Cisco Device Learning

Four (five) types of passwords for Cisco devices:

1.Console Port Password

2.AUX Auxiliary Port Password

3.VTY Remote Telnet password

4.enable password/enable secert Privileged mode password

Password encryption for plaintext services: service password-encryption

Two-layer switch

MAC address learning + filtering and forwarding of data frames

+ Cycle Avoidance (STP)

STP action: To ensure that there is no loop in the network, when the two-layer switch discovers a loop in the network, the device blocks one or more ports, eliminating the loop.

STP work process: Sat algorithm that sends BPDUs periodically (Bridging Protocol data Unit)

Root bridge non-root bridge

A network is a broadcast domain with only one root bridge

A switch with the lowest bridge ID in a network is selected as the root bridge, and the other is a non-root bridge.

Bridge is the same as the MAC address, Mac Small is the root bridge.

Root port non-root port

Each non-root bridge can have only one root port, the port with the lowest path cost for the non-root bridge to the root bridge direction is the root port. If the path cost is the same, look at the port number of the switch, small priority.

Specify port: Each network segment has only one specified port, and the port on the network segment that reaches the root bridge has the lowest path cost value for the specified port, and the other is the non-specified port.

A network is a broadcast domain

A network segment is a conflict domain

VLAN and VTP protocol

Trunk protocol

Frame marker

IEEE 802.1Q

Dot 1 Q

Protocol core: Inserting a 4Byte-size tag tag after the original data field EtherType field 0x8100 represents the frame that this frame is a 802.1Q protocol tag. The VLAN ID indicates that this frame is the data frame of that VLAN.

Ils protocol, Cisco Private Protocol Data Link layer protocol Max 1522

Bytes

VTP advertises information on trunk links with multicast the default send period for 300s changes is sent immediately.

VTP pruning reduces broadcast, multicast, unicast transfer, reserved broadband

Cisco Device Learning