Experiment and instructions have been uploaded on my lot: https://github.com/Icarusintheworld/ComputerNework_guidebook.git experiment: 5/24/2017

1. Preparation for the experiment Each member reviewed the previous experiment notes, paying special attention to the configuration purpose, use conditions and command syntax of various configuration commands.

2. Division of labor and task arrangement

Before and throughout the experiment, the team members encouraged each other and maintained a positive attitude that no matter how bad the test was, it would be better than the mathematical statistics test. ↖ (^. ^) ↗

3. Analysis of experimental process and difficulties

  1. In previous experiments, we found that the first port of the second layer-2 switch in cabinet 58 was opposite to the third port. We paid special attention to this problem during the connection of this experiment.

  2. In simple subnet partitioning experiments, the first step is very important for IP and subsequent configuration. 112(10) = 01110000(2), so we have 12(4+ 8 of the last byte) bits to allocate. During the calculation, IP addresses are assigned to the four departments in the order of the number of departments. (There should be a map of the IP result we calculated, but we lost that piece of paper.)

  3. In the simple subnet division experiment, we use a PC to simulate a department, and select an IP address randomly from the calculated IP address segment of each department to set to the PC.

  4. In the simple subnet division experiment, when the VLAN IP address is configured on the Layer 3 switch, the VLAN IP address is set to the gateway address of the corresponding department. The router configuration results are as follows:

  5. In the experiment of subnet division network, we felt strange when calculating IP. Because 20(10) = 00010100(2), and 10 bits is definitely not enough to allocate. So we choose to look at the second-to-last 1, allocate the next 12 bits, but remove the 2^10 IP addresses before 20.0.

In the calculation, we still assign IP addresses to the four departments in the order of the number of departments. (There should be a map of the IP result we calculated, but we lost that piece of paper, too.)

  1. In the comprehensive networking experiment of subnet division, our team and 54 cabinet team worked in coordination. They acted as the right half of the figure and we acted as the left half of the figure. The main problem is the cable connection between two groups of cabinets. Four ports on each group of cabinets are marked as the opposite cabinet. 58 Four marks on the cabinet The ports on the cabinet 54 are connected to the ports on the cabinet 58. Therefore, the router in cabinet 58 is connected to a port in cabinet 54, and the router in cabinet 54 is connected to the same port in cabinet 58.

Analysis and summary of experimental results

  1. In the simple subnet partitioning experiment, the Trunk interface is used for cascading between switches. By sacrificing the number of ports, the Trunk interface provides bundled high bandwidth for the data exchange between switches, which improves the network speed, breaks through the network bottleneck, and greatly improves the network performance. If no TRUNK is configured, the ping succeeds.

  2. In the networking experiment of subnet division, the loopback in the figure is the local loopback interface (or address), also known as the loopback address. This type of interface is the most widely used virtual interface and is used by almost every router. It is commonly used in the following ways: A) As the management Address of a Router After the network planning, the system administrator creates a loopback interface for each router and assigns an IP address to the interface as the management address. The administrator uses the IP address to log in to the router remotely (Telnet). The address actually performs a function similar to the device name. B) Use the interface ADDRESS as the Router ID of DYNAMIC routing protocols OSPF and BGP During OSPF and BGP running, a router ID must be specified as the unique IDENTIFIER of the router and must be unique in the entire AS. Since the Router ID is a 32-bit unsigned integer, this is much like an IP address. Therefore, the router ID of a router is usually specified to be the same as the address of an interface on the device. The IP address of the loopback interface is usually regarded as the router id, so it is the best choice for the router ID. C) Use the address of the interface as the source ADDRESS for BGP to establish TCP connections. In BGP, two ROUTERS running BGP establish neighbor relationships through TCP connections. When configuring a neighbor, you usually specify a loopback interface as the source address for establishing TCP connections.

  3. In the network experiment of subnet division, PCa, PCb and PCc of our group could be pinged through, but PCd could not be pinged through. After discussion and analysis, we think we may be wrong in the following two areas

We have tried to change the IP address of the configured VLAN, but the ping fails. We also tried to configure static routes according to the steps in Experiment 10, but the configuration failed all the time (the configuration command reported an error, or the configuration command did not report an error and could be executed, but the static route was not displayed in the routing table after using the display IP routing-table command). The configuration is shown as follows:

We even tried to recompute the IP address, reboot the whole thing and reconfigure it, but it still didn’t work. For reasons of time, we decided to drop the question.

  1. In the comprehensive networking experiment of subnet division, our group and 54 cabinet group were able to ping through PCS in their respective groups. Some configuration commands are as follows:

  2. In the comprehensive networking experiment of subnet division, our group could not ping through the 54 cabinet group. After discussion and analysis, we decided that we had made a mistake in the configuration of static routes between the two groups. Therefore, we tried to set the static route, but the configuration command always received an error message, as shown in the following figure:

It was metaphysics, I guess, and we ended up giving up.