The relationship between Ethereum and Ethernet
Publish: 2021-05-19 23:25:27
1. The Ge port is a Gigabit Ethernet port, and the ETH port is a fast Ethernet port, that is, a 100M Ethernet port.
2. Ethernet was first proposed by Xerox company in the 1970s as a baseband LAN standard. The transmission rate is 10mbit / s. The medium is coaxial cable and CSMA / CD is used as MAC layer control protocol.
Internet Internet is the largest information network in the world, Users can achieve global e-mail.www.information query, e-mail file transmission, network entertainment, voice and image communication services and other functions, At the beginning, there were only four hosts, which were located in the US Department of defense, the Atomic Energy Commission, the California Institute of technology and the Massachusetts Institute of technology. After decades of development, they have reached today's scale.
the concept of the Internet has expanded, and LAN can be the Internet.
it should be said that the network composed of two or more computers is called the Internet
Internet Internet is the largest information network in the world, Users can achieve global e-mail.www.information query, e-mail file transmission, network entertainment, voice and image communication services and other functions, At the beginning, there were only four hosts, which were located in the US Department of defense, the Atomic Energy Commission, the California Institute of technology and the Massachusetts Institute of technology. After decades of development, they have reached today's scale.
the concept of the Internet has expanded, and LAN can be the Internet.
it should be said that the network composed of two or more computers is called the Internet
3. Your problem is a matter of concept. Professional people don't talk about it much, but they can see it for themselves http://ke..com/view/848.html?wtp=tt
http://ke..com/view/54303.htm
generally speaking, Ethernet is the traffic road, and CSMA / CD is the traffic police working on Ethernet
CSMA / CD works in the fourth pair of twisted pair, and each pair works in half plex mode
http://ke..com/view/54303.htm
generally speaking, Ethernet is the traffic road, and CSMA / CD is the traffic police working on Ethernet
CSMA / CD works in the fourth pair of twisted pair, and each pair works in half plex mode
4. LAN -- local area network: LAN
Wan -- wide area network: Wan
Ethernet -- the original English name is Ethernet, which is transliterated. It is a kind of LAN, but other LAN types, such as token ring and FDDI, are no longer used
so it can be generally considered that: Ethernet ≈ LAN (local area network)
LAN is generally used for the internal network of an organization
now the Internet belongs to Wan, global access!
Wan -- wide area network: Wan
Ethernet -- the original English name is Ethernet, which is transliterated. It is a kind of LAN, but other LAN types, such as token ring and FDDI, are no longer used
so it can be generally considered that: Ethernet ≈ LAN (local area network)
LAN is generally used for the internal network of an organization
now the Internet belongs to Wan, global access!
5. It doesn't matter.
6. LAN is a network divided by coverage area, while Ethernet is a layer-2 protocol
for example, according to the coverage area, it can be divided into LAN, man and WAN
while according to the layer-2 protocol, it can be divided into Ethernet, ATM network and so on.
for example, according to the coverage area, it can be divided into LAN, man and WAN
while according to the layer-2 protocol, it can be divided into Ethernet, ATM network and so on.
7. Gigabit Ethernet: the transmission rate of Gigabit Ethernet is 10 times faster than that of Fast Ethernet, and the data transmission rate reaches 1000Mbps. Gigabit Ethernet retains all the characteristics of traditional 10Mbps Ethernet (the same data frame format, the same media access control method, and the same networking method), It only reces the transmission time of each bit of traditional Ethernet from 100ns to 1ns; Convenient communication service (e-mail); Fast e-commerce (China's earliest business platform 8488)
Internet backbone: ansnet.
from the perspective of network designers, the Internet is a computer Internet.
from the perspective of users, The Internet is an information resource network.
there are two main types of communication lines in the Internet: wired lines and wireless lines.
the Internet is mainly composed of communication lines, routers, servers and clients, Information resources are composed of four parts.
all computers connected to the Internet are collectively referred to as hosts.
servers are providers of Internet services and information resources. Clients are users of Internet services and information resources.
