Questions tagged [ieee-802.11]

For questions about the IEEE 802.11 series of protocols, also known as Wi-Fi. This tag should be used when asking about enterprise or corporate Wi-Fi networking questions. Questions about home wireless networks are off topic.

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10
votes
2answers
14k views

How do wifi clients detect SSIDs from APs?

How can my wifi board detect wireless networks that are in range? What protocol is used to communicate with the devices in the area to announce a wifi AP? Does every router transmit on its own ...
11
votes
1answer
11k 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 ...
18
votes
4answers
24k views

Cisco APs ignore DHCP Option 43 and use CAPWAP UDP broadcasts

Background I am trying to redeploy Cisco 1242 LWAPs on new Cat4507R+E switches, which means the IP address of the WLC is changing for that LWAP. For some reason, I have to configure ip helper-...
2
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2answers
497 views

What is 802.11 in the IEEE 802.11?

What is the number 802.11 in IEEE 802.11 representing? I mean, if you break it down, what exactly are 802 and 11?
13
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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 ...
7
votes
1answer
764 views

Why do we have authentication before association in 802.11

Why does client authenticate before associating with the AP. What does open system authentication even achieve. I fail get an accurate reason from my web searches. Best reason I do get is unlike wired ...
5
votes
2answers
2k views

Why is RTS/CTS optional for IEEE 802.11?

In wikipedia it is stated: Request to Send (RTS) frame: The RTS and CTS frames provide an optional collision reduction scheme for access points with hidden stations. A station sends a RTS frame as ...
9
votes
2answers
27k 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 ...
13
votes
3answers
33k 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 ...
10
votes
3answers
4k views

Why is my UDP broadcast wireless communication capped at 1 MB/s?

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 ...
5
votes
2answers
2k views

Is 802.11 bitrate symmetric?

I was wondering when a device spec says that it supports WiFi bitrate of 300 Mbps, is this rate symmetric, i.e. is it the same rate in transmit (device to access point) and in receive (access point to ...
2
votes
1answer
64 views

Multiple routers with one long range antenna

Wifi routers have a limit on the number of clients that can connect, Assuming i have many routers and i connect them together via wireless bridge, then i connect one single long-range antenna that ...
2
votes
1answer
3k views

Relation between Ethernet and 802.11 headers

I would like to ask about the relation between 802.11 and Ethernet L2 Link layer. Are they dependent of each other? Or can they be seen as independent L2 link layers (with only similarities in ...
7
votes
2answers
593 views

How is the Groupwise Transient Key used in WiFi networks?

In Wifi WPA, I understand that during association, a 802.11 client and AP negotiate a Pairwise Transient Key (PTK), using which the Groupwise Transient Key(GTK) is provided to the station. I ...
7
votes
2answers
130 views

How the packet is routed between two host from same sub-net and associated with same AP?

Given host 'A' and 'B' have IP 10.10.0.5 and 10.10.0.8 respectively, the sub-net mask for both are 255.255.255.0, both 'A' and 'B' are associated and connected to the same AP, and the AP is connected ...
3
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2answers
1k views

Does WiFi broadcast traffic from a station go through the access point?

Let's say I've got two devices connected to my Access Point, a laptop and a tablet. If the laptop sends unicast traffic to the tablet, I understand that it must go through the AP. However, how is ...
3
votes
1answer
543 views

What does MTU depend on?

I'm trying to understand what factors determine the MTU. For instance, why 802.11 has MTU of 2304 while Ethernet MTU of 1500? Are there restrictions of the physical medium or arbitrary design ...
2
votes
2answers
729 views

Is it really necessary for APs to constantly send beacon frames (always be in “discovery mode”)?

Why do wireless APs constantly transmit (e.g., with a beacon interval of 10×/sec.), even when no devices are connected to them? Doesn't that just cause needless RFI? Is it really necessary to ...
1
vote
2answers
108 views

Airtime efficiency

How is airtime efficiency measured? How does one increase it, decrease power consumption, and minimize the amount of RF transmitted? cf. these comments