RJ45 network card interface 10/100 Base TX RJ45 interface is a commonly used Ethernet interface, supporting adaptive network connection speeds of 10 Mbps and 100 Mbps. There are two common types of RJ45 interfaces: DTE type used for Ethernet network cards, router Ethernet interfaces, etc., and DCE type used for switches, etc. We can call DTE "data terminal equipment" and DCE "data communication equipment". In a sense, DTE devices are called "active communication devices", while DCE devices are called "passive communication devices". When two devices of the same type are connected for communication using an RJ45 interface, a crossover cable connection must be used. This can be explained by the following definitions of RJ45 DTE type pins and RJ45 DCE type pins: RJ45 interface DTE type pin definition RJ45 interface DCE type pin definition. From the above figure, we can see that if two DTE type interfaces (or DCE type interfaces) are connected without crossing the connected pins, the pins that touch each other will be data receiving (sending) pins, and communication will inevitably not be possible. Additionally, it should be noted that some DCE type devices will automatically negotiate with the other end, and connections can be made using either crossover or parallel lines. RJ45 Ethernet cable plug, also known as crystal head, is made of eight cores and widely used for connecting network equipment between LAN and ADSL broadband internet users using Category 5 cables or twisted pair cables. In specific applications, there are two connection methods (line sequence) for RJ45 plugs and Ethernet cables, namely T568A line sequence (Figure 1) and T568B line sequence (Figure 2). The method for identifying the pin numbers of RJ45 Ethernet plugs is to hold the plug in hand, with one end of the 8 small gold-plated pieces facing upwards and the other end of the rectangular large mouth into which the Ethernet cable is inserted facing downwards. At the same time, place the one without the slender plastic card pin facing your eyes, starting from the first small gold-plated piece on the left, in order of pin 1, pin 2,..., pin 8. Figure 1: Schematic diagram of T568A line sequence connection method for RJ45 type network cable plug. The applicable scope of T568A line sequence is used in situations where network equipment needs to be cross connected. Cross connection refers to the different connection methods between one end and the other end of the network cable and the RJ45 network cable plug. One end is connected in T568A line sequence (Figure 1), and the other end is connected in T568B line sequence (Figure 2). This means that several network cables are crossed at the other end before being connected to the RJ45 plug. The applicable connection scenarios are:

1. Computer ← ->Computer, symmetrical equal network connection, that is, two computers can transmit data to each other through only one Ethernet cable connection;

2. Hub ← ->Hub;

3. Switch ← - → Switch.

As shown in Figure 1, the corresponding relationship between the pins of the RJ45 Ethernet plug and the color markings of the Ethernet cable is:

Plug pin number, Ethernet cable color

1-- Green and White

2-- Green

3-- Orange White

4-- Blue

5-- Blue and White

6-- Orange

7-- Brown White

8-- Brown

Figure 2: Schematic diagram of T568B line sequence connection method for RJ45 type Ethernet plug. The applicable range of T568B line sequence is suitable for T568B line sequence.

1、 Both ends of the direct interconnect network cable are connected according to T568B Computer ← ->ADSL Cat

2. ADSL modem ← ->WAN port of ADSL router

3. Computer ← ->LAN port of ADSL router

4. Computer ← ->Hub or Switch

2、 Connect one end of the crossover cable to T568B and the other end to T568A

1. Computer ← ->Computer, i.e. peer-to-peer network connection

2. Hub ← ->Hub

3. Switch ← - → Switch

As shown in Figure 2,

The corresponding relationship between the pins of the RJ45 Ethernet plug and the color markings of the Ethernet cable is:

