Expert Answer: Data Center cabling Project 10 Questions

In this article, we will introduce users in the data center cabling project encountered 10 problems and Wu, Zhang Yi and Chen Yutung and other experts to answer.

1. Q: On the construction of cable across long distances

I encountered this situation in the unit, the office building is too wide, and the Internet access point is at the far left of the building, to achieve each floor has Internet access, but also fast, how to solve?

Chen Yutung: The balance twisted pair is 100 meters in support of data application, which is defined by international standards. The transmission of network signals over a distance of more than 100 meters will depend on the performance margin of the cabling system, the performance margin of the network equipment, the construction of the site and other uncertain factors, not a quantified index, can not be guaranteed. According to the case you mentioned, the standard practice is to set up 2 telecommunication rooms on one floor, the horizontal cable division area connects to the corresponding telecommunication room, guarantee the horizontal link (from the wiring frame to the information outlet) length not exceeding 90 meters.

Of course, you can also use high-performance level, good quality cables and modules to do direct point-to-point connection (more than 100 meters), but this line on the network application support is not guaranteed, that is, may be able to support xDSL or 10base-t signal, but may not support a higher rate.

Wu Jian A: Wiring design standards need to be followed, if too long, you can consider in the middle of the relay, such as a switch or hub to connect the two-segment network cable. Don't take the risk of being too long, which leads to uncertainty in network communication.

2. Q: I would like to ask an expert our company has a network port is from the floor switch, in the test after the switch, the screen, and from the floor of the switch in the line, the computer is no problem, but the problem is that the package can not receive a packet, changed a few computers are useless. Would you like to know if the connector between the main switch and the floor switch is broken during threading?

Chen Yutung: It appears that there may be a problem with the line, provided that the switch port and this computer port are able to send and receive packets on other lines. It is recommended that you use the wiring tester for the transmission channel performance test, that is, including both ends of the jumper, both ends of the connector (wiring racks and information outlets) and the laying of the cable, test standards according to the actual situation of the choice of 5E class or 6 categories. Also confirm that the jumper used satisfies the t568a/b line order standard.

3. Q: What are the special requirements for fiber channel wiring in the data center room?

Zhang Yi A: In the data center of the computer room cable channel is mainly used in the million network, the selection of attention to the following points: Transmission distance: OM3 multimode fiber for the 300m-550m, Single-mode optical fiber for the 10-40km; fiber-optic connection devices and adapters for SC, LC or according to the network device port type selection; If the use of open cable Bridge laying mode of optical fiber cable to achieve the corresponding fire level (A or B-class room), Optical wiring module settings (such as the top of the equipment cabinet, open type Bridge, wiring header cabinets and a variety of wiring cabinets).

4. Q: I would like to consult the experts: our Company A total of 3-storey buildings, each layer has a computer 80-100, each layer of computer distribution area of more than 300 square meters. I want to consult, like this case, how can I do to relatively simple and effective completion of network cable layout. At present, the more vague plan is to place a 3-layer switch in the central area of each layer, then connect 3 switches through the PC server to realize network sharing, and then internet access via routers. I don't know if that's okay.

Zhang Yi A: A converged switch should be set up on a 3-tier switch based on the switching network architecture, pooling the switch access server as a data resource sharing platform for network users, and then pooling the switch to connect to the Internet via a compatible router. Here are some points to note:

Wiring network architecture adapts to the structure of computer network; The setting of the floor wiring to note that the horizontal cable does not exceed the 90m length, the wiring system rank conforms to the Ethernet switch transmission bandwidth, recommends that the level uses the Ultra 5 class or 6 class cabling system, the backbone uses multimode optical fiber (OM3), and configures the corresponding wiring module, Should design a more detailed wiring system structure diagram, and network facilities to express the interoperability relationship.

5. Q: After the network wiring is done, how to accept?

Zhang Yi: The specific acceptance method please refer to gb50312-2007 "Integrated wiring system Engineering Acceptance Code", acceptance note the following points:

All information points to do permanent link testing, the connection model according to the specifications;

The test index project according to the Wiring System support network (such as hundred trillion, gigabit, Wan Shao, Ethernet network) to determine, specifically see the specification index parameter table;

Determine the function and accuracy of the test instrument;

The test result should be typed into the document to save;

The quality of the project should be judged by the standard (qualified or unqualified).

The specification has a more detailed description and can be raised if there are problems.

6. Q: Ask the Gigabit network cable problem: We are playing lines are in accordance with a or B standard to do. But look at the data said Gigabit network cable has its own line order, the problem came out. Can a line of a or b be used to run thousands of megabytes? Gigabit is the use of 8 lines working together. If it is Gigabit Half-duplex, is it necessary to use only 4 wire? Poe power supply is used to the network cable in the 4 lines to transmit electricity, then hundred trillion lines to say, but the thousand trillion is using 8 lines to transmit the signal, is not Gigabit port mode can not achieve Poe power supply it?

Zhang Yi Answer: Under normal circumstances, according to the wiring diagram of B card to connect network cable, but a project in the way of the card line using the same standard, not a, B mixed. Line-playing standards depend primarily on the type of network device port, in general, 10M, 100M, 1000M network connection by standard wiring, to the million network such as the use of shielded wiring, there will be a special connection, the specific combination of manufacturers to provide the installation manual, construction; Gigabit network basically four pairs of lines are all adopted, And it's a two-way way of working. There are two types of Poe power supply: One is two pairs of wire transmission information, two pairs of lines of power supply; Poe power supply mainly depends on the function of network equipment, transmission line is no problem.

