design and deployment of wireless lans for mobile...

Design and Deployment of Wireless LANs for Mobile Applications

BRKEWN-2000

Jerome Henry, Technical Marketing Engineer

© 2015 Cisco and/or its affiliates. All rights reserved.BRKEWN-2000 Cisco Public

Agenda• How Much Bandwidth do You Need?

• Determine Cell Size – Shape

• Determine Cell Size – AP Power

• Determine Cell Size – Protocols and Rates

• Determine Cell Size – 20, 40, 80 MHz?

• AP Placement Strategies

• Taking Care of the Roaming Path

• Client and AP 802.11 Optimizations

• Last Words - Troubleshooting

3

How Much Bandwidth do you Need?


How Much Bandwidth Is Required?

• It is most likely that you won’t be supporting just one application

• Design for the highest bandwidth demand that you intend to support

– What you need is the minimum acceptable throughput that the application will require

– Most users use only ONE high performance demanding application at a time

• Multiply this number by the number of devices that you need to support

• This is the aggregate bandwidth you will require in your space

• Often Less than You May Think

5

Application – By Use

Case

Throughput –

Nominal

Web - Casual 500 Kbps

Web - Instructional 1 Mbps

Audio - Casual 100 Kbps

Audio - instructional 1 Mbps

Video - Casual 1 Mbps

Video - Instructional 2-4 Mbps

Printing 1 Mbps

File Sharing - Casual 1 Mbps

File Sharing - Instructional 2-8 Mbps

Online Testing 2-4 Mbps

Device Backups 10-50 Mbps


How Much Bandwidth do You Need?

• Example, Skype (Up/Down):

• Now that you get the picture, a few other examples:– Fring (video): 135 kbps,

– Facetime (video, iPhone 4S): 400 Kbps, (audio) 32 kbps

– Viber (video) 120 kbps, (audio) 30 kbps

– Skype/Viber/other chat: around 850 to 1000 bytes (6.8 to 8 kb) per 500 character message

– Netflix (video), from 600 kbps (low quality) to 10 Mbps (3D HD), average 2.2 Mbps

– This bandwidth consumption is one way, you need to double for 2-way conversations

Call type Audio Video/screen share Video HD Group Video (5 people)

Typical

Bandwidth

30Kbps/30kbps 130kbps/130kbps 1.2 Mbps/1.2 Mbps 130 kbps/2 Mbps

6


Real Life Example?

• Density studies show 12 users / cell on average

– Expected 2 HD video calls (Skype type)

– 5 audio calls

– All users may browse

• Let’s do the math:

– 2 HD video calls = 1.2 Mbps x 2 x 2 ways = 4.8 Mbps

– 5 audio calls… mmm what application?• Skype too? 30 kbps x 5 x 2 ways = 600 kbps

– Others are browsing (5 people)… 250 kbps /people?

– Total = 6.65 Mbps needed

AP

Medical Center

I need 6.65 Mbps throughput everywhere in the cell- > therefore I need it here

Funny that browsing requires more than voiceShould I design for browsing?

7


VoIP Requirements

• VoIP carries voice sound with UDP and Real Time Protocol (RTP), voice control traffic uses Real Time Control Protocol (RTCP)

– Voice sound is converted to digital packets using codecs

– Resulting packet size ranges from 8 to 64 bytes per packet (+40 bytes L4/L3 headers, +L2 header)

• Voice has very strict requirements as an “application”

– Packet Error Rate (PER) <=1%

– As low jitter as possible, less than 100ms

– Retries should be < 20%

– End to end delay 150 – 200 ms, 30 ms in cell

– When these values are exceeded, MOS reduces

– Your mission is to keep MOS high

8


Video Applications

• Video uses video and audio codecs– Some codecs are built for real time exchange, some for streaming

– Video algorithms refresh entire images when large changes occur

– The changes generate traffic bursts

9

Cell Size and Shape


Cell Shape and Cell Size

Your cell shape depends on the antenna you use:

Directional

Omnidirectional


Cell Shape and Cell Size

Your cell shape depends on the antenna you use:

