Ethereum grid

blockchain includes public blockchain, joint (instry) blockchain and private blockchain. Public chain point-to-point e-cash system: bitcoin, smart contract and decentralized application platform: Ethereum

blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies

blockchain is an important concept of bitcoin. In essence, it is a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of bitcoin network transaction information, Used to verify the validity of its information (anti-counterfeiting) and generate the next block

extended data

according to the different degree of blockchain network centralization, three kinds of blockchains under different application scenarios are differentiated:

1. The blockchain with the whole network open and without user authorization mechanism is called public chain

2. The authorized nodes are allowed to join the network, and the information can be viewed according to the authority. It is often used in the inter agency blockchain, which is called alliance chain or instry chain

3. All the nodes in the network are in the hands of one organization, which is called private chain

alliance chain and private chain are also called licensing chain, and public chain is called non licensing chain

blockchain features

1, decentralization. Blockchain technology does not rely on additional third-party management institutions or hardware facilities, and there is no central control. In addition to the self-contained blockchain itself, each node realizes information self verification, transmission and management through distributed accounting and storage. Decentralization is the most prominent and essential feature of blockchain

2. Openness. Blockchain technology is based on open source. In addition to the private information of all parties involved in the transaction is encrypted, the data of blockchain is open to everyone. Anyone can query blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent

3. Independence. Based on consensus specifications and Protocols (similar to various mathematical algorithms such as hash algorithm used by bitcoin), the whole blockchain system does not rely on other third parties, and all nodes can automatically and safely verify and exchange data in the system without any human intervention

4. Safety. As long as 51% of all data nodes cannot be controlled, the network data cannot be arbitrarily manipulated and modified, which makes the blockchain itself relatively safe and avoids subjective and artificial data changes

5. Anonymity. Unless there are legal requirements, technically speaking, the identity information of each block node does not need to be disclosed or verified, and the information can be transferred anonymously

The topological structure of LAN which is made up of Ethernet is mesh

when facing the construction of some large-scale networks, the mesh topology is generally used. Similarly, mesh topology is also a kind of combinatorial topology

it is composed of several subnets or LANs which are composed of the topology described above. Mesh topology is generally used in Internet backbone network, which uses routing algorithm to send the best path of data

extended data:

in computer network topology, network structure is the most complex network form, any node in the network will be connected with two or more lines, so as to keep connected with two or more nodes. Each node of network topology is connected with many lines, which has strong reliability and stability, and will be more suitable for WAN

because the way of sending information is broadcast, so the ability of sharing resources is strong. In order to solve the interference problem, we connect the terminator at both ends of the bus, mainly to match the impedance of the bus, absorb the energy of the transmission end as much as possible, and avoid unnecessary interference when the signal is reflected back to the bus

Gigabit Ethernet is a technology based on the basic Ethernet standard. Gigabit Ethernet and widely used Ethernet are fully compatible with fast Ethernet, and all technical specifications specified in the original Ethernet standard are used, including CSMA / CD protocol, Ethernet frame, full plex, flow control and management objects defined in IEEE802.3 standard. As a part of Ethernet, Gigabit Ethernet also supports traffic management technology, which guarantees the quality of service in Ethernet. These technologies include IEEE 802.1p layer 2 priority, layer 3 priority QoS coding bits, special service and resource reservation protocol (RSVP)

