Computer Networks Why the primary and secondary synchronization points were introduced

Select B from your IP and mask arithmetic to know that your network ID is, your mask is 192, that is, 11000000, mask two network bits, the remaining 6 subnet bits, the 6th power of Equation 2 = 64, so 128 + 64-1 = 191, that is, the subnet where this IP is located is 128-191, so the broadcast address is 191

At a glance, you know it's B. 26 subnet, plus the IP you gave, the network number is 128; There are only 64-2 hosts, and the number of hosts A, C, and D is exceeded.

You are wrong, the answer to this question should be B, which is currently divided into 4 subnets, and this IP is in the third subnet. After adding points, you can answer in detail.

It is known that the sequence to be sent is 101011, the polynomial is generated as g(x)=x4+x+1, and the corresponding binary bit sequence is 10011, and the following binary division is carried out, the dividend is 101011 times 2 to the 5th power, that is, 1010110000, the divisor, 10011, and the remainder obtained is added to the 101011 to be followed by the bit sequence to be sent, and the result of my calculation is 100, that is, the bit sequence to be sent is 101011100.

And for you to check the correctness of the received codeword 100100011 is to use the received result to remove g(x), that is, to remove 10011 with 100100011, to see if the remainder is 0, if it is 0, it is correct, if it is not 0, it is incorrect, my answer is incorrect.

Hehe, this happened to be just learned, so I solved it for you!

Classification according to the medium of elm:

1) Cable network: the use of coaxial cable, twisted pair, and even the use of cable TV cable to connect the computer network, and the cable network through the "carrier" space to transmit information, need to use wires to realize.

2) Wireless network: use air as the transmission medium and electromagnetic waves as the carrier to transmit data. Wireless networks include: wireless, voice broadcasting networks, wireless television networks, microwave communication networks, and satellite communication networks.

3. Classification according to the topology of the network:

1) Star network: each site is connected to the center through a point-to-point link, which is characterized by the fact that it is easy to add new sites to the network, the security and priority of data are easy to control, and it is easy to realize network monitoring, but once the central node is faulty, it will cause the entire network to be paralyzed.

2), bus type network: all the sites in the network share a data channel, the bus type network installation is simple and convenient, the wire that needs to be laid is the shortest, the cost is low, the fault of a certain site generally does not affect the whole network, but the failure of the medium will cause the network to be paralyzed, the bus network security is low, the monitoring is more difficult, and the addition of new sites is not as easy as the star network.

3) Tree network: It is a combination of the above two networks.

4) Ring network: The ring network is easy to install and monitor, but the capacity is limited, and it is difficult to add new sites after the network is completed.

5) Mesh network: Mesh network is a comprehensive application based on the above-mentioned topological networks.

4. Classification according to communication mode:

1) Point-to-point transmission network: data is transmitted in computers or communication equipment in a point-to-point manner, and is connected by multiple paths between a pair of machines, and most of the large networks adopt this way.

200 kilometers is equal to 200,000 meters, 200,000 meters divided by the transmission rate of 200,000 meters per second is equal to 1 second, and 1 second is multiplied equally.

First, find the transmission rate of the cable p: 2 3*c

Data rate*200 km p

Here, it is necessary to analyze whether the question is the subnet mask of the newly added 25 subnets or the subnet mask of the Class B network.

Select B can only be used as the subnet mask for the 25 new subnets added in the next year, and cannot be used as the subnet mask for Class B networks.

After careful analysis, we are discussing what the subnet mask should be now, so the subnet mask of a Class B network that can accommodate 55 subnets (each network can accommodate a minimum of 600 hosts) should be asked, and D should be selected.

The subnet mask should be related to both the subnet number and the host number, 600 hosts should be 10 bits, a total of 55 subnets, should be 6 bits.

Subnet mask = network number + subnet number + host number, the network number is all 1, and the rest is all 0First of all, answer B must be wrong, answer B only has 10 0's, 22 1's, so there is only one subnet. So it's not true.

Whereas, the host number of a Class B network is at least 16 digits. Add 6 digits of subnet number, so the subnet number + host number has 16 + 6 bits, and the network number has 10 digits, and the subnet mask is: converted to decimal system.

It might be better to go to the Internet and ask about that category

VoIP technology, IPv6These are. The few hundred words you want are too general. It costs a few hundred words as soon as it comes up. How can anyone be so awesome. Let's find more information and take a look.