TCP / IP protocol is the link that binds them together. TCP / IP is a set of protocols that address hosts in the Internet, The naming mechanism, information transmission rules and various service functions of the host are specified in detail.
IP (communication rules) is mainly responsible for addressing datagrams transmitted between computers, The network layer running IP protocol can provide the following three services for its high-level users:
1. Unreliable data delivery service 3. Service.
4. Connectionless transport service 5. Service.
6. Best effort delivery service 7. Service.
IP address consists of two parts, 1. Network number and 2. Host number. As long as two hosts have the same network number, regardless of their physical location, they belong to the same logical network.
class a IP address is used for large-scale network. Class B IP address is used for medium-sized network. Class C IP address is used for small-scale network, Only 256 devices can be connected at most. Class D IP is used for multi-purpose address transmission. Class E IP is reserved for future use.
the network number and host number of IP address are divided again by subnet mask code.
the format of IP datagram can be divided into header area and data area, in which the data area includes the data to be transmitted by high layer, The header area is the additional control information for the correct transmission of high-level data.
in the Internet, The devices that need routing usually adopt table driven routing algorithm.
there are two basic forms of routing table: 1. Static routing table. 2. Dynamic routing table. Dynamic routing table is established by routers in the network automatically sending routing information to each other.
TCP provides reliable data transmission service for the application layer. TCP is an end-to-end transmission protocol, Because it can provide a direct connection from one application of a host to another application of a remote host. (virtual connection)
port is designed by TCP and UDP in order to identify multiple targets on a host.
the domain name of Internet is defined by the domain name system in TCP / IP protocol set.
this naming structure in Internet only represents one The logical organization method does not represent the actual physical connection. With the help of a group of independent and cooperative domain name servers, there are a large number of domain name servers on the Internet. Each domain name server keeps a comparison table of the host's name and IP address in the domain, This group of name servers is the core of the resolution system.
there are two ways of domain name resolution: 1. Recursive resolution. 2. Repeated resolution.
the basic services provided by the Internet are:
1. E-mail.
2. Remote login telnet
3. File transmission FTP.
4. WWW service. 5. Service.
e-mail service adopts client / server mode.
users send and receive E-mail needs to be completed with the help of e-mail application installed in the client.
e-mail application should have the following two basic functions:
1. Create and send e-mail.
2. Receive, read, Manage e-mail.
when e-mail application transmits e-mail to e-mail server, it uses simple mail transfer protocol (SMTP). When reading from e-mail server, it can use POP3 protocol or IMAP protocol.
when e-mail application accesses IMAP server, users can decide whether to e-mail to client or keep a of e-mail in IMAP server, Users can read and manage e-mail directly in the server.
e-mail consists of two parts: the e-mail header and the e-mail body (the content actually transmitted).
remote terminal protocol, namely telnet protocol, which is a part of TCP / IP protocol, It precisely defines the interaction process between the local client and the remote server.
the remote login service provided by the Internet can be realized:
1. The local user interacts with the program running on the remote computer.
2. When the user logs on to the remote computer, he can execute any application program on the remote computer, And can shield the difference between different types of computers.
4. Users can use personal computers to complete many tasks that only mainframe can complete.
Network Virtual Terminal: provides a standard keyboard definition, It is used to shield the difference of keyboard input between different computer systems.
there are three types of FTP client applications used by Internet users, namely traditional FTP command line, browser and FTP download tool.
this feature of connecting with other texts in text forms the biggest feature of hypertext: disorder.
the process of selecting hot words, HTTP is the application layer transport protocol between www client and WWW server.
HTTP session process includes the following four steps:
1. Connection. 2. Request. 3. Response. 4. Close.
URL consists of three parts: protocol type, host name and path, and file name< The page stored in WWW server is a kind of structured document, which is written by HTML.
the main feature of HTML is that it can contain links to other documents, that is, URLs of other pages.
another feature is that it can gather multimedia information such as sound, image and video together
for institutions, the home page is usually the default page of the WWW server. When users enter a URL, they only need to give the host name of the WWW server without specifying a specific path and file name. The WWW server will automatically return its default page to the users.