Plug pin number, Ethernet cable color

1-- Orange White

2-- Orange

3-- Green and White

4-- Blue

5-- Blue and White

6-- Green

7-- Brown White

8-- Brown

For the straight through line (568B at both ends), the signal line is 1236 (orange green). Therefore, if some lines fail, the remaining lines can be used as backups and can still be used after repair, but the anti-interference performance may be reduced. In the general cabling standard, there is no separate mention of "RJ45", and all connector components must be 8-pin. Therefore, the collaboration and compatibility between RJ11 and RJ45 have not yet been documented. The name RJ stands for Registered Jack and is derived from Bell System's USOC (Universal Service Ordering Codes) code. USOC is a series of registered sockets and their wiring methods developed by Bell Systems for connecting users' devices to public networks. FCC regulations control the application of this purpose. The FCC (Federal Communications Commission), on behalf of the US government, has issued a document specifying RJ11. RJ11 is the generic name used for connectors developed by Western ElectricCo. Its appearance is defined as a 6-pin connecting device. The original name was WExW, where x represents' active ', contact or needle. For example, WE6W has all 6 contacts numbered 1 to 6, WE4W interface only uses the outermost two contacts (1 and 6) of the 4-pin, and WE2W only uses the middle two pins. For RJ11, the information source is contradictory, it can be a 6-pin connector with 2 or 4 cores. Even more confusing is that RJ11 is not only used to represent 6-pin connectors, but also refers to the 4-pin version. RJ45 interface is commonly used for data transmission, with the most common application being network card interface. RJ45 is a type of connector with various types of connectors (for example, RJ11 is also a type of connector, but it is used for telephones); RJ45 heads are divided into two types based on the sorting of wires: orange white, orange, green white, blue, blue white, green, brown white, and brown; Another type is green white, green, orange white, blue, blue white, orange, brown white, brown; Therefore, there are two types of wires that use RJ45 connectors: straight through wires and crossover wires. The 10/100 Base TX RJ45 interface is a commonly used Ethernet interface that supports adaptive network connection speeds of 10 Mbps and 100 Mbps. There are two common types of RJ45 interfaces: DTE for Ethernet cards, router Ethernet interfaces, and DCE for switches. We can call DTE "data terminal equipment" and DCE "data communication equipment". In a sense, DTE devices are called "active communication devices", while DCE devices are called "passive communication devices". When two devices of the same type are connected for communication using an RJ45 interface, a crossover cable connection must be used. This can be explained by the following definitions of RJ45 DTE type pins and RJ45 DCE type pins: RJ45 interface DTE type pin definition RJ45 interface DCE type pin definition. From the above figure, we can see that if two DTE type interfaces (or DCE type interfaces) are connected without crossing the connected pins, the pins that touch each other will be data receiving (sending) pins, and communication will inevitably not be possible. Additionally, it should be noted that some DCE type devices will automatically negotiate with the other end. In this case, the connection can be made using a crossover or parallel cable. The RJ45 type network cable plug, also known as a crystal head, is made of eight cores and is widely used for connecting network equipment between LAN and ADSL broadband internet users using Category 5 cables or twisted pair cables. In specific applications, there are two connection methods (line sequence) for RJ45 plugs and Ethernet cables, namely T568A line sequence (Figure 1) and T568B line sequence (Figure 2). The method for identifying the pin numbers of RJ45 Ethernet plugs is to hold the plug in hand, with one end of the 8 small gold-plated pieces facing upwards and the other end of the rectangular large mouth into which the Ethernet cable is inserted facing downwards. At the same time, place the one without the slender plastic card pin facing your eyes, starting from the first small gold-plated piece on the left, in order of pin 1, pin 2,..., pin 8. Figure 1: Schematic diagram of T568A line sequence connection method for RJ45 type network cable plug. The applicable scope of T568A T568A line sequence is used in situations where network equipment needs to be cross connected. Cross connection refers to the different connection methods between one end and the other end of the network cable and the RJ45 network cable plug. One end is connected in T568A line sequence (Figure 1), and the other end is connected in T568B line sequence (Figure 2). This means that several network cables are crossed at the other end before being connected to the RJ45 plug. The applicable connection scenarios are:

1. Computer ← ->Computer, symmetrical equal network connection, that is, two computers can transmit data to each other through only one Ethernet cable connection;

2. Hub ← ->Hub;

3. Switch ← - → Switch.

As shown in Figure 1, the corresponding relationship between the pins of the RJ45 Ethernet plug and the color markings of the Ethernet cable is: plug pin number, Ethernet cable color

1-- Green and White

2-- Green

3-- Orange White

4-- Blue

5-- Blue and White

6-- Orange

7-- Brown White

8-- Brown

Figure 2: Schematic diagram of T568B line sequence connection method for RJ45 type Ethernet plug. Applicable range of T568B T568B line sequence

1、 Both ends of the direct interconnect network cable are connected according to T568B

1. Computer ← ->ADSL modem

2. ADSL modem ← ->WAN port of ADSL router

3. Computer ← ->LAN port of ADSL router

4. Computer ← ->Hub or Switch

2、 Connect one end of the crossover cable to T568B and the other end to T568A

1. Computer ← ->Computer, i.e. peer-to-peer network connection

2. Hub ← ->Hub

3. Switch ← - → Switch

As shown in Figure 2, the corresponding relationship between the pins of the RJ45 Ethernet plug and the color markings of the Ethernet cable is: plug pin number, Ethernet cable color

1-- Orange White

2-- Orange

3-- Green and White

4-- Blue

5-- Blue and White

6-- Green

7-- Brown White

For the straight through line (568B at both ends), the signal line is 1236 (orange green). Therefore, if some lines fail, the remaining lines can be used as backups and can still be used after repair, but the anti-interference performance may be reduced. In the general cabling standard, there is no separate mention of "RJ45", and all connector components must be 8-pin. Therefore, the collaboration and compatibility between RJ11 and RJ45 have not yet been documented. The name RJ stands for Registered Jack and is derived from Bell System's USOC (Universal Service Ordering Codes) code. USOC is a series of registered sockets and their wiring methods developed by Bell Systems for connecting users' devices to public networks. FCC regulations control the application of this purpose. The FCC (Federal Communications Commission), on behalf of the US government, has issued a document specifying RJ11. RJ11 is the generic name used for connectors developed by Western ElectricCo. Its appearance is defined as a 6-pin connecting device. The original name was WExW, where x represents' active ', contact or needle. For example, WE6W has all 6 contacts numbered 1 to 6, WE4W interface only uses the outermost two contacts (1 and 6) of the 4-pin, and WE2W only uses the middle two pins. For RJ11, the information source is contradictory, it can be a 6-pin connector with 2 or 4 cores. Even more confusing is that RJ11 is not only used to represent 6-pin connectors, but also refers to the 4-pin version. Different standards and sizes are distinguished due to the different sizes of the two (RJ11 is a 4-pin or 6-pin connector, RJ45 is an 8-pin connector). Obviously, RJ45 plugs cannot be inserted into RJ11 sockets. On the contrary, it is physically feasible (RJ11 plugs are smaller than RJ45 sockets), which leads people to mistakenly believe that the two should or can work together. Actually, it's not like that. It is strongly recommended not to use RJ11 plugs for RJ45 sockets. Because RJ11 is not internationally standardized, its size, insertion force, insertion angle, etc. are not uniformly designed according to international standard connector requirements, so interoperability cannot be guaranteed. They even cause damage to both. Due to the RJ11 plug being smaller than the RJ45 jack, the plastic parts on both sides of the plug will damage the metal pins of the inserted jack.

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