by R. K. Bloom

Test network equipment SMC 802.11b standard

Test network equipment SMC 802.11b standard

A few words about wireless networks and standards

Wireless networks have a lot of advantages over wired networks. First of all, its easy to connect, and there is no need to stretch the wires to each new workplace. In addition, properly organized wireless network allows you to make mobile employees throughout the office – that is, owner of a laptop or handheld computer with the appropriate adapter, can easily move around the premises, along with a working network resources and the Internet.

The standard 802.11b wireless networks can not be called something new, but in Russia, where even local networks enmeshed are not many places, it still remains bizarre. Not many shops can be found on the shelves of PC Card Adapters 802.11b, not to mention USB and PCI versions. In addition to the actual 802.11b, there are several standards for wireless networks. We will not address the very very old version 802.11, intended for home networking or service provider, and only remember two key competitor 802.11a and 802.11g.

Both of these standards provide greater data transfer speed (54 Mbit / s compared to 11 megabits per second for 802.11b), and operate at frequencies of 5 and 2.4 GHz respectively. Note that the frequency range of 802.11g is identical to that of 802.11b, and in fact, that a new format can be considered the heir 802.11b. As for 802.11a, the equipment of the standard used in Russia and officially can not be sold, as the range of frequencies in the 5 GHz band is reserved, and the equipment simply can not be certified.

What is so attractive 802.11b?

With a relatively low price, you get a device that can operate at distances up to 450 meters in open areas at a reasonable rate. Of course, these half a kilometer more purely theoretical value, and squeeze them to 11 megabits per second without the use of expensive amplifiers is virtually impossible. 802.11b standard can transmit data at speeds from 1 to 11 Mbit / s, varying the speed of the conditions of communication, power settings, and displayed in the driver options.

Today we test the network adapters and SMC2602W SMC2632W 802.11b standard from the company SMC Networks.

Key Features

EZ Connect Wireless PCI adapter from the company SMC, and this is precisely the name of the device has a serial number SMC2602W, supports half-duplex Ethernet connections with a capacity of 1, 2, 5.5 or 11 Mbit / s. It is fully compatible with 2.4 GHz DSSS CSMA / CA, as well as prescribes the IEEE 802.11b, as indicated by its number FCC ID. All of this fits the SMC2632W – PC Card version with fully identical characteristics.

PCI device is similar in principle work on a card reader for flash cards. In fact, you install a PCI slot device that adds to your desktop such as PC Card, like laptops. The adapter is installed immediately and rigidly fixed price PC Card SMC2632W, which if desired can be extracted and used with a laptop. Board size seemed quite acceptable to us, but yet, they can be reduced and, in such a small number of parts. There are no indicators on the PCI card does not, except one, which is located on the PCMCIA unit. Yes, and do not need them.

On the PCI card is a chip from PLX Technology PCI9052. Even if youve seen here are two different devices, and glad at once to disappoint you, you will not get them at the price of one! You will have a choice: PCI or PCMCIA. In the case of separation of PC Card adapter from PCI block you do not lose the warranty of, and for ease of installation, it is best to remove PCMCIA component.

It should be noted that there is no PCMCIA adapter socket for an external antenna, that is, you can not connect to the system of active power in order to improve communication in the network at large distances or in difficult conditions, well-insulated buildings.

The set comes: the card itself, with an installed PCMCIA part, instruction in the paper version in five languages, a CD with documentation and drivers, as well as beautiful box in which everything is packed.

Installation

The first problems began at a time when we tried to insert a PCI card into the computer – we just could not install the adapter in our case. Interfered with PCMCIA card, prevented the bolts on the motherboard and other components. In total, we spent about half an hour to install. I had to choose a PCI slot, next to which there were no superfluous elements and circuit boards, unscrew the bolt to the motherboard, located near and interferes with the installation. Much depends on the case. On the other machines we have not experienced such torment. In any case, insert the card into the body can, its only a matter of time and perseverance.

Later in touch with distributors SMC cards in Russia, we learned that they could without too much trouble to remove PCMCIA card from the PCI adapter, and for us it is not deprived of a warranty on the equipment. What is the same one who knew that the inscription that says “do not remove the sticker,” should not be taken seriously. Since installing the PCMCIA adapter, no problem, it took just paste it into the slot laptop.

Setting

Rather than complete drivers recorded on the CD, we decided to use the services of the Internet, and download from the site of the new versions of the firmware and driver. After turning on the computer with the card installed, we were offered several options for installing the driver, we decided to do everything manually.

