Questions tagged [wireless]

For questions about wireless networking (802.11), including any licensed or unlicensed RF medium used to provide point-to-point or point-to-multipoint network links.

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39
votes
11answers
36k views

How do you prevent rogue wireless access points on a network?

Depending on what type of traffic is going over the network, it's often not feasible that an employee brings a wireless router and sets it up into your network. This is because often, they are not or ...
22
votes
5answers
85k views

Is it safe to use any wifi channel in the 2.4GHz band?

It seems that everything I read about wifi says there are only three usable channels in the 2.4 GHz band; however, there are eleven 2.4Ghz wifi channels allowed in the US. If everyone is using 1, 6 ...
22
votes
1answer
2k views

All WiFi clients losing connectivity at the same time

In order to provide WiFi coverage for a small office area, a Cisco autonomous single-band 1041 (AIR-AP1041N-E-K9) is used, running software version 12.4.25d-JA1. The access point is having a basic ...
21
votes
7answers
7k views

Building new network and need 200+ wireless devices

I'm planning the network for my company's new office space. I'm not an expert so I'd like to present my plan and ask y'all nice folk to tell me if and where I'm making mistakes. Assumptions: Office ...
20
votes
2answers
6k views

Can a probe request be answered on a different channel?

I am monitoring the 802.11 traffic in my network, and especially the active probing from my smartphone. I am sending Probe Requests for certain hidden SSIDs, but also an Undirected Probe Request, ...
19
votes
4answers
24k views

LAP ignores DHCP Option 43 and uses CAPWAP UDP broadcasts

Background I am trying to redeploy Cisco 1242 LAPs on new Cat4507R+E switches, which means the IP address of the WLC is changing for that LAP. For some reason, I have to configure ip helper-addresses ...
18
votes
4answers
23k views

Why does WLAN use Collision Avoidance and not Collison detection?

I am searching for this answer for quite some time now. Why there is CSMA/CD in LAN but CSMA/CA in WLAN? The best explanation I could find is "due to extreme ratio in transmitting and receiving power,...
17
votes
2answers
57k views

How does a WiFi range extender work?

I have a WiFi base station, and a WiFi range extender. Both of them have the same SSID. When a device connects to that SSID, what exactly happens? How does the device know that base station and range ...
15
votes
2answers
777 views

Wireless Probe Request Forwarding Best Practices?

I'm working with a couple Cisco WLCs and I know that they use information about client signal strength in determining device locations but I was reading up on "probe requests" and found that, by ...
14
votes
7answers
14k views

Full-duplex with two antennas

It is said that wireless is a half-duplex medium. "Dual-band" stations are now common, with one antenna in the 2.4 GHz band, and the other in the 5GHz band. Suppose now we have stations with both ...
14
votes
4answers
1k views

Is a wireless only network (for end users) a viable option?

We are constructing a new building, and our CIO is pushing for a solution where he doesn't have to spend the money on copper runs to all the user stations and wants to use wireless only for this ...
13
votes
5answers
7k views

Do WiFi and IEEE 802.11 mean the same thing?

I would like to know if WiFi can be generally referred to IEEE 802.11 standard in the context of IoT/machine-to-machine communications or the latter can be referred to as a more general family. I have ...
13
votes
3answers
32k views

Mac-flap due to roaming clients on wireless

We are running an Aerohove wireless network (controller-less).. I occasionally get mac-flaps within the VLAN tied to a SSID. I know this is coming from a roaming client.. The problem is that the ...
13
votes
3answers
5k views

Identifying a Cisco access point post-install

We have about 50 Cisco 1242 access-points and we're managing them with a Cisco 4404 Wireless Lan controller. The guy who installed the APs did not assign a location to the access points in the ...
13
votes
2answers
8k views

Broadcasting wifi packets without a network

I have a question about Wifi, I couldn't find the answer anywhere. Is it possible to send a packet over wifi without having joined any kind of network (ad-hoc or not)? I would like to be able to ...
12
votes
3answers
23k views

Wifi TCP iperf throughput: 1 stream vs multiple streams?

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 ...
12
votes
1answer
20k views

WLC - How to disable 2.4Ghz

Is there any way I can disable the 2.4Ghz and just leave 5.0Ghz channel enabled on a per WLAN (SSID) basis? Or the only way is to disable the AP's radio and leave 5Ghz enabled?
11
votes
3answers
24k views

What would cause really sporadic packet loss, when signal strength is fine

I have a router connected to a modem. My intention is to connect to this router from an office that's about 200 feet away and through 2 walls. The router signal is not strong enough to get to the ...
11
votes
4answers
11k views

Is there an automatable way to backup the configuration from a WLC 2504 controller?

