Simulation experiment under eNSP simulator
1. Simulation experiment under eNSP simulator
Foreword:
For our first acquaintance with the network, eNSP is a very good software. It can simulate the situation of some network equipment, which is more conducive to our deepening understanding.
I won’t introduce some basic instructions here. Take a small model as an example:
as shown in the figure below, how to configure the router between PC1 and PC2 to achieve network intercommunication between PC1 and PC2, and implement one of them The line is disconnected and the other is automatically connected.
In our network topology diagram, we can see that PC1 wants to communicate with PC2, and it needs to be addressed through hops between routers. There are two lines.
A.PC1–AR1–AR2–AR4–PC2 (main)
B.PC1–AR1–AR3–AR4–PC2 (standby)
Here we regard the first line as the main line and the second line as the backup network (here The proper term is called floating routing)
Before we start to simulate the line, we need to determine the interface IP address of each routing, we can mark the IP address on the map
Now that the preparations are complete, let's start the simulation experiment:
1. Set the IP address of each port of each router.
Here we configure the router of R1 as shown in the figure below:
we turn on all the devices and open all the CLIs, find the box of R1 to configure.
Here ### means that it is being read for a while. After entering, the default name is Huawei. We will modify it. As shown in the figure below, we will change the device name to R1.
After we set the name of the device, we need to start the configuration of the network interface. The part noted in the red part of the figure below.
(Huawei eNSP's command input supports Lenovo abbreviations. You can associate a part of the command by pressing and holding Tab. If you don’t know what command to enter, you can enter it after a part of the command? A pop-up reminder of what related commands are available)
Here we have completed the IP configuration for each network interface on the R1 router. R2, R3, and R4 are all set in accordance with R1, so I won't go into details here.
2. After we have completed the interface settings of each switch. We began to analyze how the route should jump to PC2.
We aimed at route A: A. PC1–AR1–AR2–AR4–PC2 (main)
The direct route of PC1 is AR1, and data packets need to skip AR2 and AR4 routers. To communicate with PC2, so we need to configure two static routes of AR1, one is between AR2–AR4 and AR4–PC2, so we enter the static route address as shown in the figure below.
When the packet reaches the AR2 route, AR1 and AR4 are both AR2 is directly connected, so when the data packet is transmitted to the next network segment, it needs to be transmitted to PC2 through R4, so only the network segment connected between AR4 and PC2 needs to be hopped. Of course, the data packets here need to be round-tripped, so we also need to configure the transmission to PC1 after PC2 arrives at AR2. We need to skip AR1 and transfer to PC1, so we also need to use 20.0.0.1 as the jump point to PC1 and AR1. The connected network segment jumps.
Therefore, the static routes we need to configure for AR2 are the 10.0.0.0 network segment and the 192.168.1.0 network segment. As shown in the figure below,
when the data packet reaches AR4, the data packet can be directly sent to the directly connected PC2. When the data packet needs to be sent back to PC1, it is found that if PC2 wants to reach PC1, it needs to pass through AR2 and AR1 routers. To connect to PC1, you need to jump to both ends of the network segment, that is, the 20.0.0.0 network segment and the 192.168.1.0 network segment, so you can directly configure the two static routes of AR4. As shown in the figure below
, after the routers are all configured, we Configure corresponding PC hosts that need to communicate with each other. As shown in PC2 below
PC1 is also configured, and then PC1 sends data packets to PC2 to check whether the two PCs are smooth, that is, PC1 pings the network address of PC2 as shown in the figure below.
We find that "Request timeout" is always jumping here, so we use tracert + ip address To query the specific data packet where the problem occurred, as shown
in the figure below, we found that the data packet sent by PC1 was broken after passing 20 40, indicating that the data was broken when it reached AR4, so we went to check the configuration of AR4. But here I checked all the routers many times and still did not find the problem. The address and static configuration of each route are all right, until after a long time I did not pay attention to the wrong point and opened the PC2 settings and found that I was before The data configured for PC2 is not saved, that is, no application is clicked, so the data can only be transferred to AR4 and cannot be transferred, let alone transfer from PC2 to PC1. Here tells us that you need to set it at hand and save it at hand, otherwise it will be difficult to find errors. (The author spent a few hours here, configuring the configuration of each router several times, but still did not find it, so please remember to save the TAT... or if you encounter problems)
After I configure the IP of PC 2 and then click on the command line of PC2 to ping the IP address of PC1 as shown in the figure below, the first line shows timeout, there is no need to panic here, because the IP address just configured is the first time Communication, this will happen, usually just a few.