Gigabit Ethernet also uses IEEE 802.1qvlan support, layer 4 filtering, and Gigabit layer 3 switching. Gigabit Ethernet was originally designed as a switching technology, using optical fiber as the uplink for the connection between buildings. Since then, Gigabit Ethernet has been widely used in the connection of servers and backbone networks. Due to the introction of ieee802.3ab standard (Gigabit Ethernet standard using 5 types and above unshielded twisted pair), Gigabit Ethernet can be applied to any large, medium and small enterprises and institutions
Gigabit Ethernet has become the mainstream network technology. Large enterprises with tens of thousands of people, small and medium-sized enterprises with dozens of people will take Gigabit Ethernet technology as the preferred high-speed network technology when building enterprise LAN. Gigabit Ethernet technology is even replacing ATM technology and becoming the main force of man construction. 1. Gigabit Ethernet provides a perfect migration path to fully protect the investment in the existing network infrastructure. Gigabit Ethernet will retain IEEE802.3 and Ethernet frame formats as well as 802.3 managed object specifications, so that enterprises can upgrade to Gigabit performance while retaining existing cables, operating systems, protocols, desktop applications and network management strategies and tools< Compared with the original fast Ethernet, FDDI, ATM and other backbone network solutions, Gigabit Ethernet provides an optimal path. At least at present, it is a reliable and economical way to improve the backbone connection between switches and the connection between switches and servers. Network designers are able to build high-speed infrastructure for efficient use of high-speed, mission critical applications and file backup. Network administrators will provide users with faster access to Internet, intranet, man and WAN
3. IEEE 802.3 working group has established 802.3z and 802.3ab Gigabit Ethernet working groups, whose task is to develop Gigabit Ethernet standards to meet different requirements. The standard supports full plex and half plex 1000Mbps, and the corresponding operation adopts IEEE 802.3 Ethernet frame format and CSMA / CD medium access control method. Gigabit Ethernet is also backward compatible with 10baset and 100BaseT. In addition, IEEE standard will support multimode fiber with a maximum distance of 550 meters, single-mode fiber with a maximum distance of 70 kilometers and copper axis cable with a maximum distance of 100 meters. Gigabit Ethernet fills the gap of 802.3 Ethernet / Fast Ethernet standard. Gigabit Ethernet network is composed of Gigabit switch, Gigabit network card and generic cabling system. The Gigabit switch constitutes the backbone of the network. The Gigabit network card is installed on the server and connected with the switch through the wiring system. Many 100m switches can be connected under the Gigabit switch, and the 100m switch is connected to the workstation, which is the so-called "100m to desktop". In some professional graphics proction and video on demand applications, "Gigabit to desktop" may also be used, and a Gigabit switch is connected to a workstation with a gigabit network card, which meets the demand for high bandwidth in special applications
before the construction of the network, whether to use Gigabit or 100m, we should start from the reality, start from the application, and consider what functions the network should have. Different applications have different requirements, and almost no single service network. However, among all kinds of business, proctive business is definitely the highest priority. If the voice is transmitted in the network, the voice service also needs to be prioritized. If the demand for business priority is very high, the network must have QoS guarantee. Such a network must be intelligent, which can identify what type of service is passing through the switch port, then queue different services and allocate different bandwidth for different services, so as to ensure the operation of key services. Data service itself is intelligent, no matter how much bandwidth can be transmitted, just for a long time, but voice or video is different. If the bandwidth is small, you can't hear clearly immediately, or the image jitters, which is not allowed. So QoS is very important. For a simple data network, the demand for QoS is very low. When planning the network, we must first understand which functions are necessary and which can not be considered. For example, multiple access broadcasting is one of the most important performances. If we need to transmit images in the network, and the network does not have the characteristics of multiple access broadcasting, then the bandwidth waste of the network will be very serious, or even impossible to achieve. In January 1997, the first draft of ieee802.3z was approved
in June 1997, draft v3.1 was approved, and the final technical details were formulated
in June 1998, the ieee802.3z standard was officially approved
in June 1999, ieee802.3ab standard (1000BASE-T) was officially approved to use twisted pair in Gigabit Ethernet
the Gigabit Ethernet standard mainly aims at three types of transmission media: single-mode optical fiber; Long wave laser on multimode fiber (called 1000baselx) and short wave laser on multimode fiber (called 1000basesx); 1000basecx medium, which can be transmitted on 150 ohm copper cable with balanced shielding. The 1000baset standard simulated by ieee802.3z Committee allows the transmission distance of Gigabit Ethernet on Category 5, super category 5 and category 6 UTP twisted pair to be extended to 100 meters, so that most of the building wiring adopts category 5 UTP twisted pair, which ensures the user's previous investment in Ethernet and fast Ethernet. For network managers, there is no need to accept new training. With the Ethernet network knowledge, they can manage and maintain Gigabit Ethernet