Search engine is a WWW server on the Internet, Its main task is to search the information of other WWW servers in the Internet actively and index them automatically, and store the index content in a large database that can be queried.
Internet newsgroup is an international forum that uses the Internet for special topic discussion. Up to now, Usenet is still the largest Internet newsgroup.
ISP provides Internet access service for users, On the other hand, it provides users with various types of information services.
users' computers can be connected to ISPs through various communication lines, but they can be divided into two categories: telephone lines and data communication lines.
the modem is responsible for converting the digital information output by the computer into signals that can be transmitted by ordinary telephone lines, At the other end, the signal received from the telephone line is converted into the digital signal that can be processed by the computer.
the cost of intervening in the Internet through the telephone line usually consists of three parts: account opening fee, Internet usage fee (connection fee and cost of occupying disk space) and telephone fee.
Internet backbone: ansnet.
from the perspective of network designers, the Internet is a computer Internet.
from the perspective of users, The Internet is an information resource network.
there are two main types of communication lines in the Internet: wired lines and wireless lines.
the Internet is mainly composed of communication lines, routers, servers and clients, Information resources are composed of four parts.
all computers connected to the Internet are collectively referred to as hosts.
servers are providers of Internet services and information resources. Clients are users of Internet services and information resources.
TCP / IP protocol is the link that binds them together. TCP / IP is a set of protocols that address hosts in the Internet, The naming mechanism, information transmission rules and various service functions of the host are specified in detail.
IP (communication rules) is mainly responsible for addressing datagrams transmitted between computers, The network layer running IP protocol can provide the following three services for its high-level users:
1. Unreliable data delivery service 3. Service.
4. Connectionless transport service 5. Service.
6. Best effort delivery service 7. Service.
IP address consists of two parts, 1. Network number and 2. Host number. As long as two hosts have the same network number, regardless of their physical location, they belong to the same logical network.
class a IP address is used for large-scale network. Class B IP address is used for medium-sized network. Class C IP address is used for small-scale network, Only 256 devices can be connected at most. Class D IP is used for multi-purpose address transmission. Class E IP is reserved for future use.
the network number and host number of IP address are divided again by subnet mask code.
the format of IP datagram can be divided into header area and data area, in which the data area includes the data to be transmitted by high layer, The header area is the additional control information for the correct transmission of high-level data.
in the Internet, The devices that need routing usually adopt table driven routing algorithm.
there are two basic forms of routing table: 1. Static routing table. 2. Dynamic routing table. Dynamic routing table is established by routers in the network automatically sending routing information to each other.
TCP provides reliable data transmission service for the application layer. TCP is an end-to-end transmission protocol, Because it can provide a direct connection from one application of a host to another application of a remote host. (virtual connection)
port is designed by TCP and UDP in order to identify multiple targets on a host.
the domain name of Internet is defined by the domain name system in TCP / IP protocol set.
this naming structure in Internet only represents one The logical organization method does not represent the actual physical connection. With the help of a group of independent and cooperative domain name servers, there are a large number of domain name servers on the Internet. Each domain name server keeps a comparison table of the host's name and IP address in the domain, This group of name servers is the core of the resolution system.
there are two ways of domain name resolution: 1. Recursive resolution. 2. Repeated resolution.
the basic services provided by the Internet are:
1. E-mail.
2. Remote login telnet
3. File transmission FTP.
4. WWW service. 5. Service.
e-mail service adopts client / server mode.
users send and receive E-mail needs to be completed with the help of e-mail application installed in the client.
e-mail application should have the following two basic functions:
1. Create and send e-mail.
2. Receive, read, Manage e-mail.
when e-mail application transmits e-mail to e-mail server, it uses simple mail transfer protocol (SMTP). When reading from e-mail server, it can use POP3 protocol or IMAP protocol.
