Linux Network application Programming hub (Packet tracer emulation)

Packet Tracer Introductory One, hub overview

The received signal is amplified by reproducing and shaping to enlarge the transmission distance of the network, and all nodes are concentrated on the node which is centered on it.

Work at the bottom (physical layer) of the OSI (open System Interconnect Reference Model).

II, Hub classification

Passive hubs: No processing of signals, no expansion of the transmission distance to the media. The hub broadcasts the signal it receives to all devices connected to it.

Active hubs: The biggest difference from passive hubs is the ability to shape and amplify signals, which can increase the distance between two devices.

Smart hubs: With both of these, network management and routing capabilities are also available.

Three, Pc+hub simulation

Run packet Tracer, in the bottom right corner of the popup interface, click Terminal Equipment (in the figure with a mark), then the next device class will appear the PC, server, printer, phone, selected PC (figure with B mark) and drag it to the work area (drag two PC to the workspace).

Then click on the hub in the lower right corner (with the C tag in the hubs chart), and the next device class will also have a variety of hubs, so let's practice selecting the first one (with the D mark in the figure) and dragging it to the workspace.

At this time our equipment has been selected, we will use the line to connect the various devices: Click the line icon in the lower right corner (shown with the e Mark), the next device class will appear a lot of lines, click the first line (the F mark in the figure)

Move the mouse to the workspace the mouse will become "thread", the mouse click on any device of the workspace then the mouse will lead to a line, and then click on another device, the two devices will be connected together, repeat such steps to complete the network topology in the diagram.

The rest of the work is to configure the PC, hub parameters to make it work.

To PC1 Ping PC2, you should let PC1 and PC2 in the same network segment, then you will configure PC1 and PC2 network parameters: According to the instructions in the diagram, the diagram is to PC1 settings, if the PC2 network settings need to change the picture 3:ip Adress is 192.168.1.XX, here XX means not the same as the other host IP on the line, Subbet Mask does not become 255.255.255.0

After configuring the network parameters, our job is to ping PC2 with PC1: operation

When we hit 2, there will be a cmd terminal, enter ping 192.168.1.2 in this terminal, where "192.168.1.2" with your PC2 IP, (real-time mode) operation results are as follows:

(emulation mode) operation Result: note that before the cmd terminal ping 192.168.1.2, it is necessary to adjust the above real-time mode to emulation mode in the main interface:

At this point to the cmd Terminal ping 192.168.1.2, note that the results are now not seen, because we are running in emulation mode, PC1 ICMP will not like the real-time mode of the packet to PC2 immediately, because it requires us to step-by-step debugging.

During our debugging, the ICMP request packet will be PC1-->HUB-->PC2, and then the PC2 ICMP response packet PC2---->hub---->PC1, such that a ping is completed.

Four, knowledge expansion

in the above simulation mode debugging, we can understand the ICMP packet from one device to another through single-step debugging, if we want to understand how the packet has changed in this process, we need to do the following: Through this graph we can see that the packet of the ping command is the Ethernet header, IP header,  The ICMP packets are composed. Transferred from: http://blog.csdn.net/lianghe_work/article/details/44570695

Linux Network application Programming hub (Packet tracer emulation)