Directional

Omnidirectional

The cell size depends on 3 parameters:

The AP power level

The protocol you use (802.11a/b/g/n/ac)

The Data rates you allow

This is in open space… in real world, you also need to account for RF obstacles

Cell Size - AP Power


Power and Channel Plans

Many BYODs support all UNII bands

BUT: BYOD power varies with the band

Client devices cannot actively scan UNII-2e (ch 100 to 140)…

So those that support UNII-2e passively scan them only once every 6 to 18 cycles

(this means that, when on the Wi-Fi page, where an Iphone 5 scans every 11.4s, you

get UNII-2e channels every 68.4 s; when running to 8 second scans in roaming panic

mode, you get UNII-2e channels every 48 s)

Avoid UNII-2e in your channel planning if fast roaming is a concern

This may limit your options if you decide to use 40 MHz channels

15


Cell Size – Depends on Protocol and Rates

• Higher power does not always meanhigher SNR…

16

You are a bit quiet

Blah blah blah

Is it better now?

• Channel Utilization levels should be kept under 50%.

• You can check it using a spectrum analyzer like SpectrumExpert or Fluke AirCheck

• Noise levels should not exceed -92 dBm, which allows for a Signal to Noise Ratio (SNR) of 25 dB where a -67 dBm signal should be maintained.


Cell Size – Let’s get rid of the “Power” Checkbox

17

RF is symmetrical on paper:

“If your AP signal is heard by a client, the AP should hear the client signal symmetrically” (because the antenna Rx matches its Tx gain)

In real world, this is true, if the client RF parameters (Tx/Rx sensitivity, antennas, power level) are the same… otherwise, the client signal may be so weak that the AP can’t make sense out of it

2 causes:

Client rate decision is based on CLIENT perception of AP signal – if AP signal is strong, client will use high rate

The client reaches the AP mixed in surrounding noise – SNR too low and AP cannot demodulate

This is the AP signal (at phone level) This is the phone signal (at AP level)


Power -client Side vs AP Side

BYODs commonly have smaller power ranges than APs

18

Example: 3700i AP

(+4 dBi antenna on 2.4 GHz,

+6 dBi antenna on 5 GHz)Example: Iphone 5

Band Max Tx Power

2.4 GHz ISM 16 dBm

UNII-1 14 dBm

UNII-2 13.5 dBm

UNII-2e 12 dBm

UNII-3 13 dBm

ISM (Ch 165) 13 dBm

Source: FCC

This is the max Tx power This is the TX Power

(to the antenna)


Power, Spatial Streams and Data Rates

Do not think that multiple stream devices are always better

They may have higher power, but also require higher SNR

e.g.: 4 streams gives you a higher throughput

at same SNR level, than 2 streams

BUT the 2 stream device reaches its max speed

at 24 dB SNR,

while the 4 stream device needs 30+ dB

Conclusion: at same distance from the AP,

multiple stream devices will operate faster than

single stream device, but each individual stream

is slower


How can you tell the AP Power level?

WLC global level gives you the overall resulting power (this is what you care about):

(Cisco Controller) >show advanced 802.11a txpower

…/…

AP Name Channel TxPower Allowed Power Levels

-------------------------------- ---------- ------------- ------------------------

AP702W 157 *1/8 (20 dBm) [20/17/14/11/8/5/2/-1]

AP2602 48 1/4 (14 dBm) [14/11/8/5/5/5/5/5]

AP3702 (52,56) *2/5 (12 dBm) [15/12/9/6/3/3/3/3]

AP3602 (40,36) *2/7 (12 dBm) [14/12/10/8/5/-1/-4/-4]

AP is on 40 MHz channel

Power is dynamically assigned by WLC

Current level is 2 (12 dBm),

there are 7 levelsAllowed levels, 7 to 8 are the same,

so AP is configurable down to level 7


How can you tell the Client Power level?