when e-mail application accesses IMAP server, users can decide whether to e-mail to client or keep a of e-mail in IMAP server, Users can read and manage e-mail directly in the server.
e-mail consists of two parts: the e-mail header and the e-mail body (the content actually transmitted).
remote terminal protocol, namely telnet protocol, which is a part of TCP / IP protocol, It precisely defines the interaction process between the local client and the remote server.
the remote login service provided by the Internet can be realized:
1. The local user interacts with the program running on the remote computer.
2. When the user logs on to the remote computer, he can execute any application program on the remote computer, And can shield the difference between different types of computers.
4. Users can use personal computers to complete many tasks that only mainframe can complete.
Network Virtual Terminal: provides a standard keyboard definition, It is used to shield the difference of keyboard input between different computer systems.
there are three types of FTP client applications used by Internet users, namely traditional FTP command line, browser and FTP download tool.
this feature of connecting with other texts in text forms the biggest feature of hypertext: disorder.
the process of selecting hot words, HTTP is the application layer transport protocol between www client and WWW server.
HTTP session process includes the following four steps:
1. Connection. 2. Request. 3. Response. 4. Close.
URL consists of three parts: protocol type, host name and path, and file name< The page stored in WWW server is a kind of structured document, which is written by HTML.
the main feature of HTML is that it can contain links to other documents, that is, URLs of other pages.
another feature is that it can gather multimedia information such as sound, image and video together
for institutions, the home page is usually the default page of the WWW server. When users enter a URL, they only need to give the host name of the WWW server without specifying a specific path and file name. The WWW server will automatically return its default page to the users.
Search engine is a WWW server on the Internet, Its main task is to search the information of other WWW servers in the Internet actively and index them automatically, and store the index content in a large database that can be queried.
Internet newsgroup is an international forum that uses the Internet for special topic discussion. Up to now, Usenet is still the largest Internet newsgroup.
ISP provides Internet access service for users, On the other hand, it provides users with various types of information services.
users' computers can be connected to ISPs through various communication lines, but they can be divided into two categories: telephone lines and data communication lines.
the modem is responsible for converting the digital information output by the computer into signals that can be transmitted by ordinary telephone lines, At the other end, the signal received from the telephone line is converted into the digital signal that can be processed by the computer.
the cost of intervening in the Internet through the telephone line usually consists of three parts: account opening fee, Internet usage fee (connection fee and cost of occupying disk space) and telephone fee.
8. Ethernet uses CSMA / CD technology, the standard is 802.3, is a software and hardware standard
the concept of direct network is based on routing. For example, two computers are directly connected by network cable, which is called direct network. Non direct network usually forwards data through "hop"
take a look at your question below. WiFi is different from 802.11. Although Wi-Fi uses 802.11's MAC and PHY, they are not exactly the same. I don't know how different they are. General wireless router network is 802.11 wireless standard, not Ethernet.
the concept of direct network is based on routing. For example, two computers are directly connected by network cable, which is called direct network. Non direct network usually forwards data through "hop"
take a look at your question below. WiFi is different from 802.11. Although Wi-Fi uses 802.11's MAC and PHY, they are not exactly the same. I don't know how different they are. General wireless router network is 802.11 wireless standard, not Ethernet.
9. Gigabit Ethernet: the transmission rate of Gigabit Ethernet is 10 times faster than that of Fast Ethernet, and the data transmission rate reaches 1000Mbps. Gigabit Ethernet retains all the characteristics of traditional 10Mbps Ethernet (the same data frame format, the same media access control method, and the same networking method), It only reces the transmission time of each bit of traditional Ethernet from 100ns to 1ns; Convenient communication service (e-mail); Fast e-commerce (China's earliest business platform 8488)
Internet backbone: ansnet.
from the perspective of network designers, the Internet is a computer Internet.
from the perspective of users, The Internet is an information resource network.
there are two main types of communication lines in the Internet: wired lines and wireless lines.
the Internet is mainly composed of communication lines, routers, servers and clients, Information resources are composed of four parts.
all computers connected to the Internet are collectively referred to as hosts.
servers are providers of Internet services and information resources. Clients are users of Internet services and information resources.