I am looking for a way to backup the controller configuration file via an automatic process. I've seen links to the web interface which appears to do a one-time tftp copy of the config to a remote ...
10
votes
3answers
4k views

Why does my UDP Broadcast wireless communication is capped at 1MBs?

I am trying to implement Network Coding over a meshed network. Therefore I need to send packets to several destinations, this is way I am using Broadcast packets. But I can not understand why this is ...
10
votes
1answer
2k views

Plexiglass and 2.4GHz wifi signal

I have very simple question: If device which uses regular WiFi (2.4 GHz) connection (i.e. USB receiver for wireless mouse or mobile phone) is put into plexiglass case, would that lower connection ...
10
votes
4answers
2k views

Raw-Ethernet Frames

Recently I was puzzled by the following articles about Raw-Ethernet frames: RAW ethernet vs. UDP Message Passing Using Raw Ethernet Frames Briefly, both of them discusses that it is possible to ...
10
votes
2answers
3k views

omnidirectional antennas and the dipole antenna

This article on Cisco's website is the clearest explantion of omnidirectional antennas I've found. What isn't so clear to me is... 1) Why is the dipole antenna the most common design for ...
10
votes
1answer
10k views

Four layer-2 addresses in 802.11 frame header

I am new to wireless LAN. I see that it has 4 addresses in the frame header. In case of a Wired Ethernet, there are only 2 mac addresses, the source and the destination (which is essentially the ...
10
votes
4answers
31k views

converting AP from CAPWAP to autonomous - BVI1 interface gets reverted back to DHCP

Has anyone ever gotten this message in the middle of converting a CAPWAP access point from CAPWAP to autonomous? *Mar 1 00:47:59.399: %CAPWAP-3-STATIC_TO_DHCP_IP: Could not discover WLC using static ...
10
votes
1answer
3k views

High-Density WiFi & 2.4GHz Co-channel Interference design

The issue: CCI (Co-channel Interference) on 2.4GHz. The Environment: 40 seats per classroom. Higher-ed, so extremely mixed client base. AP-on-a-stick set to 24Mb lowest Mandatory data rate & ...
10
votes
1answer
3k views

Cisco WLC External WebAuth Apparent Random Behavior

On Cisco 5508 v7.2.103.0, I have a couple of WLANs configured. Call them ABC and XYZ for the sake of this question. ABC uses 802.1X and gets a splash page redirect URL pushed down. XYZ uses PSK and ...
10
votes
1answer
2k views

Using RADIUS to restrict SSID on Cisco Aironet

I would like to use my RADIUS server to restrict access to configured SSID on a per user basis. According to the documentation linked above i add the following attribute to a test user: ospite-5vh ...
9
votes
2answers
24k views

Can I truly multicast over WIFI?

Am streaming UDP over wifi (5ghz) - approx 1.5k/packet... trying to stream to ~10 devices simultaneously, with extremely low latency.. As I understand Wifi, it can never true multicast, as each ...
9
votes
2answers
3k views

AP3602 with rcvk9w8 image throws “%CDP_PD-2-POWER_LOW: All radios disabled”

We recently bought some new AP3602Es from Cisco. I'm trying to understand why this AP will not turn on the radio when we are sending enough power to the AP. I'm using inline power from the switch, ...
9
votes
2answers
11k views

what to know about DSSS vs OFDM

In all the detail on DSSS and OFDM, I have missed which characterics of DSSS and OFDM make these distinct technologies. Nothing I've read appears to contrast the two. As I understand it, both DSSS ...
9
votes
1answer
737 views

Why does a Cisco AP keep its static IP when erasing NVRAM?

