MAC/LLC and flow control applied to real world.

[wilder7bc]

Originally Posted by omgitseric

In the CCNA book, page 24(kindle), there are two paragraphs describing Media Access Control and Logical Link Control as they pertain to the Data Link Layer.

MAC lists "optional flow control" and LLC lists "can also provide flow control"

My question is in the real world application when I apply flow control to an interface, virtual or otherwise, which actual component is performing the flow control?

thoughts?
-e

I am not sure if I understand your question and I certainly am no expert on this but I will try to assist with atleast some information on this.

"Logical Link Control (LLC) handles communication between the network layer and the MAC sublayer. In general LLC provides a way to identify the protocol that is passed from the data link layer to the network layer. In this way the fields of the MAC submlayer are not populated with protocol type information as was the case in earlier Ethernet implementations.

The MAC sublayer has two primary responsibilities:

Data Encapsulation:

Includes frames assembly before transmission, frame parsing upon reception of a frame, data link layer MAC addressing, and error detection.

Media Access Control:

Because Ethernet is a shared media and all the devices can be transmitted at any time, media access is controlled by a method called Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

At the physical layer Ethernet specifies and implements encoding and decoding schemes that enable frame bits to be carried as signals across both UTP, copper cables and optical fiber cables."


The qoutes are not my words but some daily reading I do. not sure if any of that information helps you I find it to be pretty clear on what the MAC or LLC does but not sure if thats what you was after.

I will say that the CSMA/CD was a bit confusing to me as thats half duplex and NIC cards will run at full duplex or half so why would we ever run at Half but maybe this has some other meaning when put in context of the Media Access Control. However, other than that I think its straight forward.

Respectfully,

Brian