Shulou(Shulou.com)06/01 Report--

I. functions of the data link layer

Establishment, maintenance and removal of data links, packaging, transmission and synchronization of frames

Frame error recovery, flow control

Second, the development history of Ethernet

Ethernet works at the data link layer

1. X-WIRE XEROX 2.94m Experimental Ethernet

2. DIX 10 megabit Ethernet

3. IEEE802.3 10 megabit Ethernet standard

4. Gigabit Ethernet 100 / 1000 megabit Ethernet

3. MAC address of Ethernet

An Ethernet address is used to identify an independent device or group of devices on an Ethernet. The length of the MAC address is 48 bits (6 bytes). The first 24 bits represent the Ethernet number. The 8th bit of the MAC address is 0 to indicate that the MAC address is a unicast address, 1 indicates a multicast address, and 48 bits are 1 to indicate a broadcast address.

Note: the address of a physical network card must be a unicast address, that is, bit 8 must be 0, and the multicast address must be a logical address.

IV. Ethernet format

Fifth, the working principle of the switch

Initial state

Learn according to the source MAC address

The port except the source port broadcasts unknown data frames

The recipient responds

Switch realizes unicast communication

Update: aging time 300s-when the MAC address of the corresponding port of the switch changes

VI. Duplex mode of switch port

Simplex: data can only be transmitted in a single direction between two data stations

Half-duplex: two-way communication between two data stations, but not at the same time

Full-duplex: data can be transmitted in both directions and at the same time between two data stations.

7. The working mode of the switch

The mode of operation of the CISCO switch:

1. SWITCH > user mode

2. SWITHC > enable enters SWITCH # privilege mode

3. SWITCH # configure terminal enters SWITCH (config) # global mode

4. SWITCH (config) # interface fasterthernet 0swap 1 enters SWITCH (config-if) # interface mode

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