You can check, live the client power levels on the AP (useful to check symmetry in AP to client and client to AP signal when building your cell edge):

AP7cad.74ff.36d2#debug dot11 dot11Radio 1 trace print rcv

*Jun 1 04:11:43.663: D5B70D90 r 6 49/46/42/48 54- 0803 000 m010B85 477AAF m010B85 33E0 477AA0 l46

*Jun 1 04:11:43.664: A2CEF918 r m15-2s 53/63/54/61 40- 8841 030 1A096F A36F20 m333300 76B0 q0 l100

This is on 5GHz radio, d0 is 2.4 GHz radio2 client signals reported

TimestampClient used MCS 15 (2SS)

Client RSSI on each antenna

Client SNR

Frame type (follows 802.11 spec)

Frame duration

Receiver and transmitter

addresses (last 3 bytes)

L+length of

rest of the frameWith WMM, shows the queue

without WMM, DCF queue index

Address 3

Sequence number


Some Client Max EIRPs

Model EIRP 2.4 GHz Worst* EIRP 5 GHz

Iphone 5 14.6 dBm 10 dBm

Ipad 4 15.2 dBm 22.67 dBm

Samsung S3 14.9 dBm 10.18 dBm



HTC One 14.4 dBm 13.8 dBm

Nokia Lumia 1520 13.1 dBm 11.6 dBm

ASUS PCE-AC66 22 dBm 22.83 dBm

* EIRP varies with sub-band, displaying worst of all sub-bands


So, what is the right Power?

In short: half your worst client max power

– E.g. you design for 5 GHz, worst client max is at 11 dBm, set your AP power to 8 dBm

Otherwise, you get this:

Which BYOD is the worst out there? No names, but 11 dBm is a good assumption


Power Levels and Client Density

– Reducing cell size by matching client

power and disabling low speed

decreases the user number per cell

– Each user has better throughput and

less risk of encountering interference

– Coverage holes might cause probing

devices to disturb the WLAN clients


What if I crank up my AP power a bit?

Bad design example: Client @ 12 dBm, AP @20 dBmBased on Rx AP signal, BYOD thinks 54 Mbps rate is okay

But client message is too weak,

and AP does not ACKRetry @ 54Againand AgainOkay try 36Wow, let’s drop to 12Now I get an ACKStart over…

Each message takes 8 times more to be transmitted

(including EIFS and retries)

Cell Size - Protocols and Rates


Cell Throughput by Protocol

• These are average throughputs, with one client close to the AP (high SNR/RSSI)

* Two spatial streams – note most PDA’s are SISO (MCS 7) 35 Mbps max

** You could have guessed that : 256-QAM max PHY is 1.3 Gbps, max throughput is typically less than half of max PHY

Protocol Throughput (Mbps)

802.11b 7.2

802.11b/g mix (1 b client) 9.5

802.11g 22.5

802.11a 22.5

802.11n (HT20 1ss MCS7) 35

802.11n (HT20 2ss MCS15) 75*

802.11n (HT20 3ss MCS23) 110

802.11ac (VHT80 3SS MCS 9) 630**


Cell Size and Data Rate

Each cell’s useful radius is determined by the minimum allowed data rate

1 Mbps DSSS2 Mbps DSSS5.5 Mbps DSSS6 Mbps OFDM9 Mbps OFDM11 Mbps DSSS12 Mbps OFDM18 Mbps OFDM24 Mbps OFDM36 Mbps OFDM48 Mbps OFDM54 Mbps OFDM


Protocol Support and Channel Utilization

Example low rate time waste ACK frames are sent at the first mandatory speed below the speed at which the

frame was received

802.11a/n: SIFS = 16 microsec

802.11b/g/n: SIFS = 10 microsec

802.11a/g/n: slot = 9 microsec

802.11b: slot = 20 microsec

1 DIFS = 1 SIFS + 2 slots

OFDM physical header = 16 microsec (312 b at 6 Mb/s)

802.11 physical header = 192 microsec (192 b at 1 Mb/s)

ACK sent at 24 Mb/s uses 4.67 microsec. airtime

ACK sent at 1 Mb/s uses 304 microsec. Airtime

Impact on throughput higher for shorter frames



36

5% After

60% Before

Before: 8 SSIDs, allrates allowed

After: 2 SSIDs, 802.11brates disabled



Disabling 802.11b in this network would:

