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how to select and purchase the suitable network card

一.Classification of Network Cards
Here ,we just mention wired Ethernet network card , not involved in other kinds like Token ring network card、Token bus network card、FDDI network card, etc.
Network cards can be divided into:
1.By transmission medium: RJ45 network card (can be also called copper network card)、fiber optical network card;
2.By transmission rate:100Mbps network card、1000Mbps network card、10Gbps network card ;
3.By slot of host computer: PCI (32Bit) network card、PCI-X(64Bit)network card、PCI-E(×1\×4\×8\×16)network card;
4.By number of ports: Single-port network card、Dual-port network card、Four-port network card;
5.By operating environment: Workstation(desktop)network card、sever network card;
6.By wavelength: Multi-mode network card , Single-mode network card.
二.guides on how to select fiber network card
1.Pay more attention while using fiber optic network than copper network card, the speed rate of copper network card is auto-negotiation whereas fiber optic network card is fixed. Therefore, when in use, the below three terms must be satisfied:
(1)Transfer rate of both ports must be the same, i.e speeds of both ports are 100Mbps or 1000Mbps; if speed of one port is 100Mbps, the other port is 1000Mbps, that can’t be connected;
(2)Both ports of fiber optical wavelength must be the same, i.e. both ports are 850nm(multi-mode) or 1310nm(single-mode);
(3)Selecting corresponding fiber optical cabling according to wavelength, selecting 62.5/125-micron-radius multi-mode fiber optical cable (generally it’s red) at 850nm; selecting 9/125-micron-radius single-mode fiber optical cable(generally it’s yellow) at 1310nm.
2.connector of fiber optical network card has more specifications than copper network card ,it has LC,SC,FC,ST connector ,etc. In general, LC and SC port are more frequently-used. Therefore, we should select paired fiber optical cable according to both connectors’ specifications, such as LC-LC, LC-SC,SC-SC, etc.

How to select high-quality network card

(1) PCB Craft
Superior network card adopt multi-layer Solder Coating PCB while inferior network card generally adopt non solder coating or two-layer PCB. PCB layers and crafts impact the stability of network card directly. In general, 100Mbps network card comprise of two layer PCB whereas 1000Mbps network cards comprise of four to six layers, server network card need 6 to 8 layers at least. PCB will mark out the layers from qualified factories. 

(2) Welding Procedure

 Superior network card’s welding spots in PCB are homogeneous and clean whereas inferior network cards are not even, some of them are made by hand with small air holes or overlying or faulty soldering. Good welding crafts ensure the stable data transmission.
 PS:LR-LINK products" welding spots are homogenous and clean.

(3) Wiring & Components Layout
Superior network cards should be in compliance with the minimum return circuit area between signal line and ground to reduce the possibility of disturbance among signals. Signal wire should abide the industry benchmark with 45 degree Angle especially the Pairs of difference line must be equal length parallel. The length of pairs of line should be within 10 miles. Inferior network card wire is out of order and at random. This lead to signal transmission volatility and make the PC frequency fluctuate and working unstable. A lot of data packet lost and network interrupted.
PS:Superior network card’s layout is tidy with distinct function while the components of inferior network card lay at random with long wire.  

(4)Selection of Component

Superior network cards basically adopt SMT components, given SMT components are much more reliable than plug-in units and that SMT components can reduce volume of electro circuit , enhance effect of heat dissipation. As SMT components adopt wave soldering on soldering craft, this ensures the quality of soldered dot.      

Power supply of superior network cards adopts formal manufacturer’s power supply control chip as stable power supply is a guarantee of network cards’ stable working.

PS: Power of inferior network card is commonly supplied by computer motherboard. Thus, network card will be susceptible to motherboard power supply’s wave, arising network interruption, unrecognizing network card while starting, etc. It’s easy for users to recognize the power supply method and recognize if the network card is good.
(5)Golden Finger Craft
Golden finger is the contact part of network card and motherboard. Superior network card should select gold plating, the thickness of gold plating is much more 3-5mil than the inferiors, and the surface is golden yellow. However, inferior network cards select copper plating .That’s easily color-lost, rusting and surface-whitish. All that will make network card bad connect with motherboard.
LR-LINK brand network cards adopt 6-layered to 8-layered PCB , superficially tin-spraying craft. Thickness of immersion gold is as much as 5mil.We put a strict requirement on differential pair trace routing, and its length is limited in 5mil; good component layout ensures the whole PCB concise and decent. All the components are from formal original material factories that ensure the stability of power supply by entirely selecting American TI、LTC power supply chip .All of the finished products must go through 24-hour live working maturing under70 degrees, then again strict test method. Thus , these make sure the high stability and reliability ,the qualification rate of each product is up to 100%.

LR-LINK brand network adapter selection classification, Broadcom and Intel two solutions
Fiber NIC for server :
Broadcom 1G (PCIe x4): LREC9710PF/LX; LREC9712PF/LX
Broadcom 10G (PCIe x8): 9812AF-2SFP
Intel 1G (PCIe x4): 9702PF/9702EF/9704HF (SFP)
Intel 10G (PCIex8):LREC9802AF/ 9802BF (SFP+)

Fiber NIC for Desktop series:
PCI 100M: LREC7010PF/7020PF (single-mode or multi-mode)
PCIe x1 100M: LREC9010PF/9020PF/9030PF /6210PF (single-mode or multi-mode)
PCI 1G: LREC7210 PF or SFP (single-mode or multi-mode)
PCIe x1 1G: LREC9210/9220PF or SFP (single-mode or multi-mode)

RJ45 NIC for server series:
Broadcom 1G (PCIe x4): LREC9701PT/9712PT
Intel 1G (PCIe x4): LREC9700PT/9702PT/9722PT/9702ET/9704HT

More products for your choice:   http://www.lr-link.com/product.asp