• Thread starter Wilson Velásquez
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Wilson Velásquez

Hello, i´m finishing the university right now and i want to know what is the relation between TCP/IP and CSMA/CD. Thank´s soo much.
The media access control protocol for Ethernet LANs is called CSMA/CD (Carrier Sense Media Access/Collision Detection)

Ethernet uses Shared bus Topology, where multiple computers tx/rx frames. Before txmiting a frame, the computer wishing to transmit a frame has to check for availability of carrier.
IF(No Carrier is detected) {it is safe to transmit; } else {wait for a random time duration and try again;}
This scheme is known as CSMA-Carrier Sense Multiple Access
Now if two or more computers find the bus to be idle, then both/all can start txmiting frames. This results in COLLISION.
So every sender should checkif any other sender has transmitted....If the sender finds that someone else has transmitted, then it STOPS transmitting. then again...test...
IF(No Carrier is detected) {
its safe to transmit; } else {
wait for a random time duration and try again; }
This is Known as CD (Collision Detection)


The TCP/IP model has the following Layers:
layer 5. Application Layer
layer 4. Transport Layer
layer 3. Internet Layer
layer 2+1. Network Layer

The layers 2 and 1 are a combination of [Data Link Layer] and [Physical Layer]

IN the layers shown above, The DATA LINK LAYER is responsible for MAC(Medium Access Control). This is the place where CSMA/CD is taken care of.

Ethernet exists at the network access layer - its hardware operates at the physical layer and its medium access control method (CSMA/CD) operates at the datalink layer.

Hope this Carries SENSE :)


CSMA/CD is the fundamental of EThernet (review OSI Model, important info on CISCO webpage). Ethernet 802.3 runs in Layer 2 of OSI model, whereas IP do it on layer 3 (Network) and TCP does it on Layer 4.

So, if you are using Ethernet as a Media of connection, it will have relation, in order to reach layer#3 of OSI, Packets (datagrams) will have to be treated by this algorithm on layer 2 of OSI.


Jake Brodsky

Ugh. I hope your degree is not engineering or computer science. If this is an example of what universities are not teaching, we're in BIG trouble...

TCP/IP = Transmission Control Protocol/Internet Protocol

CSMA/CD = Carrier Sense Multiple Access/Collision Detection

Basically, CSMA/CD is a physical layer behavior description for a Local Area Network (LAN) and TCP/IP is a protocol you could put on a LAN, a Wide Area Network, or the internet. They are related only because they're commonly found together (like fish and chips). However they address completely different layers of the OSI network model.

I would discuss this further, but this is the wrong forum for that sort of thing and frankly, I think you ought to look it up in your textbooks next time...