Suppress 27% of frames (slow frames would be sent faster)

Decrease airtime consumption from 62% to 18 % if using 24 Mbps (slow frames take much longer to be sent than faster frames)

Reduce cell size:

Clients nearby would benefit from higher speeds

Clients far would not sick to the AP

DSS/CCKAirtimeconsumption

OFDMAirtimeconsumption


Low rates impact Depends on frame size…

CCK DSSS OFDM

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

1 2 5.5 11 6 12 24 36 48 54 130 300

64 Byte

128 Byte

256 Byte

512 Byte

1024 Byte

2048 Bytes

Time/

μS

Mb

ps Frame

Size/Bytes

OFDMCCKDSSS

Codec & Bit

Rate

Time

consumption

per voice flow

at 1 Mb/s

Time

consumption

per voice flow

at 24 Mb/s

Time

consumption

per voice flow

at 54 Mb/s

G.711

(64 Kb/s) 102.4 ms 9.45 ms 6.49 ms

G.729

(8 Kb/s)46.4 ms 6.27 ms 5.20 ms

G.726

(32 Kb/s) 70.4 ms 7.27 ms 5.64 ms

G.728

(16 Kb/s) 42.43 ms 4.72 ms 3.74 ms

Individual theoretical time consumption:

SLOT + DIFS + (voice packet + headers) x speed x (number of packets per second) + SIFS + ACK


And most BYODs know that

Most BYODs take advantage of 802.11 blocks to group small frames (even if they end up sending one frame at a time):

Viber on Iphone 5S

Viber on Samsung S5


What should be your Minimum rate?

40

You want to stop your cell in a place where the following happens:

Signal to your clients is still strong

Clients and overhead traffic still “reasonably fast”

Retries are low

Beyond that point, clients should be able to get to another AP if they want to. On the right:

STA1 and STA2 hear each other -> less collisions

STA 1 and STA2 send @ 54 Mb/s -> short delays

STA3 is far from AP -> lower data rate (longer transmission delay), higher PER and loss risks

STA3 does not hear STA1 and STA2 -> higher collision risk

54 Mbps

6 Mbps

STA1

STA2

STA3


What should be your Minimum signal level?

41

Multiple measurements show a “sweet spot” by -67 dBm:

What minimum configured data rate is that? Depends…

802.11n client still communicates at 72 Mbps (MCS 7)

Management/control frames still sent fast (24 Mbps)

But you start seeing devices (here the AP) dropping rate because signal starts to degrade


What should be your Minimum data rate?

42

And BER is important, because more retries means more chances that the frame will be dropped

Your job is to limit frame drops to1% or less to maintain 4.1 MOS

At -67 dBm RSSI, SNR istypically around 25 dB or more*

You can run any rate of 24 Mbpsand up, and still have good frame success rate

* well, at least in ideal conditions… see next slides


Signal Attenuation

Your hand position may make things worse

Object in Signal PathSignal Attenuation

Through Object

Plasterboard wall 3 dB

Glass wall with metal frame 6 dB

Cinderblock wall 4 dB

Office window 3 dB

Metal door 6 dB

Metal door in brick wall 12 dB

Phone and body position 3 - 6 dB

Phone near field absorption Up to 15 dB

There can be a 20 dB difference between these photos


Let’s do the signal level math

-67 dBm

-67 – 20 = -87 dBm

Signal is too weak…

APAP

But you can roam to the other AP @ -67 dBm!


BTW, where do you put an antenna on a BYOD?

45

Head – not good

Hand – not good

HTC One, whole

back cover is metal and

antenna

Iphone 5,

Antenna is at

bottom

Samsung S5, antenna

is at bottom, behind button


Disable 802.11b but not 802.11n low rates!

46

Each SSID will advertise at the minimum mandatory data rate

Disabled – not available to a client

Supported – available to an associated client

Mandatory – Client must support in order to associate

Lowest mandatory rate is beacon rate

Highest mandatory rate is default Mcast rate


Disable 802.11b but not 802.11n low rates!

