why we are using serial port in routers?

Question

what is the purpose of serial port?.
when serial port is beneficiary and why?

Answer 1

For information on configuring an Asynchronous Transfer Mode (ATM) interface, refer to the "Configuring ATM Access over a Serial Interface" chapter in the Cisco IOS Wide-Area Networking Configuration Guide.



For hardware technical descriptions and information about installing interfaces, refer to the hardware installation and configuration publication for your product. For a complete description of serial interface commands used in this chapter, refer to the "Interface Commands" chapter of the Cisco IOS Interface Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online

What are Serial Ports?



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Serial ports are a type of computer interface that complies with the RS-232 standard. They are 9-pin connectors that relay information, incoming or outgoing, one byte at a time. Each byte is broken up into a series of eight bits, hence the term serial port.



Serial ports are one of the oldest types of interface standards. Before internal modems became commonplace, external modems were connected to computers via serial ports, also known as communication or "COM" ports. Computer mice and even keyboards also used serial ports. Some serial ports used 25-pin connectors, but the 9-pin variety was more common. Serial ports are controlled by a special chip call a UART (Universal Asynchronous Receiver Transmitter).



Serial ports differ from 25-pin parallel ports in that the parallel ports transmit one byte at a time by using eight parallel wires that each carry one bit. With data traveling in parallel, the transfer rate was greater. A parallel port could support rates up to 100 kilobytes per second, while serial ports only supported 115 kilobits per second (kbps). Later, enhanced technology pushed serial port speeds to 460 kbps.



In traditional computers, serial ports were configured as follows:



Serial Ports Interrupt Memory Address

COM 1 IRQ 4 0x3f8

COM 2 IRQ 3 0x2f8

COM 3 IRQ 4 0x3e8

COM 4 IRQ 3 0x2e8





Devices configured to use serial ports COM 1 and COM 3 could not be active at the same time, as they shared interrupt IRQ 4. The same was true of COM 2 and COM 4 port devices. Often this led to manually reconfiguring the serial ports, which frequently caused more trouble than it was worth and posed a special challenge for the dyslexic!



Today, serial ports are mainly used for dial-up modems and current operating systems handle configuration automatically. Newer, faster technologies of USB (Universal Serial Bus) and Firewire have otherwise replaced both parallel and serial ports. USB supports speeds from 1.5 megabits per second to 60 megabytes per second. Firewire boasts transfer rates between 100 and 400 megabits per second.

Answer 2

It's not so typical anymore. You are right it is slow, but for a long time it was the only way to do point-to-point connections. These days private WANs (managed VPNs) are more common. Serial is still out there, and it is a lot faster than the cable you are using to plug those two routers into each other, and a lot of the configuration steps around it are the same for other types of connections, particularly the idea overall of point-to-point connections. It will make more sense the further you go, it's like learning the alphabet; less something you think about every day but the principle underpins a lot of what you do that is so much faster and more complicated ;-)

Answer 3

In most network equipment like routers, the serial port may be used for console dump purposes. You may define certain levels of logging and what should be "dumped" to the serial port which may be attached to a DTE (Data Terminal Equipment) or printer.

This way you can make sure that the intruder doesn't have the chance to "blur his trails" after hacking your equipment in a temptative to difficult the forensic analysis

Answer 4

Serial port is use for the Printer Networking!