Setting up Wide Area Network (WAN) serial connection management for your Cisco device is quite straight-forward. For this example, you connect two Cisco routers by using a back-to-back cable or DTC-DTE cable, emulating a service provider connection between the two devices.
Configuring your serial connection
In serial interfaces you need to make sure that clock rate and bandwith do match (changing clock rate does not automatically changes bandwith) Otherwise it could happen that your routing protocol does not take into account a link or sets the best route through the wrong link, because of bad settings in bandwith parameter. Hi all, can any body help us regarding serial link problem serial link detals are as follows Serial0/0/1 is up, line protocol is up Hardware is GT96K Serial Description:. NAGPUR AOBDC TO MUMBAI COB RIL Link 6. Internet address is 1.1.1.5/30. The Serial Wire Viewer provides a low cost method of obtaining information from inside the MCU. The SWO can output trace data in two output formats, but only one output mechanism may be selected at the same time. The 2 defined encodings are UART and Manchester. The current J-Link implementation supports only UART encoding.
The basic configuration of a serial connection is no different than the other types of connections you enter Interface Configuration mode, set the IP address, and remove the shutdown command. Here is the code on Router1 to setup the required connection.
Configuring serial link protocols
With the basic IP configuration out of the way, you are ready to implement the serial link protocol or encapsulation protocol. You can choose from either High-Level Data Link Control (HDLC) or Point to Point Protocol (PPP), which are encapsulation protocols used to format data to send across the wire. When you are sending data over a serial link, your data is encapsulated using a serial link protocol. Both ends of the connections must support and implement the same protocol.
HDLC does not support authentication. Because of this limitation and the compatibility issue, most people tend to implement PPP.
Working with HDLC
HDLC is an ISO standard, but that has not stopped vendors from putting their own spin on the implementation, which means that its implementation is somewhat vendor-specific.
HDLC is the default serial link protocol implemented on Cisco routers, so with no other changes, this is the protocol you are likely to find in use. To ensure that the HDLC protocol to be used, and for you to see the command, run the following command:
Both ends of the serial link must use the same serial link protocol, so if one of your routers is using HDLC, it must be implemented on the other routers as well.
Working with PPP
PPP is an open standard supported by many vendors, and it tends to be compatible among the vendors. PPP is also link type independent, meaning it can run over many physical serial link types, and supports the following two types of authentication protocol:
PAP (Password Authentication Protocol): An authentication protocol that provides security by a username and a password that are transmitted in plain text when a connection is established between two hosts. This option is not the most secure one because it allows the authentication information to be captured by someone who may be capable of capturing data in-between your routers.
CHAP (Challenge Handshake Authentication Protocol): This protocol does not send the authentication information in plain text. When implementing CHAP, a secret password is configured on both routers, the same secret at both ends. This secret is then encoded by a mathematical function called a hashing algorithm, and the resulting value is called the hash value.
This hash value is sent over the network rather than the secret. A hash value is a unique value that can be duplicated only if a user knows the original secret value.
Make note of the username created in the preceding commands; this username matches the hostname of the router that will be connecting to Router1. The password assigned to this account is the secret that will be used. On Router2, you need to create a Router1 account with a matching password.
K Line Serial Link Interface
Setting the clock rate
To finally get your system up and running, you need to set up the clock speed, which controls the speed at which data is sent over the connection in bits per second (bps). The DCE sets and controls the clock speed. So, in the case of a link from a service provider, the provider sets the clock speed, and when you connect to the external CSU/DSU, your serial port accepts the configuration.
In the case of a back-to-back cable, one of the routers plays the role of the DCE, and that device sets the clock speed for the connection. If you are implementing the same type of layout in a lab, check the cable and identify the DCE side of the cable; then implement the clock speed with a command similar to the following:
In this example, the clock rate is set at 64000 or 64 Kbps.
To find the clock rates that are available on your router, type clock rate ? when in Interface Configuration mode on your serial connection, as shown in this command example:
In telecommunication and data transmission, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels.
