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75 lines
3.6 KiB
Markdown
75 lines
3.6 KiB
Markdown
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# DAWN
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DAWN is a decentralized controller for wi-fi clients (eg, laptops, phones)
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that aims to ensure that each client is connected to an access point (AP,
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aka "wifi router") that will give good network throughput. This reduces
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wastage of radio capacity due to weak / distant radio connections that
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cause transmission retry, degradation of speed, etc.
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Decentralized means that DAWN is a peer-peer network of instances - there
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is no controlling "master" node. Every instance of DAWN will find its
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peers via uMDNS (aka Bonjour) network discovery. Further DAWN instances
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can therefore be added without explicit configuration of the whole
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network, reducing network maintenance overhead.
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## Installation and Configuration
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Installing DAWN is quite simple. The TL;DR version for anyone not wanting
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to read the [installation guide](INSTALL.md) is:
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- Install DAWN on each AP that you want to be a part of the optimization
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network
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- **Be sure to install a full wpad-\* version and not wpad-basic**
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- Be sure to configure extender routers as "dumb AP"
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Top tip from the [configuration guide](CONFIGURE.md):
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- Be sure to enable the DAWN functions that you want (at least "kicking")
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## How DAWN Works
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Each DAWN instance gathers information about two types of client: those
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that are currently connected to the host AP, plus those querying whether
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to connect. It then shares that information with other DAWN instances.
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Each then has a view of how well any AP can "see" each client device, and
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that then allows DAWN to steer a client to a different AP when appropriate.
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For example, if a device is currently connected to AP1 with a signal
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strength of -65dB it may be quite happy to stay there because many devices
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will not look to roam until the signal goes past -70dB (note the minus
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sign: -70dB is more negative / worse than -65dB). However, if DAWN on AP1
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knows that the same device can see AP2 at a level of -55dB then DAWN can
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tell the device to switch to AP2, which will improve overall radio
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performance if applied to multiple devices across multiple AP.
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DAWN can also evaluate other parameters that a device may not include in
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its roaming decisions, such as currently connected clients per AP,
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availability of speed enhancing capabilities, etc. However, it is
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ultimately for a client device to decide which AP it will connect to so it
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may ignore DAWN's proposal, especially if it is using a significantly
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different algorithm to DAWN.
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DAWN works best with networks where AP and devices have 802.11k
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capabilities for discovering the quality of radio signals, plus 802.11v
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for requesting devices to move to a different AP. If 802.11r is enabled
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for fast, seamless transfer of a device across APs then it enhances the
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overall user experience, but DAWN doesn't directly use it.
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802.11k/r/v were developed to enable the type of functionality that DAWN
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provides, so older devices that do not have these capabilities are by
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definition harder to control. DAWN will try to steer "legacy" devices if
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configured to do so, but it can be a less than perfect user experience due
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to the time taken to create connections to the new AP.
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## LuCI App
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There is a luci app called
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[luci-app-dawn](https://github.com/openwrt/luci/tree/master/applications/luci-app-dawn)
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that adds some DAWN information to the management interface of an OpenWrt device.
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NB: As of early-2022 it hasn't had the developer attention it needs
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recently, so may not be working as well as you might like.
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## Developers
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If you want to use versions of DAWN that are not fully packaged yet or to
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work on a fork of the code yourself then see the [Developer
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Guide](DEVELOPER.md).
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