47

Many BYODs rely on the beacon to validate that the

AP is still there (and sync their clock)

Many BYODs also ignore AP instructions about

supported 802.11n rates (disable them, and your

client talks at a speed the AP will ignore)

In standard density environment, stop your cell @ -67 dBm.

When power is @ 11 or 14 dBm, this is about 12 MbpsEverything below 12 Mbps is disabled

(but NOT 802.11n low rates)

First allowed rate (12 Mbps) is mandatory


Cell size strategies

In HIGH density environment, also stop your cell @ -67 dBm.

Power is usually low, 14 dBm or lower

Cells are smaller than in standard density environment

Roaming occurs faster

Rate @ -67 dBm is more commonly 24 Mbps

You want to allow your client to roam at that point -> 24 Mbps is set to Mandatory (below 24 Mbps, client does not hear the beacons and typically scans to find alternate AP)

You still want the client to communicate with the AP while getting into panic scan

Set lower rates (18, 12 Mbps) to Supported


Disable Slow rates, and maybe fast rates!

What about the other rates?

For Voice, rates faster than 24 Mbps do not bring any clear advantages

Codec & Bit

Rate

Time

consumption

per voice flow

at 1 Mb/s

Time

consumption

per voice flow

at 24 Mb/s

Time consumption

per voice flow

at 54 Mb/s

G.711 (64 Kb/s) 102.4 ms 9.45 ms 6.49 ms

G.729 (8 Kb/s) 46.4 ms 6.27 ms 5.20 ms

G.726 (32 Kb/s) 70.4 ms 7.27 ms 5.64 ms

G.728 (16 Kb/s) 42.43 ms 4.72 ms 3.74 ms

Time consumption = SLOT + DIFS + (voice packet + headers) x speed x (number of packets per second) + SIFS + ACK


Disable Slow rates, and maybe fast rates!

Faster rates DO have an impact on rate shifting:

200 byte frame @ 54 Mbps is sent in 3.7 μs

200 byte frame @ 24 Mbps is sent in 8.3 μs

Rate shifting from 54 Mbps to 24 Mbps wastes 1100 μs(65 times longer to send the next frame), in ideal (no congestion) conditions

54 Mbps

48 Mbps36 Mbps24 Mbps

54 Mbps

36 Mbps

24 Mbps


Disable Slow rates, but not 802.11n rates!

51

Conclusion: disable low rates

If your real time applications are Voice only,

disable rates higher than 24 Mbps, and set

channels to 20 MHz

If your real time applications are Voice AND

Video, then you need higher rates

In 5 GHz, set channels to 40 MHz… if your

clients support 40 MHz

Leave all 802.11n / ac rates enabled

(if your clients support 802.11n and 802.11ac)

Cell Size - 20, 40, 80 MHz?


Cell Size – Depends on Power, Protocol and Rates

53

With the explosion of 802.11ac, majority of devices are dual-band

98% of devices observed are 802.11n

5 GHz 802.11n devices are not always 40/80 MHz-able

0.1

38 40

55

29

5060

99

62 60

45

71

5040

0

20

40

60

80

100

1205 GHz


Cell Size – Depends on Power, Protocol and Rates

54

What about YOUR network?

If there is no network deployed yet, capture traffic at different times and observe

Example: large airport on US East Coast, last month 12 captures of 10 minutes each at different times / days, with wireshark – display rates

In this network, enabling 40 MHz is a waste40 MHz rates

20 MHz rates

AP Placement Strategy


Real Time AP Placement

56

A huge percentage of problems come from incorrectly defined coverage areas

Coverage areas: where the real time service should be offered

Typical errors: “not needed in the bathrooms”, “not in the elevators”, “not in the stairs”, “not in the outdoor smoking area”

Talk to end-users. Think what they will need and when

Coverage Areas


AP Placement Guidelines

Mount APs so that antennas are vertical (we use vertical polarization)