When I erase the nvram on a Cisco AP (1252 and 1262), the static IP assigned to interface BVI1 is not erased. When I do a show startup-config it says there is no startup config. But it always boots ...
9
votes
4answers
5k views

CISCO Wireless Lan Controller and AP's design question

There are a couple of questions on design solution. CAPWAP tunnel is created between the controller and the access points. The ends of the tunnel are the controller's "ap-management" interface and ...
9
votes
2answers
3k views

Cisco AP not powering up until pressing mode button

We have two Cisco 2602E APs and one Cisco 3602E AP deployed at a location in China. They are connected to an HP ProCurve 2910al PoE switch. The 3602E powers up fine when the switch is rebooted (i.e. ...
9
votes
1answer
472 views

NCS Cisco Prime licenses

I am almost 100% sure this is not possible, but just thought about double checking with someone with more expertise on wireless. Suppose I have the following scenario: WLC-1 with 25 licenses on ...
9
votes
3answers
1k views

VM on a client connected to a Cisco 1262 unable to DHCP (but IPv6 works fine)

I recently replaced wireless at a site from the internal AP on an 877-WM with a (standalone) 1262 running 15.2(2)JB. I've configured the AP pretty much the same as I always do for Cisco AP's for ...
8
votes
3answers
307 views

Is there a way to recognize the location where a client connects to the network?

So yes, I'm pretty new to networking and I hope this isn't a stupid question. I couldn't find an answer on google nor could I find something here (but I'm also sure about the terminology), so I ...
8
votes
3answers
20k views

Wifi dropping randomly on Cisco AP-1602

I have a single Cisco AP-1602 broadcasting 3 SSIDs in a small office. Some of my team are complaining about random drops in network connectivity. (Over 3 days, I've had 3 different users complain ...
8
votes
2answers
2k views

Does a wireless access point has a role between two wireless devices?

When I send packets to another computer (both computers have wi-fi) is the AP required to communicate or can the other machine receive the information directly from my computer without the AP?
8
votes
2answers
3k views

Which address should I choose to send a multicast message on an wireles ad-hoc meshed network?

I am trying to implement a wireless multicast ad-hoc network, but I don't know how it works. I think I have to send my packets to a specific 224.0.0.* address, but I don't which one choose. My ...
8
votes
2answers
1k views

intersymbol interference (ISI), channels, and frequencies

When describing 802.11b/g and the 2.4 GHz channels, or 802.11a/n with 5 GHz channels, textbooks (CWNA Official Study Guide) often show some figure with channels spaced such that certain channels ...
8
votes
4answers
229 views

What is the name of the feature of a Router that prompts a user with a webpage when connecting to network?

The context of this question is for a customer WiFi installation at retail locations. What I want to achieve is that when a user connects to the network for the first time, a webpage is opened on ...
8
votes
2answers
677 views

Is 802.11k a security risk?

I'm looking at enabling 802.11k on my Cisco WLC. I see that it is a per-WLAN feature and that leads me to wonder if there might be any reason to not enable it? Specifically, does anyone know if there ...
8
votes
2answers
2k views

Wireless Controller based vs Non-controller based

I am looking at upgrading our wireless infrastructure from 60+ SOHO access points to an Enterprise level solution. We are currently testing Ubiquity (have 12 in our most dense areas) and it seems to ...
8
votes
2answers
17k views

How are multiple SSID's handled on same access point?

In case of multiple SSID's on some AP, how is the information forwarded? I mean, the simplest AP's have just one wireless interface so its basically receiving trough one antenna and send it trough ...
8
votes
2answers
38k views

Cannot use 5GHz band Wi-Fi from channels 100-140

My AP operates in the 5Ghz band. There are no problems using Channel 36 to 64; however, clients can't even detect the SSID if I use Channel 100 to 140. Below is a screenshot of Netspot showing all ...
8
votes
1answer
2k views

Staging Many Lightweight Cisco AP's for Deployment

My organization is soon going to be deploying approximately 600 new Cisco 2602i access points in a CAPWAP deployment with several 5508 controllers. This is an infrastructure refresh; currently we ...
8
votes
1answer
991 views

Which address should I use to receive a UDP wireless multicast with iperf?

On computer 1 (192.168.1.3): I made a route to be sure that my communication pass through my wireless card sudo route add -net 239.0.0.0 netmask 255.255.255.0 dev wlan2 I launch iperf with the ...
8
votes
2answers
22k views

Single Access Point vs. Multiple Access Points

Vague Question: If one access point can do the job adequately is there still an advantage to using more than one? Scenario: 1 access point at the center of your network required coverage area should ...
8
votes
3answers
4k views

Cisco WLC: Per user authentication, many Vlans, few SSIDs

We have a simple problem. We want to restrict our wireless users to certain business websites based on their username when they login. We have many kinds of wireless devices: voip phones, cell phone,...

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