TCP / IP protocol is the link that binds them together. TCP / IP is a set of protocols that address hosts in the Internet, The naming mechanism, information transmission rules and various service functions of the host are specified in detail.
IP (communication rules) is mainly responsible for addressing datagrams transmitted between computers, The network layer running IP protocol can provide the following three services for its high-level users:
1. Unreliable data delivery service 3. Service.
4. Connectionless transport service 5. Service.
6. Best effort delivery service 7. Service.
IP address consists of two parts, 1. Network number and 2. Host number. As long as two hosts have the same network number, regardless of their physical location, they belong to the same logical network.
class a IP address is used for large-scale network. Class B IP address is used for medium-sized network. Class C IP address is used for small-scale network, Only 256 devices can be connected at most. Class D IP is used for multi-purpose address transmission. Class E IP is reserved for future use.
the network number and host number of IP address are divided again by subnet mask code.
the format of IP datagram can be divided into header area and data area, in which the data area includes the data to be transmitted by high layer, The header area is the additional control information for the correct transmission of high-level data.
in the Internet, The devices that need routing usually adopt table driven routing algorithm.
there are two basic forms of routing table: 1. Static routing table. 2. Dynamic routing table. Dynamic routing table is established by routers in the network automatically sending routing information to each other.
TCP provides reliable data transmission service for the application layer. TCP is an end-to-end transmission protocol, Because it can provide a direct connection from one application of a host to another application of a remote host. (virtual connection)
port is designed by TCP and UDP in order to identify multiple targets on a host.
the domain name of Internet is defined by the domain name system in TCP / IP protocol set.
this naming structure in Internet only represents one The logical organization method does not represent the actual physical connection. With the help of a group of independent and cooperative domain name servers, there are a large number of domain name servers on the Internet. Each domain name server keeps a comparison table of the host's name and IP address in the domain, This group of name servers is the core of the resolution system.
there are two ways of domain name resolution: 1. Recursive resolution. 2. Repeated resolution.
the basic services provided by the Internet are:
1. E-mail.
2. Remote login telnet
3. File transmission FTP.
4. WWW service. 5. Service.
e-mail service adopts client / server mode.
users send and receive E-mail needs to be completed with the help of e-mail application installed in the client.
e-mail application should have the following two basic functions:
1. Create and send e-mail.
2. Receive, read, Manage e-mail.
when e-mail application transmits e-mail to e-mail server, it uses simple mail transfer protocol (SMTP). When reading from e-mail server, it can use POP3 protocol or IMAP protocol.
when e-mail application accesses IMAP server, users can decide whether to e-mail to client or keep a of e-mail in IMAP server, Users can read and manage e-mail directly in the server.
e-mail consists of two parts: the e-mail header and the e-mail body (the content actually transmitted).
remote terminal protocol, namely telnet protocol, which is a part of TCP / IP protocol, It precisely defines the interaction process between the local client and the remote server.
the remote login service provided by the Internet can be realized:
1. The local user interacts with the program running on the remote computer.
2. When the user logs on to the remote computer, he can execute any application program on the remote computer, And can shield the difference between different types of computers.
4. Users can use personal computers to complete many tasks that only mainframe can complete.
Network Virtual Terminal: provides a standard keyboard definition, It is used to shield the difference of keyboard input between different computer systems.
there are three types of FTP client applications used by Internet users, namely traditional FTP command line, browser and FTP download tool.
this feature of connecting with other texts in text forms the biggest feature of hypertext: disorder.
the process of selecting hot words, HTTP is the application layer transport protocol between www client and WWW server.
