Ethereum interface documentation
each version of Ethernet has a maximum cable length limit (that is, the length without amplification). Signals within this range can propagate normally, and signals beyond this range cannot propagate
in order to allow the construction of a larger network, repeaters can be used to connect multiple cables. Repeater is a physical layer device, which can receive, amplify and retransmit signals in two directions
extended data
several common Ethernet interface types
1. SC optical fiber interface
SC optical fiber interface has been applied in the era of 100base TX Ethernet, so it was called 100base FX at that time (F is the abbreviation of optical fiber). However, at that time, because the performance was not more prominent than twisted pair, but the cost was higher, so it was not popularized. Now the instry vigorously promotes gigabit network, and SC optical fiber interface is re valued
2. RJ-45 interface
this kind of interface is the most common network equipment interface, commonly known as "crystal head", and the professional term is RJ-45 connector, which belongs to the type of twisted pair Ethernet interface. RJ-45 plug can only be inserted along the fixed direction, and a plastic spring piece is set to be stuck with RJ-45 slot to prevent it from falling off
3. FDDI interface
FDDI has the highest transmission rate among the mature LAN technologies. It has the characteristics of timed token protocol, supports a variety of topologies, and its transmission medium is optical fiber. Fiber distributed data interface (FDDI) is a set of protocols developed by American National Organization for Standardization (ANSI) to transmit digital signals on optical cables
reference source: Network Ethernet interface
If you want to query the transaction records on the main network, you can use Etherscan. However, if you build your own private chain, how should you query the transaction records
the answer is that you need to listen to the logs on the chain, save them in the database, and then query them in the database. For example:
< pre t = "code" L = "Java" > varaddr = & quot& quot;< br />varfilter=web3.eth.filter({fromB lock:0 ,toBlock:' latest', address:addr });< br />filter.get(function(err,transactions){transactions.forEach(function(tx){
vartxInfo=web3.eth.getTransaction(tx.transactionHash);
/ / at this time, the transaction information txinfo can be stored in the database
})< br />});
Web3. Eth. Filter() is used to monitor the log on the chain, and Web3. Eth. Gettransaction() is used to extract the information of the specified transaction. Once the transaction information is obtained, it can be stored in the database for query
recommend a practical introction, you can see: Ethereum tutorial
however, when I first used it, I encountered a problem, that is, the router simulated by IOS XR only has two physical interfaces: mgmteth0 / 0 / cpu0 / 0, and gigabitethernet 0 / 0 / 0 / 0, which is obviously not enough to play
therefore, under VMware, add the [network adapter] of the virtual machine. No matter how much you add it, the number of physical interfaces in the IOS XR system is always the same. What can you do
the solution is as follows: IOS XR virtual machine in my document, under the corresponding folder, there is a file: xxxxx.vmx, which corresponds to the name of the virtual machine. Use WordPad to open (Note: do not use Notepad to open and edit, because this will cause an error to be reported when running the virtual machine at last, and prompt "dictionary error"). In this document, there are some information about IOS XR physical interface, such as:
Ethernet0. Present = & quot; TRUE"< br />ethernet0.virtualDev = " e1000"< br />ethernet0.connectionType = " bridged"< br />ethernet0.startConnected = " TRUE"< br />ethernet0.addressType = " generated"< br />ethernet0.generatedAddress = " 00:0c:29:1c:1d:34"
in this document, the number of Ethernet is consistent with the number of network adapters in the virtual machine. According to the MAC address of each Ethernet in the document, it can correspond to each network adapter in the virtual machine. Therefore, as long as the [network adapter] of the virtual machine is added, the number of Ethernet in this document will be increased, and the corresponding configuration will be added
however, the problem to be solved in this paper is rooted in a command: Ethernet0. Virtualdev = & quot; e1000"， By default, this command is available for Ethernet 0 and Ethernet 1, but not for other physical interfaces such as Ethernet 2 and Ethernet 3. Therefore, the router virtualized by IOS XR has no corresponding physical interface. By adding the following commands, we can solve the problem of unable to add physical interface of Router:
Ethernet 2. Virtualdev = & quot; e1000"< br />ethernet3.virtualDev = " e1000"
you can add [network adapter] in the virtual machine according to your own test needs, and add the above command in the VMX file, save the document, open it again, and you can see that the physical interface of the IOS XR router has increased, As follows
RP / 0 / 0 / cpu0: XR? Sho IP int bri
Thu Jul 16 22:45:55.638 UTC
interface IP address status protocol
mgmteth0 / 0 / cpu0 / 0 unassigned shutdown down
gigabitethernet 0 / 0 / 0 unassigned up
gigabitethernet ET0 / 0 / 0 / 1 unassigned shutdown down
gigabitethernet 0 / 0 / 0 / 2 unassigned shutdown down
gigabitethernet 0 / 0 / 0 / 3 unassigned shutdown down
note that when modifying the VMX document, you need to close the virtual machine first, save the closed document, and then open the virtual machine
when IOS XR virtual machine is just started, it is relatively slow, and it takes a long time to load the configuration, and the previous configuration can not be saved. As long as you wait for a period of time, you can resume normal use.
java_ The home value is: the directory where JDK is installed, and mine is C: &# 92; Program Files\ Java\ jdk1.6.0_ 34
the classpath value is:;% JAVA_ HOME%\ lib\ tools.jar;% JAVA_ HOME%\ lib\ dt.jar;% JAVA_ HOME%\ bin;( Pay attention to the & quot& quot; To add)
Path: append at the beginning.;% JAVA_ HOME%\ bin;% JAVA_ HOME%\ jre\ bin;( Pay attention to the & quot& quot; To add)
after the installation, you can check whether the JDK is installed successfully. Open the CMD window and enter Java – version to view the version information of JDK.
Take a blockchain API tool that I am currently using as an example
previously, I occasionally found bctools , which can quickly and conveniently test and verify BTC and EOS blockchain API. At the same time, these API interface test network and main network can be verified on bctools ; If you are interested, you can go http://bctools.io Use it
at present, Apis on bctools seem to have the following types:
After reading the answers of other respondents, I really want to laugh. It's not terrible to pretend that I don't understand. What's terrible is to answer blindly. There's something wrong with this question. The burst of 5.7 billion yuan has nothing to do with a drop of 10 cents. It can even be said that its disappearance is e to the sharp rise. So where is the decline? If bitcoin really falls, it will not be 5.7 billion capital washed away, it will be tens of billions, hundreds of billions of capital evaporated, those who talk about trends and development, please study the capital and stock market well, and by the way, please search for the meaning of the word "burst", no culture is too terrible
in addition, I would like to make a digression. Recently, a hot topic is fund. In 2021, the annual meeting is more or less a national fund. In 2020, the fund manager is still a good active fund. Even if the position is not changed, the annual yield will reach at least 40%, but this does not mean that this year is still OK, It's not that everyone can make money playing with funds. it's similar to the nature of stocks. Index funds, stock funds and even active funds are risky. I think many people say that they should get on the bus quickly. They are really worried about your funds of course, 2021 may be a bull market. It is estimated that the whole network has spread, many people are rubbing their hands to make a lot of money, but I can't do much. I just advise you not to go with the flow too much, don't be greedy, and don't think you are. That's all. Good luck