the standardization of Gigabit Ethernet includes three main moles: coding / decoding, transceiver and network medium. Different transceivers correspond to different types of network medium. When 1000base-lx is based on 1300nm single-mode optical cable standard, 8B / 10B encoding and decoding mode is used, and the maximum transmission distance is 5000m. 1000base-sx is based on 780nm fibre channel optics, uses 8B / 10B encoding and decoding mode, uses 50 μ m or 62.5 μ m multimode optical cable, and the maximum transmission distance is 300 m to 500 m. The SC type optical fiber connector used for connecting optical fiber is the same as that used for fast Ethernet 100BaseFX. 1000base-cx is a standard based on copper cable, using 8B / 10B encoding and decoding mode, and the maximum transmission distance is 25m. 1000BASE-T is based on unshielded twisted pair transmission medium, using 1000BASE-T copper physical layer copper PHY encoding and decoding mode, and the transmission distance is 100 meters. 1000BASE-T uses all four pairs of twisted pair in transmission and works in full plex mode. This design uses pam-5 (5-stage pulse amplification molation) code to transmit 250 Mbps on each pair. Bidirectional transmission requires that all four wire pair transceiver ports must use hybrid magnetic field circuit, because it can not provide a perfect hybrid magnetic field circuit, so it can not completely isolate the sending and receiving circuits. Any sending and receiving line will echo the device. Therefore, in order to achieve the required BER, the echo must be cancelled. 1000BASE-T can't filter the frequency band concentrated above 125MHz, but it can filter the frequency band after 80MHz by using scrambling technology and trellis coding. In order to solve the limitation of class 5 line in such a high frequency range e to the near end crosstalk, we should adopt appropriate scheme to counteract the crosstalk
in the original Gigabit Ethernet, optical components of high-speed 780 nm optical fiber channel were used to transmit the signal on the optical fiber, and 8B / 10B encoding and decoding methods were used to realize the serialization and recovery of the optical signal. The data operation rate of optical fiber channel technology is 1.063gbps, which will be increased to 1.250gbps in the future, making the data rate reach the complete 1000Mbps. For longer connection distance, 1300 nm optical elements will be used. In order to adapt to the development of silicon technology and digital signal processing technology, a medium independent logic interface should be established between MAC layer and PHY layer to make Gigabit Ethernet work in unshielded twisted pair cable system. This logic interface will be suitable for the coding method of unshielded twisted pair cable system and independent of the coding method of optical fiber channel. The figure below illustrates the composition of Gigabit Ethernet. There are not many conditions for upgrading 10m and 100m networks to Gigabit, the most important of which is generic cabling. Gigabit Ethernet refers to the bandwidth of the network backbone, which requires that the backbone cabling system must meet the requirements of Gigabit Ethernet. If the original network covers several buildings with a distance of several hundred meters to several kilometers, the original backbone wiring generally uses multi-mode or single-mode optical fiber, which can meet the requirements of Gigabit backbone, so there is no need to re lay optical fiber. When the distance between buildings is less than 550 meters, the low-cost multimode optical fiber can meet the needs of Gigabit Ethernet
if the original network only covers one building, and the distance between the farthest network node and the network center is not more than 100 meters, the original category 5 or super category 5 cabling system can be used. If the original wiring system can not meet the category 5 standard, or if the bus type wiring system is adopted instead of the star type wiring system, the category 5 wiring must be re arranged
to upgrade to Gigabit Ethernet, the network backbone switch should be upgraded to Gigabit first, so as to improve the data flow that the network backbone can bear, so as to speed up the network speed. The former 100 MB switch was used as a branch switch, while the former hub could be used where the wiring points were insufficient. There are many procts of Gigabit switch, which can be selected according to the network requirements and budget
servers on the network need to handle a large amount of data. If the backbone of the network is upgraded to Gigabit, but the network card of the server is still at the level of 100m, the network card of the server will become the bottleneck of the network. We must use gigabit network card to eliminate this bottleneck. The solution is to add gigabit network card to the original server. Note that priority should be given to 64 bit PCI gigabit network card, its performance is higher than ordinary PCI gigabit network card. Gigabit network card can be selected according to the network requirements and budget
when the backbone of the network is upgraded, the branches of the network should also be upgraded. If the original user computer has installed 10m / 100M adaptive network card, it is not necessary to upgrade the network card, just connect the network card to the 100m switch; If the original 10Mbps network card is used, it is necessary to replace the network card with 10m / 100M adaptive network card, so as to improve the speed of workstation accessing the server. It is estimated that before 2005, the amount of data transmission will increase by three times every year, and exceed the amount of voice transmission in that year, becoming the main transmission mode of global communication network. In the face of the increasing data stream and multimedia services, big data stream is becoming more and more popular