After that, there is another network card in Device Manager and its time to configure it.

Status

  1. In the “Status” you can see the current state of wireless connection: the MAC address of network card partner, transfer rate, channel, current capacity, call quality and signal strength.
  2. Konfigurtsiya

Tab “Configuration” allows you to change parameters such as profile name, network ID, network type, channel, connect and transfer speed. Profiles can be useful when using multiple connections where each name has its own profile of the network settings. The network name is used to when there are multiple wireless networks your computer is connected to your. More information can stay on the type of network. Here you should choose the mode in which the network adapter will work: Peer-to-Peer for direct connection to another network adapter or Access Point to connect to an access point.

Traditionally, the standard for WLAN adapter 802.11b, it is possible to manually select the transmission speed (11Mbps / s, 5.5 Mbit / s or automatic selection of 2.1 Mbit / s) and the fully automatic mode, in which the card and drivers themselves choose the best speed, coordinating with the level of interference, signal quality and power settings, PC Card adapter, as well as other conditions.

Security

Since the device uses a radio broadcast data, then the problem becomes very relevant for their protection. Agree, it is difficult to intercept data transmitted within the closed wired network. As to the radio, it is easily caught. In order to intercept the radio and read it more difficult to use so-called WEP-encryption with a 64-bit or 128-bit key.

SMC cards have a basic set of security – there is a choice of 64 or 128 bit encryption keys can be entered either as ASCII text or hexadecimal values, the keys themselves can be generated from the specified password. To do this, you can simply switch to create a key with a password, enter your password and click “Apply” button. Automatically generated four keys, each of which can be selected for use at the moment.

Keys can not be saved to a file, so you better write their values ??to later be able to call them on all devices.

It should be noted that when you turn off WEP, and then you turn the keys are not stored, and must be reentered.

The last tab you can see the version of the driver, configuration utility, firmware version and MAC address of the adapter.

Capabilities

The device can operate in two modes: Ad Hoc and Infrastructure. In the first case, the wireless network will consist of only a few computers with wireless network adapters. All they need to be configured to use one channel. This mode is useful for creating a home network or small office.

Ad Hoc mode

In the second mode, you will have access to the wired network from wireless. Generally, a network that combines both wired and wireless devices is called Infrastructure. In its simplest form it can be created from multiple computers with wireless network adapters and access points connected to the wired LAN. In this configuration, you can access any computer on the network, no matter whether it has a wireless or wired connection.

This mode not only allows you to interact with wireless and wired network segments, but, when using multiple access points, increases efficiency, but also the radius of the network (in the case when you are placed on an office building around a consistent set of access points). In this configuration, mobile users can communicate with each other, as well as work with databases stored on corporate servers.

Performance

Well, to test performance. To begin with, that we were a little disappointed with the system search for “pair” when we decided to test the adapters in the building a short distance from each other at a weak signal. In this case, the driver showed the rate of 2 Mbit / s, but the MAC address of the “pair” the adapter all the time change. And that has upset – even a short distance adapters are sometimes lost, in this case, was indicated MAC address “pair” devices “44 44 44 44 44 44.” What is it and why it happened remains a mystery to us. And another mystery, which also can not be explained – why, when a weak signal when the distance was clearly less than 35 meters, when searching for the second adapter was fine, its MAC address is displayed, the speed was set 2 Mbit / s, then why the MAC address -then suddenly changed to an unknown to us. And continued to change the address independently. In place of the test, this rate was free, and devices operating in this band was not. That is, when a weak signal you may encounter with the inexplicable behavior of the card or driver.

Testing was conducted on the following configurations:

The sender and the recipient:

AMD Duron processor 750

Memory 256 MB SDRAM

Adapter SMC2602W

The operating system is Windows 2000 with SP3

A client with a PCMCIA adapter:

An Intel Pentium III 750

Memory 256 MB SDRAM

Adapter SMC2632W

Operating system Windows XP with SP1

Tests were carried out under the following conditions: a rigid fixed-bandwidth 11 Mbit / s and 2 Mbit / s using the software NetIQ Chariot.

