30

The 2.4GHz band is one of many portions of radio spectrum, called the Industrial, Scientific and Medical (ISM) bands that are allocated for unlicensed use. As long as you operate within the power and antenna limits, you can pretty much do what you want. So the short answer is, you can. But there are very good reasons why you shouldn’t. Part of the ...


20

Avoidance is used for the very simple fact that every radio ("client") is not necessarily in range of each other. Thus, without the AP coordinating who can talk, distant radios may step on each other because they cannot know the other is transmitting.


20

IEEE 802.11 is a standard that describes procedures, limits, values, algorithms to enstablish a WLAN connection. Wi-Fi is a brand name owned by the Wi-Fi Alliance that certifies with pre-defined tests the interoperability between all device with this mark. WiFi devices are based on IEEE 802.11. Not every device that uses IEEE 802.11 is Wi-Fi cerified.


19

In a wired CSMA/CD Ethernet environment, it is possible to detect a collision because there are separate TX and RX pairs (using the example of 10BaseT). If a half-duplex 10BaseT NIC sends a frame on the TX pair, but sees that frame is corrupted on the RX pair, the NIC detected a collision. However, with an 802.11 wireless device, there are no "conductors," ...


18

Wi-Fi is IEEE 802.11, the same way that ethernet is IEEE 802.3, token ring is IEEE 802.5, FDDI is IEEE 802.8, etc. These are some of the IEEE LAN protocols, and the IEEE working groups associated with the protocols. See this answer for more IEEE 802 working groups.


17

Robert Wilson, a graduate student at USC, prepared an analysis of 2.4GHz and 5GHz propagation through common materials, with a useful Table 3. It looks like Plexiglas incurs about a .36dB loss at 2.3GHz and about a .93dB loss at 5.25GHz, in addition to the slowdown caused by the slower speed inside the material. You probably wouldn't notice any decline in ...


15

In Short,Wi-Fi is more of a technology name and 802.11 is the IEEE standard. There are different variants of 802.11 based on your bandwidth ,Modulation schemes etc. I would always use the specific standard in documents and datasheets instead of just mentioning Wi-Fi.This will help to give a clear cut information to the reader and engineers as well. The ...


14

In a WLAN iperf TCP throughput test, multiple parallel streams will give me higher throughput than 1 stream. I tried increasing the TCP window size, but I still cannot achieve the max throughput with just 1 stream. Is there something else in the TCP layer that is preventing the full link capacity from being used? In my experience, if you see significantly ...


14

The distinction to understand is that while an 802.11 device is transmitting to a receiving device, either one (or both) of these devices may not be the actual source or destination of the L2 traffic. So this can create situations where you need four different distinct addresses: Transmitter Address (TA) Receiver Address (RA) Source Address (SA) Destination ...


12

The short answer is yes, it is not only possible, but happens all the time. Examples of this are CTS-to-self, beacons (sent by APs), probe requests, probe responses and a number of other management types of frames. However, it seems that isn't exactly what you mean and are looking for a way to transmit data from one device to another without any sort of ...


12

As I understand Wifi, it can never true multicast, as each device holds a '1:1" relationship with the AP, and then receives the same packet... then the next device connects and gets the same packet. Your understanding is flawed. Multicast does exist, but like most management traffic on a wireless network it must run at the lowest supported base/basic/...


11

You are correct, they leave the IP information so that you don't accidentally lose connectivity when working on an AP remotely. As you noted, the button (which requires you to be local) will default the configuration including the IP. You can also do this by entering the following command: write default-config


11

My personal recommendation is to never use extenders/repeaters if you can avoid it. Repeaters do just what they say and repeat a signal they hear. This reduces the overall performance of wireless, as wireless is a shared medium which means only one device can be "talking" in the same area at the same time. Each frame (in both directions) is now ...


11

Keep in mind that a higher frequency doesn't translate to moving data faster, rather it is the modulation of the signal that determines that data rate. The 802.11n standard either requires or makes optional the same set of major features and modulations in both frequency ranges. However, that being said, there are a number of best or common practices that ...


11

This entirely depends on the chipset in your device, as not all of them have equal capabilities on Tx/Rx rates. I personally have found no better resources than wikidevi.com for looking up the capabilities of wireless network adapters. To understand wireless that is 802.11n or newer, you need to understand the shorthand often used in their technical ...


