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

HCNA Ethernet Foundation

-Luosir

Several common physical transmission media are briefly introduced.

> 1. Twisted pair (Twisted Pair): twisted pair of 8 different colored wires are twisted into four pairs, and the two ends are made up of the crystal head of RJ-45. Two pairs of wires are twisted together to counteract the magnetic field generated by each other to increase the distance of transmission. The maximum transmission distance of ordinary twisted pair is 100m. In order to increase the transmission distance, it is generally necessary to increase the transmission distance through devices such as intermediate access switches or hubs. There are generally two general standards.

That is, 56-8A and 56-8B

56-8B: orange-white-orange, green-white-blue, blue-white-green, brown-white-brown (to make it easier to remember, I divided these 12 words into four groups. The 56-8B standard is mostly used in practical use.

56-8A: green white green, orange white blue, blue white orange, brown white brown. (it is rarely used and will not be introduced here.)

56-8B has two different wire sequences: straight-through line and cross line (PC and Router belong to the same network device)

Straight line: used to connect different network devices. (e. G. PC-Switch,PC-Hub;Router- Switch,Router- Hub)

Crossover wire: used to connect the same network devices. (e. G. Switch-Switch,Hub-Hub,PC-PC,Switch-Hub,Router-PC,Router-Router)

> 2. Reversal line: used to connect from the host to the router console serial communication (com) port. If you need to connect the computer for CONSOLE control, you need to convert this end of the connection computer into a 9-pin serial port mother head; while there is no 9-pin serial port male head on some notebook computers, then you need to transfer the 9-pin serial port mother head to the USB port adapter, which is transferred to the USB port, that is, the debugging equipment is prompted by the COM port.

> 3. Optical fiber: a waveguide made of glass and plastic that transmits light from one end to the other. it is composed of a core and a cladding, which is used to transmit light, and the cladding limits light in the core. Optical fiber is mainly divided into single-mode and multi-mode. Single-mode optical fiber can transmit optical signals at high speed, while multimode optical fiber can transmit multi-channel light. Therefore, the cost of single-mode optical fiber is much more expensive.

2.LAB:

Configuration of AR1:

System-view / / enter the system view

[Huawei] sysname AR1 / / device naming

[AR1] int GigabitEthernet 0Universe 1 / / enter the interface

[AR1-GigabitEthernet0/0/1] ip address 10.1.1.1 24 / / configure IP address

Configuration of SW1:

System-view / / enter the system view

[Huawei] sysname SW1 / / device naming

[AR1] interface Vlanif 1 / / enter the vlanif 1 interface

[AR1-Vlanif1] ip address 10.1.1.254 24 / / configure IP address

Layer 2 switch, only one management IP can be configured

Test:

[SW1] ping-a 10.1.1.254 10.1.1.1 / / ping with the original address can prevent the default ping from starting with the interface ping, but it doesn't matter here.

PING 10.1.1.1: 56 data bytes, press CTRL_C to break

Reply from 10.1.1.1: bytes=56 Sequence=1 ttl=255 time=10 ms

Reply from 10.1.1.1: bytes=56 Sequence=2 ttl=255 time=50 ms

Reply from 10.1.1.1: bytes=56 Sequence=3 ttl=255 time=40 ms

Reply from 10.1.1.1: bytes=56 Sequence=4 ttl=255 time=10 ms

Reply from 10.1.1.1: bytes=56 Sequence=5 ttl=255 time=50 ms

-10.1.1.1 ping statistics-

5 packet (s) transmitted

5 packet (s) received

0.005% packet loss

Round-trip min/avg/max = 10-32-50 ms

Test connectivity complete!

Data message format for requests and replies to Packets:ICMP messages:

0 7 15 31

Type

Code

Checksum

Identifier

Sequence Number

Data... ..

Summary & configuration ideas

It is better to pass the eye a thousand times than the hand once.

For layer 2 switches, in many cases, only one management IP can be configured for management.

When configuring IP addresses, Huawei and Huasan's devices can mask the number of bits directly behind them, while Cisco's devices need to be fully masked.

Configuration ideas:

> 1. First of all, we need to name the device before configuration, which is to ensure that it is easy to distinguish when configuring devices in the future, and can be distinguished efficiently when there are many devices, which should form a habit.

> 2. After we try to enter the system, we have to configure what and what to enter, for example, configure the IP address, enter the interface, then configure the IP address, configure the VLAN, create the VLAN before we have the configuration VLAN permission, and so on. This is a general configuration idea and can be extended to other configuration modes.

> 3. When we complete the configuration, we can use ping (based on icmp protocol) to do the test, but often we can only ping after the test is the most basic step, very often we should pay attention to its principle, ping is reasonable, ping does not understand the reason, in order to do so, can be quickly improved. Don't be fooled by appearances.

> 4. Try to use the open source software Wireshark to grab data packets for analysis to deepen the understanding of the protocol.

ITop_Luo

October 8, 2015

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