is based on csma/cd early in 1980s,
answered by (903 points)
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What is used in 802.11 ??
CSMA/CA is used in 802.11 (wireless lan)
+8 votes
The reason is in csma/Cd transmission time >=2*propagation delay so high prop. Time implies high transmission time so it's not efficient transmit a frame for a long time... So option c
answered by (13.6k points) 1 1
in which protocols, is the transmission time not => 2*propagation time ?
in CSMA/CA transmission time need not be  greater than or equal to 2*propagation time as unlike CSMA/CD , it does not require station to listen to channel while transmitting frames
+4 votes
Ieee 802.11 is the wifi wireless lan protocol and it uses csma/ ca collision avoidance ethernet is based on csma/cd. . and as in csma/cd. tt>= 2pd . that means we should have a lot of data in case we use it for satellite communication as satellite are very far away. so c is the answer.
answered by (15.2k points) 1 2 6
+4 votes
Efficiency of CSMA/CD= 1/(1+6.44a)=1/(1+6.44(Tp/Tt))

Tp=propagation time

Tp=transmission time

so if propagation time increases efficiency will decrease

So C is the Answer
answered by (6.6k points) 1 1
what do we mean by no contention in channel?

A type of network protocol that allows nodes to contend for network access. That is, two or more nodes may try to send messages across the networksimultaneously. The contention protocol defines what happens when this occurs. The most widely used contention protocol is CSMA/CD, used by Ethernet.

+3 votes

some info about "contention slot"

Contention Protocols resolve a collision after it occurs.These Protocols execute a collision resolution protocol after each collision

eg. Pure/Slotted Aloha, CSMA/CA(wireless), CSMA/CD(ethernet)

CSMA/CD  : -To detect a collision, in the worst case, it takes twice the maximum propagation delay of the medium

Ethernet requires a minimum packet size and restricts the maximum length of the medium

answered by (7.2k points) 1 1 1
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