Test 1

The results obtained at 11 Mbit / s are shown in the chart below. It should be noted that the results were not obtained at the first start Chariot. In fact, there was a problem during long-term tests. For example, a ten-minute attempt to test the capacity of the first attempt failed – Chariot gave an error about the connection status some time after launch. If you try to figure out whats going on, it was found that the previously linked to each other cards were lost, and instead of MAC address paired device in the status window displays the addresses and consists only of numbers “4″, and the test stopped and gave an error.

On this chart is not as clearly visible difference, however, below we give a graph of the relative performance difference:

Transfer rate when you turn on a 128-bit WEP is reduced by about 3%, which we considered negligible. Such a decrease was observed as the PCI version, and PCMCIA. The speed of the PCI and PCMCIA adapters same versions differ by less than 5%, which may well be attributed to measurement error, although it is more visible as low bandwidth mode using WEP, and without it. This suggests that when using WEP at a speed of 11 Mbit / s, encryption is the bottleneck. Lets see what happens at lower speeds.

In the last of the above results a low bandwidth can be justified by the low-bandwidth, established at the beginning of the test. In all tests have been seen falling throughput. However, they were of short duration.

Testing bandwidth

To do this, we ran the script “throughput” for measuring bandwidth by changing the amount of data for each transmission 100 000 200 000 bytes, and with different number of repetitions.

Average throughput turned out a little more than 4 Mbit / s, the speed of the connection is established automatically. The resulting peak capacity was greater than 5 Mbit / s.

Test 2

Lets see what happened when you connect to 2 Mbit / s. The results are shown below in two charts:

As expected, the difference in the results of testing throughput with WEP and without him slightly, by less than 1%. But in testing the PCI versions, as well as when they are testing with a throughput of 11 Mbit / s, with WEP enabled throughput decreased. When testing PCMCIA cards it turned out the opposite – the capacity not only declined, but was higher, although it can also be considered the exception rather than the rule.

Whats in this test was pleased – the results of rate can be seen that when you turn on encryption performance is sufficient. This can be seen in the last two rows of the table: when testing the laptop with WEP, the average throughput was higher than the test without it.

As before, in all tests were seen falling capacity, wore a short-term in nature.

Testing bandwidth

For this test, we ran the script “throughput”, is also changing the amount of data for each transfer of 100 000 200 000 bytes, as in the previous test, and with different number of repetitions. Thus, the time of each test ranged from three to ten minutes.

The average capacity of about 1350 turned kbit / s. The resulting peak bandwidth was 1519 Kbit / s, the lowest – 769 kbit / s.

Result

The effective capacity of short reaches values ??higher than 5 Mbit / s. The average installed in the 4 Mbit / s. For the 802.11b standard are acceptable values. In the second test, the magnitude of the average throughput in 1350 kbit / s, the maximum was about 1.5 Mbit / s.

Another of the benefits it should be noted that the performance of almost falling when you turn on WEP, then you do not have any barriers to its use and, thereby, provide greater network security.

Findings

In general, good cards, but there are a number of weaknesses that we have grieved. We did not like the results of the equipment at a distance, even smaller than stated in the documentation. You can not achieve maximum zavyalennogo distance of 450 meters, the device drops the connection much earlier. And in the building, about 30-40 meters from the access point, the computer tried in vain to find a network, even when you try to connect manually to 1 or 2 Mbit / s. The manufacturer also claims that at this distance communications should be set at a speed of 11 Mbit / s. With the more expensive adapters of other companies, we have not seen similar problems.

We can only guess what caused this behavior: low power devices or firmware malfunction. We hope that the second answer is correct, and with the release of new firmware problems resolved. I would like to see in the SMC devices the ability to configure the transmitter power. Adapters of other firms tend to have such an option.

Another problem – even with a slight distance from each other, working in Mode 2 or 5 Mbit / s, moving to 11 Mbit / s, but this can be attributed to the above – a distance of less than the stated amount. All these troubles have occurred in either Ad Hoc, and in the mode Inrastructure.

Is it worth buying?

Even in the ideal case, one should not expect the bandwidth is higher than that of wired 10BaseT or 10Base2. However, none of the wireless adapter, passed through our lab, claimed 11 megabits per test is not stretched. As to the pros, then a relatively low price, you get freedom of movement, the relative ease of installation and lack of wires – previously inalienable attributes of computer networks.

When it is necessary to reflect the acquisition of such equipment? When you create a temporary network, if you can not the cable, if necessary, create the possibility of free movement for some areas. In other cases, considerably more than the budget decision will be buying a wired adapter.

Thank you for providing the equipment company SMC Networks.