HTTP session process includes the following four steps:
1. Connection. 2. Request. 3. Response. 4. Close.
URL consists of three parts: protocol type, host name and path, and file name< The page stored in WWW server is a kind of structured document, which is written by HTML.
the main feature of HTML is that it can contain links to other documents, that is, URLs of other pages.
another feature is that it can gather multimedia information such as sound, image and video together
for institutions, the home page is usually the default page of the WWW server. When users enter a URL, they only need to give the host name of the WWW server without specifying a specific path and file name. The WWW server will automatically return its default page to the users.
Search engine is a WWW server on the Internet, Its main task is to search the information of other WWW servers in the Internet actively and index them automatically, and store the index content in a large database that can be queried.
Internet newsgroup is an international forum that uses the Internet for special topic discussion. Up to now, Usenet is still the largest Internet newsgroup.
ISP provides Internet access service for users, On the other hand, it provides users with various types of information services.
users' computers can be connected to ISPs through various communication lines, but they can be divided into two categories: telephone lines and data communication lines.
the modem is responsible for converting the digital information output by the computer into signals that can be transmitted by ordinary telephone lines, At the other end, the signal received from the telephone line is converted into digital signal that can be processed by the computer.
the cost of Internet access through telephone line usually consists of three parts: account opening fee, Internet usage fee (connection fee and disk space cost) and telephone fee
Internet backbone: ansnet.
from the perspective of network designers, the Internet is a computer Internet.
from the perspective of users, The Internet is an information resource network.
there are two main types of communication lines in the Internet: wired lines and wireless lines.
the Internet is mainly composed of communication lines, routers, servers and clients, Information resources are composed of four parts.
all computers connected to the Internet are collectively referred to as hosts.
servers are providers of Internet services and information resources. Clients are users of Internet services and information resources.
TCP / IP protocol is the link that binds them together. TCP / IP is a set of protocols that address hosts in the Internet, The naming mechanism, information transmission rules and various service functions of the host are specified in detail.
IP (communication rules) is mainly responsible for addressing datagrams transmitted between computers, The network layer running IP protocol can provide the following three services for its high-level users:
1. Unreliable data delivery service 3. Service.
4. Connectionless transport service 5. Service.
6. Best effort delivery service 7. Service.
IP address consists of two parts, 1. Network number and 2. Host number. As long as two hosts have the same network number, regardless of their physical location, they belong to the same logical network.
class a IP address is used for large-scale network. Class B IP address is used for medium-sized network. Class C IP address is used for small-scale network, Only 256 devices can be connected at most. Class D IP is used for multi-purpose address transmission. Class E IP is reserved for future use.
the network number and host number of IP address are divided again by subnet mask code.
the format of IP datagram can be divided into header area and data area, in which the data area includes the data to be transmitted by high layer, The header area is the additional control information for the correct transmission of high-level data.
in the Internet, The devices that need routing usually adopt table driven routing algorithm.
there are two basic forms of routing table: 1. Static routing table. 2. Dynamic routing table. Dynamic routing table is established by routers in the network automatically sending routing information to each other.
TCP provides reliable data transmission service for the application layer. TCP is an end-to-end transmission protocol, Because it can provide a direct connection from one application of a host to another application of a remote host. (virtual connection)
port is designed by TCP and UDP in order to identify multiple targets on a host.
the domain name of Internet is defined by the domain name system in TCP / IP protocol set.
this naming structure in Internet only represents one The logical organization method does not represent the actual physical connection. With the help of a group of independent and cooperative domain name servers, there are a large number of domain name servers on the Internet. Each domain name server keeps a comparison table of the host's name and IP address in the domain, This group of name servers is the core of the resolution system.
there are two ways of domain name resolution: 1. Recursive resolution. 2. Repeated resolution.
the basic services provided by the Internet are:
1. E-mail.
2. Remote login telnet
3. File transmission FTP.
4. WWW service. 5. Service.
e-mail service adopts client / server mode.
users send and receive E-mail needs to be completed with the help of e-mail application installed in the client.
