hey all you all protected folks out there this is Jelan from Sophos
support and today we're talking all about Wi-Fi and preparing to deploy sophos
wireless access points. Whether you're deploying a new wireless network
or making changes to an existing network there's a lot of factors to consider
this can be a pretty complicated process so we've put together some info
to get you started on the right foot and avoid problems like slow or
inconsistent Wi-Fi connections. In this video we'll be going over the following
topics: Wireless frequency fundamentals, network requirements, site surveys and
heat maps, and some additional considerations directly from support.
Let's start by talking about frequencies wireless network scene function off to
different frequency bands 2.4 and 5 gigahertz. Now it's important to
understand the attributes of both frequencies as they'll both have pros
and cons in your environment. The 2.4 frequency band can penetrate objects
better than 5 gigahertz so can achieve a longer range in your environment. It's a
shared frequency band so APs aren't the only devices that use 2.4 gigahertz
other devices like cordless phones and microwaves and Bluetooth devices also
use 2.4 gigahertz so they can actually cause interference on a 2.4 network the
2.4 frequency band has 11 different channels that data can be transmitted on
but only 3 channels 1 6 and 11 are non-overlapping
this means 1 6 and 11 are the only channels we can use without running into
channel overlap issues we'll talk more about channels shortly our other
frequency band option is 5 GHz now 5 gigahertz is less susceptible to channel
interference but more susceptible to signal degradation 5 gigahertz is a
higher frequency so it's waveforms are much smaller and faster than 2.4
gigahertz it's more difficult for higher frequencies to penetrate objects but
they have a faster transmission rate meaning much faster potential speeds 5
gigahertz has 24 non-overlapping channels so a lot more to choose from
because of that as channels are less likely to get congested due to high
traffic or interfere with each other if multiple ApS are close together
now not all devices support 5 gigahertz so make sure you evaluate your client
device requirements and ap capabilities before selecting a band to use we'll
talk more about that in the network requirements section now let's talk
about channels the concept of channels can be a bit confusing but here at
support we see a lot of cases caused by misconfigured channel selection and
width so it's very important to understand basically each band can have
dedicated lanes that traffic can be transmitted on the more data being
transmitted on one Lane means the more likely congestion can occur so if your
network a neighboring Network for example are
both using channel 1 it's potentially double the traffic on channel 1 this can
cause major co-channel interference or CCI on both networks CCI is crosstalk
from two different radio transmitters or antennas on the same Channel when this
happens you can experience anything from just slow Wi-Fi - as far as completely
unusable Wi-Fi even though your device shows fully connected in this scenario
it's best to switch your AP to a different non overlapping channel like 6
or 11 and that should resolve the issue a channel is essentially a segment of
the frequency band that can be either 20 40 80 or 160 megahertz wide 2.4
gigahertz can actually only accommodate a maximum of 40 megahertz wide since the
entire range is only 72 megahertz wide itself the wider the channel the more
throughput capability has which means potentially faster Wi-Fi think about a
channel like a highway if you double the amount of lanes you can double the
amount of traffic this comes with a price however as the wider the channel
is the less channels you have and more so the less non-overlapping channels you
have this raises the likelihood of adjacent channel interference occurring
adjacent channel interference occurs when two or more channels overlap with
each other for example if you have 2 AP's both using 2.4 gigahertz one on
channel 1 and one on channel 2 since those two channels overlap the signals
will interfere with each other in this situation again you would want to choose
channel 1 for the first AP and channel 6 or 11 for the second ap because they
don't overlap essentially the same resolution as the first scenario in most
networks we tend to keep channels at 20 or 40 megahertz max width to increase
the amount of non-overlapping channels we have to work with but obviously that
means we're sacrificing potential throughput if you plan on using 5
gigahertz with 80 or 160 megahertz channels yes you can get great speeds
but make sure you're either not near other networks or you really plan your
channel selection well like many access points so close ApS can actually be
configured with automatic channel selections so the AP will detect the
channel with the least amount of traffic and switch to that channel this is
convenient in simple setups like home or small office with a few ApS but
sometimes high density environments deploying many ApS it may be best to
statically assign channels to ensure ApS aren't constantly switching between
channels next let's talk about the needs of your own network you need to identify
the following information to help you plan your wireless network
design applications that will be in use on your network number of simultaneous
clients types of clients areas to be covered and power availability different
applications have different throughput requirements for example voice over IP
has a minimum bandwidth requirement of 100 kilobits per second up and down but
3 megabits per second is recommended 1080p video streaming has a recommended
bandwidth requirement of 5 megabits per second and 4k streaming has a
recommended 8 to 20 megabits per second now these all don't sound like a lot but if
you have 50 users on skype calls at the same time you need at least 150 megabits
per second network to meet the recommended throughput requirement so
take note of the applications that will be in use on the network and make sure
you find out the throughput requirements you always want to make sure your
network can handle more than required because more bandwidth will result in a
lot less frustrated users than not enough most networks have more than one
users so knowing the amount of simultaneous users on your network is
extremely important Wi-Fi is a turn by turn system meaning every device takes
turns transmitting and receiving data not all at the same time an AP can
either receive or transmit data at any given moment
so 50 users on your network means 50 turns being taken sending and receiving
data even though it seems seamless when deployed well next you want to know the
type of client devices as well different devices use different wireless
technologies house under the 802 11 protocol suite take a look at this chart
here each standard of the protocol supports different bands and speeds as
we can see the fastest being 802 11 AC which only supports 5 gigahertz many
