Shulou(Shulou.com)06/03 Report--

Functions of the data link layer:

1. Establishment, maintenance and dismantling of data links

two。 Packaging, Transmission and synchronization of data frames

3. Error recovery of frames (parity)

4. Flow control-(QOS control priority, in case of data congestion, control priority diversion).

Ethernet MAC address:

The MAC address has 48 bits, that is, 48 binaries and 6 bytes.

Frame format of Ethernet:

Data transmission in segmented form: the data is segmented first, then transferred to the data pool one by one, and then arranged in the original order, and finally transmitted to the server.

How the switch works

Function: to achieve network interconnection, multiple computer communication.

Forwarding principle: 1. Initial state

2.MAC address learning

3. Broadcast unknown data frames

4. Receiver responds

5. Switch realizes unicast communication

To put it simply, computer A packages its own source MAC address and the destination MAC address of the B computer that it intends to communicate into data frames to send to the switch. the switch first remembers the source address of computer An and the A-side interface, and then it sends broadcasts to other devices (except computer A). At this point, computer B responds by packaging its source MAC address and the destination MAC address of computer A that it intends to communicate into a data frame and sending it to the switch. The switch will first remember the source address of computer B and the interface of computer B. because the MAC address of computer A has been remembered before, the switch transmits the data to computer A by unicast.

The mode of operation of the switch Ethernet interface:

1. Simplex: two data can only be transmitted in a single direction.

two。 Half-duplex: two data can be transmitted in both directions, but not at the same time.

3. Full-duplex: two pieces of data can be transmitted in both directions and simultaneously.

Switch Ethernet interface rate:

1. Negotiate when the interface is connected (either automatically or manually)

two。 If the negotiation fails, the normal communication will not be possible.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.