AP Placement Guidelines

Avoid metallic objects that can affect the signal to your clients


RF Design Matters

62

Highly reflective environments

Multipath distortion/fade is a consideration

Legacy SISO technologies (802.11a/b/g) are most prone

802.11n improvements with MIMO

Devices are susceptible

Things that reflect RF– Irregular metal surfaces

– Large glass enclosures/walls

– Lots of polished stone


AP Placement – Bad Examples

Issue is sometimes in the environment

Ceiling is highly reflective

metallic mesh

AP behind ceiling

(yes they did that)


AP Placement – Bad Examples

AP too high:– Low rate to the ground

– Client signal too weak at the AP level

> 20ft

Nice… but you won’t cover the

jetway as soon as the door closes


AP Antenna Guidelines

Use matching antennas

When RF cluelessness becomes art…

These are dual band plugs (2.4 and 5 GHz)

They require dual band antennas… they are labelled “a,b,c,d”

These are single band antennas…

are you going to get 2.4 or 5 GHz? Antenna gain mismatch: AP

won’t know which to believe

Coverage pattern mismatch:

Are you covering through the

wall?

Taking Care of the Roaming Path


Rates and Cell Overlap

Cell overlap is designed so that when a VoWLAN device gets to the

–67 dBm area, it is already in good range of another access point.

20-percent overlap between cells is recommended

How much is that? Use the -75 dBm rule if you are not sure.


Network Design

70

Try to design small cells, with clever overlap…


Channel Plan and Data Rate

Each cell’s useful radius is determined by the minimum allowed data rate

RF

edge

24 Mbps OFDM36 Mbps OFDM48 Mbps OFDM54 Mbps OFDM


Client Signal Detection Optimization

AP Rx sensitivity is MUCH higher than that of most BYODs… and improved over the years beyond the 802.11 requirements

E.g. 1242 Rx sensitivity at 1 Mbps is -96 dBm, with a typical SNR of 3 dB (so you need -96 dBm signal, with background noise not more than -99 dBm, to recognize and read a frame sent at 1 Mbps). With the 3700 AP, that threshold is -101 dBm (with the same SNR requirements), so we are 5 dB better

We need more signal to read 802.11n than legacy protocols. If we disable legacy protocols on our new APs, the problem would probably more or less go away by itself, but the issue is that we keep the old protocols and at the same time build smaller cells to benefit from the additional throughputs.

Rate Recommended RSSI (3700AP) Recommended SNR

1 Mbps -91 dBm 1

6 Mbps -87 dBm 2

MCS 0 (6.5 Mbps) -82 dBm 1


Sending modulation depends on Received RSSI and SNR

74

802.11 determines “minimum RX performance values” – RSSI based

Vendors achieve “at least” these values

Example: Cisco 3700e Rx performances:


RX-SOP – (Receive - Start of Packet) – What is it?

75

Receiver Start of Packet Detection Threshold (RX-SOP) determines the Wi-Fi signal level in dBm at which an AP radio will demodulate and decode a packet.

The higher the level, the less sensitive the radio is and the smaller the receiver cell size will be

By reducing the cell size we can affect every thing from the distribution of clients to our perception of channel utilization

This is for High Density designs – and requires knowledge of the behavior you want to support

A client needs to have someplace to go if you ignore it on the current cell

WARNING – This setting is a brick wall – if you set it above where your clients

are being heard – they will no longer be heard. Really.


RX-SOP configuration

76

Settings High, Medium, Low, Auto

Auto is default behavior, and leaves RX-SOP function linked to CCA threshold for automatic adjustment

Most networks can support a LOW setting and see improvement

This affects all packets seen at the receiver


Radiation Pattern and Roaming Buffer

When users are expected to roam while communicating, make sure their BYOD can detect neighboring APs BEFORE roaming

Directional vs omnidirectional antenna

Floor

AP signal drops fast

AP signal drops slowly

User does not have much space/time

to find the next AP


VoWiFi Rate Shifting and Transition AP

79

1

3

2A B

C

At “A” the phone is connected to AP 1

At “B” the phone has AP 2 in the neighbor list, AP 3 has not yet been scanned due to the RF shadow caused by the elevator bank