11

In this scenario, your phone has at least two network interfaces: WLAN and 3G. Each interface has his own IP address and mask. They usually install as two routes on the phones routing table, the locally connected network and a default gateway. Let's see a simplified example: Interface: Wifi IP/mask: 192.168.10.10 255.255.255.0 Default gateway: 192.168.10....


11

There are two types of wireless extenders. First would be an extender that uses some sort of mesh technology. This type of extender is typically only found within an enterprise deployment and will establish a connection to the network in addition to also acting as an AP. Often a mesh device will use two radios, one providing the "back haul" and one to ...


11

Hire a professional who has warehouse experience. If you were using an enterprise vendor, I would suggest looking at their consulting services as they have probably done this with their products a number of times. Warehouses and stadiums are considered the two most difficult wireless environments to work in with 802.11. There are many factors that make ...


11

Lets test this out then. If we send multicast packets to multiple devices connected to a WiFi access point at a constant rate, then the access point should report the same amount of traffic. To run this test, I'm sending packets from a wired PC to an an android tablet and a raspberry pi. Don't have any iOS devices. The network testing tool iperf can easily ...


11

Why then does the client need to encrypt the broadcast using the GTK? It doesn't. Since the AP broadcasts, not the client, the client doesn't use the GTK to encrypt the frame. The AP does. Why can't the client just encrypt the broadcast frame using its PTK, and the AP decrypt it, ... Exactly. This is what happens. ... the AP decrypt it, then encrypt ...


10

There could be many causes for this, but your suspicion about the AP not being built to broadcast multiple WLANs is not one of them. I would start by looking at this list: What version of code are you running on the AP? Upgrade to a more recent code if possible, as there may be bugs in your current code. Check for sources of interference or other usage on ...


10

it sends %CDP_PD-2-POWER_LOW: All radios disabled to the console... Question: How can I make this AP turn on the radios? I talked with a Cisco Wireless Consulting SE... The first problem is that the recovery image (i.e. rcv-w8 image) does not have the firmware for Dot11 radios... so I had to upload new firmware. I normally use archive download-sw /force-...


10

To understand the answer to this question, you need to understand some wireless terminology. The service set identifier or SSID is the logical (i.e. human readable) name used by a wireless network. The basic service set or BSS consists of a single access point (or virtual access point) and any stations associated to the AP (VAP). Each WLAN that an AP ...


10

The easy way to do it could be: On your WLC home page you should have something like: You can reset the stat through the gear icon on the top right corner, selecting "Clear Dashboard Data" Then the machine should quickly appear in the "Top Client Devices" list, you can click on it and you will get the IP address and the mac address of the device. Bonus ...


9

There are two main options for controller redundancy in Cisco's current wireless offerings. You can either use Backup Controllers or High Availability; depending on the firmware level of your 5508's, your acceptable failover time, and your budget. Based on your question, we're working with the following topology: Traditionally, utilizing Backup ...


9

In Infrastructure/ESS mode, it doesn't make much sense to capture packets going to other stations in promiscuous mode, for several reasons : The 802.11 ESS operation assumes that, in a BSS, all non-AP stations must send all their packets to the AP, regardless of the destination address. This is implemented as follows: if a station wants to communicate with ...


9

802.11 are the IEEE specifications that implement wireless local area networks. In common parlance I think 802.11 is more or less synonomous with Wi-Fi. Note that Wi-Fi is actually a trademarked term of the Wi-Fi Alliance.


8

Use a script to login to the WLC and run the transfer command: http://www.cisco.com/en/US/docs/wireless/controller/6.0/command/reference/cli60.html#wp1327209 You can use this to upload the config from the WLC to another server via TFTP/SFTP/FTP. (Cisco Controller) >transfer upload mode sftp (Cisco Controller) >transfer upload username my-osx-user (...


8

802.11 b/g cards can only sniff 802.11b/g traffic. They cannot see 802.11n traffic. See caveats A & B, below. Caveat A: Many 802.11n APs are configured to allow b/g connections. Once you have an IP connection, all kinds of things are possible, including ARP cache poisoning, mac-floods, MITM attacks, etc... EDIT for queston in the comments: Caveat B:...


8

This is how you would set up dual-band 2.4Ghz / 5Ghz on a Cisco autonomous AP for Open auth... Basically just associate the SSID with Dot11Radio0 and Dot11Radio1; Substitute these WPA PSK configs if you want WPA PSK. I can add PEAP or other EAP methods after I get home, but I haven't got access to my EAP notes right now. ! version 15.2 no service pad ...


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