Serial communication is used for all long-haul communication and most computer networks, where the cost of cable and synchronization difficulties make parallel communication impractical. Serial computer buses are becoming more common even at shorter distances, as improved signal integrity and transmission speeds in newer serial technologies have begun to outweigh the parallel bus's advantage of simplicity (no need for serializer and deserializer, or SerDes) and to outstrip its disadvantages (clock skew, interconnect density). The migration from PCI to PCI Express is an example.
Cables[edit]
Many serial communication systems were originally designed to transfer data over relatively large distances through some sort of data cable.
Practically all long-distance communication transmits data one bit at a time, rather than in parallel, because it reduces the cost of the cable. The cables that carry this data (other than 'the' serial cable) and the computer ports they plug into are usually referred to with a more specific name, to reduce confusion.
Keyboard and mouse cables and ports are almost invariably serial—such as PS/2 port, Apple Desktop Bus and USB.
The cables that carry digital video are almost invariably serial—such as coax cable plugged into a HD-SDI port, a webcam plugged into a USB port or Firewire port, Ethernet cable connecting an IP camera to a Power over Ethernet port, FPD-Link, etc.
Other such cables and ports, transmitting data one bit at a time, include Serial ATA, Serial SCSI, Ethernet cable plugged into Ethernet ports, the Display Data Channel using previously reserved pins of the VGA connector or the DVI port or the HDMI port.
Serial buses[edit]
Many communication systems were generally designed to connect two integrated circuits on the same printed circuit board, connected by signal traces on that board (rather than external cables).
Integrated circuits are more expensive when they have more pins. To reduce the number of pins in a package, many ICs use a serial bus to transfer data when speed is not important. Some examples of such low-cost serial buses include RS-232, SPI, I²C, DC-BUS, UNI/O, 1-Wire and PCI Express. In IC, serial bus may be typically implemented by using multiplexer (which utilizes technique called multiplexing).[1]
Serial versus parallel[edit]
The communication links, across which computers (or parts of computers) talk to one another, may be either serial or parallel. A parallel link transmits several streams of data simultaneously along multiple channels (e.g., wires, printed circuit tracks, or optical fibers); whereas, a serial link transmits only a single stream of data.
Although a serial link may seem inferior to a parallel one, since it can transmit less data per clock cycle, it is often the case that serial links can be clocked considerably faster than parallel links in order to achieve a higher data rate. Several factors allow serial to be clocked at a higher rate:
- Clock skew between different channels is not an issue (for unclocked asynchronous serial communication links).
- A serial connection requires fewer interconnecting cables (e.g., wires/fibers) and hence occupies less space. The extra space allows for better isolation of the channel from its surroundings.
- Crosstalk is less of an issue, because there are fewer conductors in proximity.
In many cases, serial is cheaper to implement than parallel. Many ICs have serial interfaces, as opposed to parallel ones, so that they have fewer pins and are therefore less expensive.
Examples of architectures[edit]
- ARINC 818 Avionics Digital Video Bus
- Atari SIO (Joe Decuir credits his work on Atari SIO as the basis of USB)
- CAN Control Area Network Vehicle Bus
- ccTalk Used in the money transaction and point-of-sale industry
- CoaXPress industrial camera protocol over Coax
- DC-BUS communication over DC power lines
- DMX512 control of theatrical lighting
- Fibre Channel (high-speed, for connecting computers to mass storage devices)
- InfiniBand (very high speed, broadly comparable in scope to PCI)
- I²C multidrop serial bus
- MIDI control of electronic musical instruments
- RS-232 (low-speed, implemented by serial ports)
- RS-422 multidrop serial bus
- RS-485 multidrop multimaster serial bus
- SDI-12 industrial sensor protocol
- SONET and SDH (high speed telecommunication over optical fibers)
- SpaceWire Spacecraft communication network
- T-1, E-1 and variants (high speed telecommunication over copper pairs)
- Universal Serial Bus (for connecting peripherals to computers)
- UNI/O multidrop serial bus
- 1-Wire multidrop serial bus
See also[edit]
- High-Level Data Link Control (HDLC)
- Universal asynchronous receiver/transmitter (UART)
References[edit]
- ^'Circuit Implementation Using Multiplexers'. www.ee.surrey.ac.uk. Retrieved 2019-04-30.
High Speed Serial Link Interface
External links[edit]
- Serial Interface Tutorial for Robotics (contains many practical examples)