When PC2PING connects to PC1, we also need to go to PC1 to PING, and
we find that the same is true for PC2 , which means that the back and forth from PC1 to PC2 is completed, that is, the first line configuration is completed.
Later, we will configure the B line as a floating route (standby). Here we can know that the configuration principle is the same as that of the A line. I won't repeat it here. You can configure it slowly according to the A line.
One of the more important points is that the priority setting is
known by the topology map. The routes of line A and line B are the same. If the priority is not set, lines A and B are at the same level (we tried both at the same time). No priority is set for each point, and data packets will only go to the line that is connected first by default.) You
only need to add the priority configuration when setting up the static route.
For route B, the priority only needs to be set at both ends of AR1 and AR4. As shown in the figure below for AR1,
when the priorities of AR1 and AR4 are set, that is, the main path and floating (main/backup) route from PC1 to PC2. All set up, here we must save each routing interface "save" as shown in the figure below, here you need to enter the user view to perform SAVE and enter a Y to close it. (I didn’t know at the beginning, I thought it would be saved automatically after the configuration, so I closed it directly, so all the configurations were cleared. Later I learned that SAVE is required for each configuration. Please develop a good habit of SAVE.)
2. Priority test of eNSP floating route (standby)
Now let's experiment with the performance of floating routing.
Before testing, we need to save all routing equipment! ! ! ! ! ! !
Before disconnecting, let's take a look at how PC1 to PC2 take route A.
Using the tracert command, we can see that the AR2 route is indeed passed.
Now we disconnect AR2, execute the tracert command again, and see how the data packet goes.
When we disconnect the AR2, the data packet does go through the B line, which means that our AB line does have a disaster tolerance function.
The author here restarts AR2 and disconnects AR3, and it can be connected. Here, our AB line is configured.
Here is an introduction. If the priority is not set on the same route, the addressing will not be forwarded according to the priority, but will only be sent according to the order of connection. For example, if the route is not set to the priority here. For AR1, if the A line is connected first, then all will go from the A line, and the B line will not be used until the A line fails.
Experiment here to see if priority works.
The priority we set before,
according to the previous, the data packet has been sent on the B line, because the B line has a lower priority than the A line, so here if we restore the A line again, the route of the data packet should be automatically transferred to B A, so you can verify whether the priority setting is useful.
First, we first restore the A line (that is, turn on AR2)
and then reopen the command line of PC1. We enter tracert to query the line of the data packet. According to the change of the transmission node, we find that the line is automatically switched to line A, which proves that we have set The priority of the floating (backup) route is as expected! ! !
3. Summary of related errors
Well, the above is the introduction to the eNSP simulation experiment by hand. Next, I will record some summary of the errors in the use process.
1. When editing the interface address, edit the wrong gateway for each interface address, resulting in an error, and then unable to ping the client.
2. After all routing configuration is completed, please remember to SAVE. Once you close the small window, all configurations will be automatically cleared and gone! It's all gone! ! It's all gone! ! ! Say it three times. . .
3. After the terminal device is configured, remember to click the application, otherwise it will not work.
4. For the problem of configuring static ip. We can understand that any network segment to be hopped is a non-directly connected network segment that must be routed through the current route. All need to be achieved by hopping network segments, then we need to set up static routes for that segment.
5. Remember to enter undo shoutdown (un sh) for the interface that has been configured, otherwise the network interface of the router is not opened. You can use the display interface brief command to check whether it is open. If the corresponding time is down, it is closed.
5. Simulate eNSP thinking:
(1) First determine the network topology diagram
(2) Connect the direct interfaces of each device, and determine the IP address
(3) Enter each route in the topology diagram to configure the interface IP address
(4) Enter each Routing settings for each static route, and the data return address
(5) through the terminal PING command or tracert command to check, if there is a problem, go to each point to check
(6) If there is no problem, remember to Save! ! !
Feeling: For us beginners, we don’t need to panic when we encounter inexplicable problems. We are not familiar with it at the beginning. It is normal for problems. The most important thing is to believe that we can solve them and take time. Check it step by step and you can definitely find your own problems. Come on, comrades! ~