e-mail application should have the following two basic functions:
1. Create and send e-mail.
2. Receive, read, Manage e-mail.
when e-mail application transmits e-mail to e-mail server, it uses simple mail transfer protocol (SMTP). When reading from e-mail server, it can use POP3 protocol or IMAP protocol.
when e-mail application accesses IMAP server, users can decide whether to e-mail to client or keep a of e-mail in IMAP server, Users can read and manage e-mail directly in the server.
e-mail consists of two parts: the e-mail header and the e-mail body (the content actually transmitted).
remote terminal protocol, namely telnet protocol, which is a part of TCP / IP protocol, It precisely defines the interaction process between the local client and the remote server.
the remote login service provided by the Internet can be realized:
1. The local user interacts with the program running on the remote computer.
2. When the user logs on to the remote computer, he can execute any application program on the remote computer, And can shield the difference between different types of computers.
4. Users can use personal computers to complete many tasks that only mainframe can complete.
Network Virtual Terminal: provides a standard keyboard definition, It is used to shield the difference of keyboard input between different computer systems.
there are three types of FTP client applications used by Internet users, namely traditional FTP command line, browser and FTP download tool.
this feature of connecting with other texts in text forms the biggest feature of hypertext: disorder.
the process of selecting hot words, HTTP is the application layer transport protocol between www client and WWW server.
HTTP session process includes the following four steps:
1. Connection. 2. Request. 3. Response. 4. Close.
URL consists of three parts: protocol type, host name and path, and file name< The page stored in WWW server is a kind of structured document, which is written by HTML.
the main feature of HTML is that it can contain links to other documents, that is, URLs of other pages.
another feature is that it can gather multimedia information such as sound, image and video together
for institutions, the home page is usually the default page of the WWW server. When users enter a URL, they only need to give the host name of the WWW server without specifying a specific path and file name. The WWW server will automatically return its default page to the users.
Search engine is a WWW server on the Internet, Its main task is to search the information of other WWW servers in the Internet actively and index them automatically, and store the index content in a large database that can be queried.
Internet newsgroup is an international forum that uses the Internet for special topic discussion. Up to now, Usenet is still the largest Internet newsgroup.
ISP provides Internet access service for users, On the other hand, it provides users with various types of information services.
users' computers can be connected to ISPs through various communication lines, but they can be divided into two categories: telephone lines and data communication lines.
the modem is responsible for converting the digital information output by the computer into signals that can be transmitted by ordinary telephone lines, At the other end, the signal received from the telephone line is converted into digital signal that can be processed by the computer.
the cost of Internet access through telephone line usually consists of three parts: account opening fee, Internet usage fee (connection fee and disk space cost) and telephone fee
10. Data link layer and Ethernet:
1.
functions of data link layer:
data link layer is divided into logical link control sublayer and media access control sublayer; LLC sublayer is implemented in software and MAC sublayer is implemented in hardware; The function of LLC sub layer is mainly used to determine the network layer protocol used by the frame. This information allows multiple layer 3 protocols (such as IPv4, IPv6 and IPX) to use the same network interface and media; The function of MAC sublayer mainly provides data link layer addressing and data decomposition methods according to the physical signal requirements of media and the type of data link layer protocol used. That is to say, the source MAC address and target MAC address are determined according to the requirements of media type, and the frame head and frame tail and FCS (error detection) are added<
2.
topology: in different network topologies, do we access media in a controlled or contention way. In the early Ethernet multi-channel access, we used contention mechanism. Contention, as the name suggests, is to scramble; Controlled is the mechanism of token ring, which is mainly based on the way of rotation<
3.
the working process of CSMA / CD:
4.
the working principle of ARP:
5.
the working principle of switch:
6.
