100km/(2 *108m/s) = 0.5ms, so the propagation delay is 100 * 0.5ms = 50ms.
In order to make the transmission delay equal to the propagation delay,100/c = 0.5 ms.
Therefore, the transmission delay is about 2000kbps.
For the second question: the active tree takes the multicast source as the root of the active tree, the branches of the active tree form the distribution tree of the network reaching the destination address, and the active tree runs through the network with the shortest path.
* * * Enjoy Tree takes one of some optional multicast routes in the multicast source as the common * * * root of the * * * Enjoy Tree, that is, the meeting point.
Question 3: I haven't considered it, mainly because there is no information in this regard.
For the fourth question: TCP serial number is 32bit.
Then, when the number of byte stream transmissions is 2 32 bytes, the TCP sequence number wraps around.
2 32 bytes = 4GB of data
40Gbps pipeline =5GB pipeline
The wrap-around time is 4GB/5GB=0.8 seconds.
So there is a wrap in 0.8 seconds.
Using extended TCP option timescale to solve the wrap problem
If the clock frequency of the time scale is 1KHZ, the clock ticks 10 3 times per second.
For the 32-bit expansion option
A * * * has 2 32 numbers for the clock to tick.
It takes 2 32/10 3 seconds.
A simple estimate is 2 32/2 10 second (2 10 = 1024, about 1000).
It's about 4 * 10 6 seconds, once every 46 days.
For the fifth question: no.
Network congestion refers to the congestion caused by the data flow exceeding the capacity of the server or line in unit time. This solution can improve the processing capacity and speed of the server and increase the bandwidth.
Network resources are a general term. Information, data, hardware and software on the network can all be called network resources, which have nothing to do with network congestion.
As for the sixth question, there are several reasons why UDP and TCP are different:
1. Lowest cost.
2. Start sending data at the maximum transmission rate.
3. The request is not repeated, so there is no retransmission (the loss of a single packet is not important in real-time applications).
4. The processing time is short. No buffer is needed.
Unlike TCP, UDP does not provide reliable mechanism, flow control and error recovery functions for IP protocol. Because UDP is relatively simple, the UDP header contains fewer bytes and consumes less load than TCP.
For the seventh question: digital signature can be used to verify the authenticity and integrity of documents. Digital signature uses powerful encryption technology and public key infrastructure to better ensure the authenticity, integrity and identifiability of documents.
For the eighth question: Layer 2 switching technology+Layer 3 forwarding technology. It solves the problem that the subnet in the network segment must be managed by the router after the network segment is divided in the local area network, and solves the network bottleneck problem caused by the slow speed and complexity of the traditional router.
The traditional switching technology works in the second layer of OSI network standard model-data link layer, while the three-layer switching technology realizes the high-speed forwarding of data packets in the third layer of network model.
The principle is as follows: suppose two sites A and B using IP protocol communicate through a three-layer switch. At the beginning of transmission, the sending site A compares its IP address with the IP address of Miley Miley to determine whether Miley Miley is in the same subnet with itself. If the target station B and the transmitting station A are in the same subnet, layer 2 forwarding is performed. If the two sites are not in the same subnet, if the sending station A wants to communicate with the destination station B, the sending station A will send an ARP (Address Resolution) packet to the "default gateway", and the IP address of the "default gateway" is actually the three-layer switching module of the three-layer switch. When the sending station A broadcasts an ARP request to the IP address of the "default gateway", if the three-layer switching module already knows the MAC address of Miley Miley in the previous communication process, it will reply the MAC address of B to the sending station A. Otherwise, the three-layer switching module broadcasts an ARP request to Miley Miley according to the routing information, and Miley Miley will reply its MAC address to the three-layer switching module after receiving this ARP request, and the three-layer switching module will save this address and reply to the sending station A, and at the same time, it will beep. All data packets sent from A to B are handed over to Layer 2 for processing, and information can be exchanged at high speed. Because the routing process only needs three layers of processing, and most of the data is forwarded through layer 2 switching, the speed of the layer 3 switch is very fast, close to layer 2 switches, and the price is much lower than that of the same router.
For the ninth question:
P2P: It means that while you download it yourself, your computer will continue to upload it to the host. This download method, the more people, the faster the speed, but the disadvantage is that it will damage your hard disk (you have to write and read at the same time), occupy more memory and affect the speed of the whole machine!
C/S structure software (that is, client/server mode): it is divided into two layers: client and server. The client is not an input and output device without computing power, but has certain data processing and data storage capabilities. By reasonably distributing the calculation and data of application software at both ends of the client and the server, the network traffic and the calculation amount of the server can be effectively reduced. Due to the limitation of the number of server connections and data flow, the software with this structure is suitable for LAN with a small number of users.
B/S (browser/server mode) is an improvement of C/S structure with the rise of Internet technology. Under this architecture, the business logic of software application is completely realized on the application server, the user's performance is completely realized on the Web server, and the client only needs a browser for business processing, which is a brand-new software system construction technology. This architecture has become the first choice for today's applications. E-pass management series products belong to this structure.
In fact, for the problem 10, it is much more convenient to use NAT translation technology to translate private addresses into the network. For the above problems, this problem is solved by CIDR technology, and the calculation is relatively simple, that is, there are many calculation processes.
A: The marketing department has always been 16, and the engineering department started with 5, with one added every week and 54 added every year (it seems to be 54 weeks a year, I can't remember clearly) and then multiplied by 7,54 * 7+5 = 383.
As for the sales department, the address allocation is based on the future development, so the redundancy of the address space is determined according to the development degree, and the total address number n after 7 years is calculated, and the m power of 2 is -2=N, and m is the main seat, and the result comes out.
B: Maintenance time is simply calculated by function. If it is used up, there are two ways: 1, and then apply for NAT technology. 3. Because the B address is obtained, it will be redistributed with CIDR.
C: This question is the same as the beginning. There is no need to have an address, that is, a private address is used internally, and NAT technology is enough.