modern devices will use 802.11 n which support both 2.4 and 5 GHz
and is backwards compatible this is not all devices however so it's
important to know what devices are going to be on your network 802 11 a B and G
are older wireless technologies so they have slower transmission speeds if you
have legacy devices on your network this can actually sometimes slow down your
network speeds dramatically since each device takes turns transmitting and
receiving data the N and AC devices may be speeding along but they may get
slowed down waiting behind the B devices for example when deploying you can use a
setting called band steering to direct 5 gigahertz clients to use 5 gigahertz and
2.4 gigahertz clients to use 2.4 gigahertz this is basically like
creating a fast lane on highway so faster clients don't get slowed down the
newer Sophos apx series access points support all the 802.11
standards we just spoke about however the older AP series very per
model so make sure you know what standards your access points support
wireless devices can use multiple antennas to transmit more data through a
process called MIMO multiple in multiple out a laptop for example can have up to
three antennas whereas a smart phone usually only has one or two to conserve
battery power take a look at this chart looking at 802 11 AC we can see that
with one spatial stream or one antenna on a 20 megahertz channel the max
bandwidth is only 87 megabits per second but three streams its 289 megabits per
second so if your wireless devices only have one antenna even if you're using
802 11 AC your maximum throughput for that device can still only be 433
megabits per second if using an 80 megahertz channel if you're deploying
many access points chances are you can't use 80 megahertz channels as you would
limit the amount of non-overlapping channels available so you're more likely
using 20 or 40 megahertz meaning those devices have a maximum throughput of 87
or 200 megabits per second so no matter how fast your access point is your
network is really only as fast as the clients that use it the next thing you
definitely want to know is the areas that need coverage make sure you know
areas that need heavy coverage for example if the majority of users are
connected in one section of the office the APs in that area would then have
significantly more simultaneous clients connected to them this could mean you
need more ApS in that area to distribute the traffic which will require more
planning Sophos APs have been tested with 60 devices connected at once all
transmitting data with little degradation but every network will vary
depending on the applications in use and the environment it's generally a good
rule to limit the simultaneous clients for each ap to around 30 another thing
to keep in mind is that different building materials can affect wireless
signals significantly drywall and insulation will block far less signal
than thick concrete however in some parts of the world there may be metallic
coating between the drywall and the insulation that actually blocks wireless
signals significantly if your site has wood or metal covered walls depending on
the thickness this could also seriously impede the signal so keep that in mind
while planning and be sure to find out what building materials are used if
you're experiencing issues in terms of power availability so we'll see
these can be powered through Power over Ethernet or DC power some AP models can
be powered through both while some only POE so be sure to know what your APs
require make sure you know what infrastructure your site has available
for POE and keep in mind that APs can require more power on boot than
advertised so be sure your PSE can supply more than the minimum
requirements if an access point doesn't receive enough power it can actually
start rebooting randomly now the best way to plan your wireless deployment
specific to your site is to perform a site survey there are three different
types of site surveys passive active and predictive passive surveys are listening
surveys they don't actually send out any traffic to the network just monitor
radio frequencies in the area this can detect other APs in the area there's
signal strength the channels in use signal-to-noise ratio in the area and
other useful information this is the most common type of survey because it's
simple and you don't actually need to have any APs installed there's tons of
different applications to perform passive surveys you can even download
free apps for your smart phones however smartphones aren't designed specifically
to do this so may not give you the most accurate response active site surveys
are a lot more in-depth for an active site survey you send and receive data on
the network to get exact measurements these are done to deploy and
troubleshoot wireless networks as you measure things like throughput rates
packet loss as well as all the information from passive site surveys
when actively surveying a site you typically create a wireless heat map as
well to get a visual on the radio frequency strengths heat maps are
great because you can really see where your problem areas are predictive site
surveys are simulated site surveys for example in Sophos central Wi-Fi you can
upload an image of a to-scale floor diagram and place simulated access
points to predict placement since you input an exact distance scale this can
show a good representation of access point range on your site you can use
many tools to do this but remember a simulation can really only show range it
can't really account for building materials and interference sometimes all
three types of surveys are useful and there's tons of tools you can find
online to perform site surveys now let's talk about some additional
considerations directly from Sophos support engineers if you find there is a
section of your site where devices AP hop either increasing transmit power for
one ap or decreasing transmit power for the other AP may be an acceptable
solution if your APs don't connect directly to
the Gateway and go via a layer 3 switch create a static route for the magic IP 1
2 3 4 and route to the Gateway if using Sophos central Wi-Fi allow
access to the FQDN wifi.central. sophos.com there should not be any web
filtering or HTTP inspection applied to the traffic destined to or originating
from the AP as this causes problems for registration with Sophos cloud Wi-Fi
more SSIDs means more overhead be careful adding too many SSIDs as this
creates more management frames for your ap to handle which could impact
performance each ap can handle a maximum of 8 SS IDs and that includes the mesh
SSID of meshes in use if you choose to use the most compatible encryption TKIP
+ AES remember that the throughput and performance is greatly reduced due to
TKIP's processing requirements we suggest to use AES only and use a separate AP
for older clients that will only work with TKIP so thanks for watching
everyone if you had any further questions feel free to check out the
documentation links in the video description or view and post questions
at community.sophos.com that's it for me today stay safe out there