Chen Yutung A: Gigabit Ethernet to follow the IEEE802.3AB standards, to support the enhancement of more than five cabling system, if your wiring system components and the entire channel are in line with the CAT.5E standards, whether in accordance with a or B standard can support gigabit. Gigabit Ethernet is full duplex running on the 4 pairs of lines, the current market does not see Half-duplex gigabit network equipment.

Poe is divided into endpoint and mid-span two modes, endpoint is powered by the switch port, End-span is in the middle of the line load power, now both models are supported on the data line on the load power signal, the market on the two models of the gigabit products have.

Wu Jian: There are two kinds of Gigabit interface: T and 1000BASE-TX. They all use 4 pairs of lines, but in different ways.

1000BASE-TX, two pairs of 500M are sent, and the other two 500M receive, so it can achieve 1000M full duplex (2000M throughput). This interface must be six types of cables to support.

1000baset-t, is four to send and receive 250M, also can do 250*4,1000m Full-duplex transmission. This interface is available on both the Super five line and the six cable.

The interface of most devices now is T. The T device interface cost is slightly higher than the 1000BASE-TX, because T requires the device interface to have crosstalk cancellation technology.

7. Q: In the access network this piece, CATV development future How? Is there a trend to replace ADSL?

Zhang Yi: CATV is generally used HFC fiber copper cable hybrid access technology, it can support the cable TV signal, voice, data and other information transmission. It can also achieve the integration of business network, but from the current state of the industry-related regulations and policy provisions: CATV network mainly applies cable television networks. ADSL is also a kind of copper access technology, it can also achieve multiple services access, but at present it is mainly used in voice and data services, telecommunications operators are a broadband access mode. All access technology such as the current use of epon can achieve business integration, so technically can be achieved, all kinds of technology has its own characteristics, can not completely say who can replace who.

8. Q: Expert Hello, in a study time to see a noun "short link resonance." What exactly is called short link resonance (resonance link)?

Wu Jian: This is a very good question, involving cabling design standards and product optimization.

The short link resonance you mentioned is that when the link is shorter (less than 15 meters), the superposition caused by unbalanced signal or noise signal in the link leads to communication failure (the more easily the signal reflection between the links is shortened). We all know that the permanent link is less than 90 meters, but the standard also requires more than 15 meters, so you can avoid the "short link" problem. That is, link testing often fails when the link between two wiring racks or modules is shorter than 15 meters. This phenomenon is frequently seen in Super five and six types of cable systems, and we usually have a short link problem.

However, the problem is not so terrible, some manufacturers to do their own products optimized processing, or signal compensation technology, so that in short link, can also achieve the corresponding performance. For example, it can be used at 7 meters or even shorter. At the same time, tester manufacturers are also optimizing the test adapters to suit the changes in cable products.

All you need to know is that the link is not as short as possible.

9. Question: About Access networking

There's a lot of access to the Internet, but there's no way to find a book that's completely clear. Can the experts sum it up? from dial-up to optical access and other access methods, to a variety of access to the case of the actual operation manual or program.

The line connects the net. Connect the networks of different plots to form a local area network. What are the ways?

Question 1: If I applied for a SDH/DDN/MSTP line access in the telecom, then in another place I use Netcom's SDH/DDN/MSTP can be connected to each other?

Zhang Yi A: 1 about LAN access to the computer Internet is a wide variety of the current general user mainly adopted the following:

The Outlet optical port (10m/100m/1000m) of the backbone Ethernet switch directly from the LAN is connected with the wide area network after the fiber distribution frame of telecom or other (such as technology, campus network, etc.) through Single-mode optical cable.

Using the export port of Backbone Ethernet switch plus the router that accords with corresponding communication service network interface equipment, we should consider the need of satisfying the export transmission bandwidth, and currently adopt 2M (E1) based access mode.

Telecom operators provide ADSL, EPON, Wireless broadband access and other means, the same to meet the export bandwidth as the main basis for operators to interface bandwidth requirements. Access to the internet via a cable TV network (HFC) user terminal device or set-top box. The simplest is to dial the Internet by using a telephone line plus a modem.

Of course there are many kinds of access network technology. People's post and telecommunications publishing house has a special introduction to access network technology books, in addition the communications industry has issued access network system engineering construction related norms, these are the technical documents from which can be learned.

Question 2: If it is through the dedicated line and not through the Exchange network, the general should use the same telecommunications operators of the sdh/mstp/ddn/equipment, but also may be a certain telecommunications operators and some private network of SDH interoperability, to provide users with off-site services. In the specific project can negotiate with operators.

10. Q: I would like to ask the entire network has been cloth line, testing all through, but after a period of time, connected to the PC to show the network disconnected, with the detection of the wire detector all pass, this is how it?

Chen Yutung A: The general wiring of the acceptance should use professional wiring test equipment, and should not adopt a simple pass-and-break tester. Professional equipment in addition to breaking and line order, but also detect insertion loss, crosstalk, loss, delay and other electrical performance parameters, to help you determine the wiring system installation is qualified.