1. Gigabit Ethernet provides a perfect migration path to fully protect the investment in the existing network infrastructure. Gigabit Ethernet will retain IEEE 802.3 and Ethernet frame formats as well as 802.3 managed object specifications
, enabling enterprises to upgrade to Gigabit performance while retaining existing cables, operating systems, protocols, desktop applications and network management strategies and tools< Compared with the original fast Ethernet, FDDI, ATM and other backbone network solutions, Gigabit Ethernet provides an optimal path. At least at present, it is a reliable and economical way to improve the backbone connection between switches and the connection between switches and servers. Network designers are able to build high-speed infrastructure for efficient use of high-speed, mission critical applications and file backup. Network administrators will provide users with faster access to Internet, intranet, man and WAN
3. IEEE 802.3 working group has established 802.3z and 802.3ab Gigabit Ethernet working groups, whose task is to develop Gigabit Ethernet standards to meet different requirements. The standard supports full plex and half plex 1000Mbps, and the corresponding operation adopts IEEE 802.3 Ethernet frame format and CSMA / CD medium access control method. Gigabit Ethernet is also backward compatible with 10baset and 100BaseT. In addition, IEEE standard will support multimode fiber with a maximum distance of 550 meters, single-mode fiber with a maximum distance of 70 kilometers and copper axis cable with a maximum distance of 100 meters. Gigabit Ethernet fills the gap of 802.3 Ethernet / Fast Ethernet standard. Gigabit Ethernet network is composed of Gigabit switch, Gigabit network card and generic cabling system. The Gigabit switch constitutes the backbone of the network. The Gigabit network card is installed on the server and connected with the switch through the wiring system. Many 100m switches can be connected under the Gigabit switch, and the 100m switch is connected to the workstation, which is the so-called "100m to desktop". In some professional graphics proction and video on demand applications, "Gigabit to desktop" may also be used, and a Gigabit switch is connected to a workstation with a gigabit network card, which meets the demand for high bandwidth in special applications
before the construction of the network, whether to use Gigabit or 100m, we should start from the reality, start from the application, and consider what functions the network should have. Different applications have different requirements, and almost no single service network. However, among all kinds of business, proctive business is definitely the highest priority. If the voice is transmitted in the network, the voice service also needs to be prioritized. If the demand for business priority is very high, the network must have QoS guarantee. Such a network must be intelligent, which can identify what type of service is passing through the switch port, then queue different services and allocate different bandwidth for different services, so as to ensure the operation of key services
the data service itself is intelligent. It can be transmitted no matter how much bandwidth, but only for a long time. However, voice or video is different. If the bandwidth is small, you can't hear clearly or the image jitters, which is not allowed. So QoS is very important. For a simple data network, the demand for QoS is very low. When planning the network, we must first understand which functions are necessary and which can not be considered. For example, at present, multiple access broadcasting is one of the most important performances. If we need to transmit images in the network, and the network does not have the characteristics of multiple access broadcasting, then the bandwidth waste of the network will be very serious, or even impossible to achieve. Gigabit Ethernet standard mainly aims at three types of transmission media: single-mode fiber; Long wave laser on multimode fiber (called 1000baselx) and short wave laser on multimode fiber (called 1000basesx); 1000basecx medium, which can be transmitted on 150 ohm copper cable with balanced shielding. The 1000baset standard simulated by IEEE 802.3z Committee allows the transmission distance of Gigabit Ethernet on Category 5, super category 5, and category 6 UTP twisted pair to be extended to 100 meters, so that most of the wiring in buildings adopts category 5 UTP twisted pair, which ensures users' previous investment in Ethernet and fast Ethernet. For network managers, there is no need to accept new training. With the Ethernet network knowledge, they can manage and maintain Gigabit Ethernet. The standardization of Gigabit Ethernet includes three main moles: coding / decoding, transceiver and network media. Different transceivers correspond to different types of network media. When 1000base-lx is based on 1300nm single-mode optical cable standard, 8B / 10B encoding and decoding mode is used, and the maximum transmission distance is 5000m
1000base-sx is based on 780nm fibre channel optics, uses 8B / 10B encoding and decoding mode, uses 50 μ m or 62.5 μ m multimode optical cable, and the maximum transmission distance is 300 m to 500 m. The SC type optical fiber connector used for connecting optical fiber is the same as that used for fast Ethernet 100BaseFX. 1000base-cx is a standard based on copper cable, using 8B / 10B encoding and decoding mode, and the maximum transmission distance is 25m
1000BASE-T is based on unshielded twisted pair transmission medium, using 1000BASE-T copper PHY encoding and decoding mode, and the transmission distance is 100 meters. 1000BASE-T uses all four pairs of twisted pair in transmission and works in full plex mode< This design uses pam-5 (5-stage pulse amplification molation) coding to transmit 250mbps on each
pair. Bidirectional transmission requires that all four wire pair transceiver ports must use hybrid magnetic field circuit, because it can not provide a perfect hybrid magnetic field circuit, so it can not completely isolate the sending and receiving circuits. Any sending and receiving line will echo the device. Therefore, in order to achieve the required BER, the echo must be cancelled. 1000BASE-T can't filter the frequency band concentrated above 125MHz, but it can filter the frequency band after 80MHz by using scrambling technology and trellis coding. In order to solve the limitation of class 5 line in such a high frequency range e to the near end crosstalk, we should adopt appropriate scheme to counteract the crosstalk. The original Gigabit Ethernet uses optical components of high-speed 780 nm optical fiber channel to transmit the signal on the optical fiber, and uses 8B / 10B encoding and decoding method to realize the serialization and recovery of the optical signal. At present, the data operation rate of optical fiber channel technology is 1.063gbps, which will be increased to 1.250gbps in the future, so that the data rate can reach the full 1000Mbps. For longer connection distance, 1300 nm optical elements will be used. In order to adapt to the development of silicon technology and digital signal processing technology, a medium independent logic interface should be established between MAC layer and PHY layer to make Gigabit Ethernet work in unshielded twisted pair cable system. This logic interface will be suitable for the coding method of unshielded twisted pair cable system and independent of the coding method of optical fiber channel. The formulation and implementation of Gigabit Ethernet standard provides a new choice for LAN upgrade. Gigabit Ethernet can be mainly used in the following situations: the connection between network server and network switch; Network switch to network switch connection; As the backbone of LAN, etc

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