conflict domain and broadcast domain: CSMA / CD is the abbreviation of carrier sense multiple access / collision detected, It can be translated into "carrier reconnaissance listening multiple access / collision detection" or "carrier listening multiple access with collision detection". Carrier sense means that each workstation on the network must have data transmission on the bus before sending data. If the bus is busy, the data will not be sent; If there is no data transmission (the bus is called empty), send the prepared data immediately. The so-called multiple access means that all workstations on the network use the same bus to send and receive data, and the data is broadcast. The so-called collision means that if there are two or more workstations on the network sending data at the same time, the signal will be mixed on the bus. If any workstation sends data at the same time, the signal will be generated on the bus. Mixed, no workstation can tell what the real data is. This situation is called data conflict or collision. In order to rece the impact of the conflict. In the process of sending data, the workstation should constantly detect whether the data it sends conflicts with the data of other workstations in the process of transmission, which is called collision detected. The working principle of CSNM / CD media access control method can be summarized as follows: listening before speaking, listening while speaking; In case of conflict, stop talking immediately; Wait for the moment, and then talk about it; Listening means monitoring and testing; It means to send data. Before sending data, monitor whether the bus is idle. If the bus is busy, it will not be sent. If the bus is idle, the prepared data is sent to the bus. In the process of sending data, the workstation sends the detection bus to check whether the data sent by itself conflicts. If there is no conflict, continue to send until all data is sent; If there is a conflict, stop sending data immediately, but send a jam signal to strengthen the conflict, so that all work sites on the network know that there is a conflict on the network. Then, wait for a predetermined random time, and when the bus is idle, resend the unfinished data.
1.
functions of data link layer:
data link layer is divided into logical link control sublayer and media access control sublayer; LLC sublayer is implemented in software and MAC sublayer is implemented in hardware; The function of LLC sub layer is mainly used to determine the network layer protocol used by the frame. This information allows multiple layer 3 protocols (such as IPv4, IPv6 and IPX) to use the same network interface and media; The function of MAC sublayer mainly provides data link layer addressing and data decomposition methods according to the physical signal requirements of media and the type of data link layer protocol used. That is to say, the source MAC address and target MAC address are determined according to the requirements of media type, and the frame head and frame tail and FCS (error detection) are added<
2.
topology: in different network topologies, do we access media in a controlled or contention way. In the early Ethernet multi-channel access, we used contention mechanism. Contention, as the name suggests, is to scramble; Controlled is the mechanism of token ring, which is mainly based on the way of rotation<
3.
the working process of CSMA / CD:
4.
the working principle of ARP:
5.
the working principle of switch:
6.
conflict domain and broadcast domain: CSMA / CD is the abbreviation of carrier sense multiple access / collision detected, It can be translated into "carrier reconnaissance listening multiple access / collision detection" or "carrier listening multiple access with collision detection". Carrier sense means that each workstation on the network must have data transmission on the bus before sending data. If the bus is busy, the data will not be sent; If there is no data transmission (the bus is called empty), send the prepared data immediately. The so-called multiple access means that all workstations on the network use the same bus to send and receive data, and the data is broadcast. The so-called collision means that if there are two or more workstations on the network sending data at the same time, the signal will be mixed on the bus. If any workstation sends data at the same time, the signal will be generated on the bus. Mixed, no workstation can tell what the real data is. This situation is called data conflict or collision. In order to rece the impact of the conflict. In the process of sending data, the workstation should constantly detect whether the data it sends conflicts with the data of other workstations in the process of transmission, which is called collision detected. The working principle of CSNM / CD media access control method can be summarized as follows: listening before speaking, listening while speaking; In case of conflict, stop talking immediately; Wait for the moment, and then talk about it; Listening means monitoring and testing; It means to send data. Before sending data, monitor whether the bus is idle. If the bus is busy, it will not be sent. If the bus is idle, the prepared data is sent to the bus. In the process of sending data, the workstation sends the detection bus to check whether the data sent by itself conflicts. If there is no conflict, continue to send until all data is sent; If there is a conflict, stop sending data immediately, but send a jam signal to strengthen the conflict, so that all work sites on the network know that there is a conflict on the network. Then, wait for a predetermined random time, and when the bus is idle, resend the unfinished data.
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