At “C” the phone needs to roam, but AP 2 is the only AP in the neighbor list

The phone then needs to rescan and connect to AP 3

– 200 B frame @ 54 Mbps is sent in 3.7 μs

– 200 B frame @ 24 Mbps is sent in 8.3 μs

– Rate shifting from 54 Mbps to 24 Mbps can waste 1100 μs


VoWiFi Rate Shifting and Transition AP

80

AB

C

1

2

3

At point A the phone is connected to AP 1

At point B the phone has AP 2 in the neighbor list as it was able to scan it while moving down the hall

At point C the phone needs to roam and successfully selects AP 2

The phone has sufficient time to scan for AP 3 ahead of time


Controller Redundancy and Roaming Paths

Design expected roaming paths and make sure all APs connect to the same controller, and overlap allows for next AP discovery


Avoid Ping Pong Zones

Ping-pong effect occurs when a wireless client is at the edge of two cells

and hops between them.

Client stays here


Avoid Ping Pong Zones

“Pacing back and forth” zone

Ping Pong zone recipe:

Set overlap along pacing path

Let user head force the roam


Cisco ClientLink Technology• Advanced Beam Forming Technology

84


BandSelect – Test Before Full Deployment

90

Caveat – Possible Increased Roaming Delay2.4G band

5G bandNo Delay

Some Delay

(1.5s)

Possible Delay

Client and AP 802.11 Optimizations


Cisco VideoStream - How Does it Work?

.

.

1

2

34

5

67

8

9

1. Client sends IGMP join

2. WLC intercepts IGMP join

3. WLC sends AP RRC request

4. AP sends RRC response

5. WLC forwards join request

6. Multicast sourcesends IGMP join response

7. Multicast stream sent

8. WLC forwards multicast stream to AP

9. AP converts stream to unicast and delivers to client

98


Thinking BANDWIDTH in Terms of Directions

102

In a standard cell, 70% of traffic is downstream (from AP to client)

30% is upstream

We can definitely control downstream, especially as 802.11n/ac stations are necessarily WMM

Can we control the upstream? Not directly, but we may have an indirect way of controlling it…

Don’t

send!

I decide, alone,

when to send (thank

you CSMA/CA)

10

2


Bandwidth Control

103

You can also control upstream and downstream bandwidth consumption:

Per QoS Profile (Gold etc.)

Per SSID

Per user type (guest etc)

Per device type

Per individual user


If you have Several Traffic Types to Target: Use Application Visibility and Control

107

Identify Applications using NBAR2

VoiceVideoBest-Effort

Background

Client Traffic

Control Application Behavior

Don’t Allow

Rate Limiting

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Last Words - Troubleshooting


Troubleshooting Tools

112

Wireless sniffer

Omnipeek/Wireshark (multichannel, for roaming issues)

Mac with OS X 10.6 and above, Windows 7 with Netmon 3.4

AP in Sniffer mode

L1 analysis: SpectrumExpert

WLCCA (WLC Configuration Analyzer) – TAC support

NCS / Cisco Prime Infrastructure for Historical viewand « Client Troubleshooting tool »

Wireless Captures, RF Analysis, Configuration Analysis


Support Community

113

https://supportforums.cisco.com/community/5771/wireless-ip-voice-and-video


Continue Your Education

• Demos in the Cisco Campus

• Walk-in Self-Paced Labs

• Table Topics

• Meet the Engineer 1:1 meetings

115


Call to Action

• Visit the World of Solutions for

– Cisco Campus

– Walk in Labs

– Technical Solution Clinics

• Meet the Engineer

• Lunch time Table Topics

• DevNet zone related labs and sessions

• Recommended Reading: for reading material and further resources for this session, please visit www.pearson-books.com/CLMilan 2015

116

http://www.pearson-books.com/CLMilan 2015


Complete Your Online Session Evaluation

• Please complete your online sessionevaluations after each session.Complete 4 session evaluations& the Overall Conference Evaluation(available from Thursday)to receive your Cisco Live T-shirt.

• All surveys can be completed viathe Cisco Live Mobile App or theCommunication Stations

117

design and deployment of wireless lans for mobile...

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