CCNP Wireless Deploy (300-365)

The following information is for anyone that is looking at or is currently studying for the CCNP Wireless Deploy (300-365) exam.

Information about the CCNP Wireless exams can be found here as well there is a CCNP Wireless study group

Study material is limited but I have listed what is available below, the best thing is to do given the limited official study material is breakdown the exam blue print and mark the sections of as you become confident in the topic.

Study material:

  • Cisco deployment guides based on the code version of the exam
  • Cisco CCNP wireless Quick reference guides

For this exam you will need to buy or borrow some lab equipment, so to ensure you grasp the topic’s in the blue print.

Equipment at a minimum:

  • 2x 2504
    • Can do most WLC configurations expect HA SSO and rate limiting
  • 4x 3502 or better
    • Can re-image 2 for Autonomous AP studies
  • Server that is able to run Prime, ISE, windows server, and windows client

This will enable you to do a lot of the topics in the blue print.

I sat the exam on March 2019, and passed on first attempt with about 20minutes of spare time left over.  Same with the CCNP-W Design exam the Deploy exam has the typical Cisco question, where it could have two right answer but the correct one depends on what document you read.

The exam does have configuration/troubleshooting questions as well as lab simulations in it, so hands on experience is a must if you aim to pass.

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CCNP Wireless Design (300-360)

The following information is for anyone that is looking at or is currently studying for the CCNP Wireless Design (300-360) exam.

Information about the CCNP Wireless exams can be found here  as well there is a CCNP Wireless study group

The following material below is what I would recommend for anyone looking at studying for this exam

Study material:

CWNP: Certified Wireless Design Professional study guide (CWDP-302)  https://www.cwnp.com/certifications/cwdp

Cisco CCNP Wireless CUWSS Quick guides

  • Old book, yes but so is Cisco wireless design methodologies

Cisco E- learning

Cisco deployment guides based on the code version of the exam

In Nov 2018, I sat the CCNP Wireless Design (300-360) exam and passed it, I finished the exam with plenty of spare time. The exam had typical Cisco question, where it could have two right answer but the correct one depends on what document you read.

The exam was based on a lot of Cisco best practices and wireless standards, if you have been doing Cisco Wireless or wireless design in general for some time you may find the exam not that difficult. If you haven’t I suggest reading the material mentioned above and visiting the CCNP Study group linked above.

How many clients can we have per radio?

A very common question we wireless professionals get asked is. How many clients per AP can we have on this AP?

To help us determine and better answers this question there are some excellent resource available that I have linked below. Highly recommend becoming familiar with them.

Capacity Planner by Andrew Von Nagy at Revolutionwifi

Forecasting AP Capacity by by Andrew Von Nagy at Revolutionwifi

Wi-Fi Throughput by Devin Akin at Divergent Dynamics

Ekahau Site Survey Pro (any of the latest version) need to pay for software

Client information by Mike Albano at mikealbano.com

To determine client capacity, we need to understand what is actually possible, as we have some major limiting factors with our wireless networks “Air-time” and the half duplex nature of the medium.

Capacity calculators like the ones above are used to determine how many AP’s/Radio’s we need based on the amount/types of clients and their throughput requirements.

To get a general understand of how many clients a radio can support I will show some examples using Devin Akins efficiency rules (linked above) “MCS rate x ~ 40% / # of users = per device throughput.

Following examples are based on zero 802.11 and non-802.11 source of interference (perfect world).

Example 1:

802.11n 2×2:2 AP with 20MHz channel with 50/30/10 802.11n 1×1:1 clients at an RSSI -64 that gives them a MCS7 data rate of 72Mbps with a short guard interval at medium/large use.

Data Rate= 72Mbps

40% efficiency= medium/large use

Total throughput capacity= 29Mbps

/50 1×1:1 client devices =570Kbps/client

/30 1×1:1 client devices =650Kbps/client

/10 1×1:1 client devices =2.9Mbps/client

Example 2:

802.11n 2×2:2 AP with 20MHz channel with 50/30/10 802.11n 2×2:2 clients at an RSSI -64 that gives them a MCS7 data rate of 144Mbps with a short guard interval at medium/large use.

Data Rate= 144Mbps

40% efficiency

Total throughput capacity= 58Mbps

/50 2×2:2 client devices =1.152Mbps/client

/30 2×2:2 client devices =1.92Mbps/client

/10 2×2:2 client devices =5.76Mbps/client

The following examples show the affect that device capability & number has to overall throughput per client.

Wireless networks 99% of the time contain different chipsets, understanding your device types is a critical component to your wireless network. Mike Albano site has an extensive list of different client chip sets, if the device is not listed, it mentions how to capture the information.

A very common way marketing spin their AP’s is with descriptions like: “Our 802.11n 2×2:2 APs can support 500 clients with a data rate of 300Mbps”. Which is just not possible.

Why?

  1. To theoretical achieve a “data rate” of 300Mbps you need to have 40MHz wide channels, clients are 2×2:2 802.11n with an RSSI -64dBm using a short guard interval.
  2. The term “data rate” is completely miss leading this is not your actually throughput, wireless has a lot of overheads, basically cut that value in half and there is your starting point.

Now let’s look at some other variables that also affect the capacity of our wireless networks

  1. Business requirements:
    1. Different applications have different channel utilisation threshold before services start being affected
    2. If Voice services are required what are the RF design and configuration requirements,
      1. RF design
      2. Vendor specific configuration requirements: i.e. Cisco CAC
  2. QoS design
    1. Such as 802.11e, WMM, DSCP & CoS
  3. Rate limiting
    1. Can have significant impact to air-time utilisation
  4. Airtime fairness
  5. # of SSIDs
  6. % of associated users or concurrent clients?
  7. AP’s configuration i.e. 1x 2.4GHz and 1x 5GHz
  8. AP Chips sets, can they handle all the con-current and client associations
  9. Sources of RF and non-RF interference
  10. Wireless design requirements: Mesh with client connect, etc.
    1. Mesh present a whole number of extra requirements (headaches) when considering overall aggregate throughput per client.
    2. Channel plan
    3. Suitable Channel width without increasing CCI & ACI
  11. Device types, density, & number of devices:  A killer especially with legacy devices.
  12. Client device drivers are up to date.
  13. Backhaul: extremely important.

While an AP data sheet may say it can support # of clients per radio, we as wireless engineers need to ensure our wireless networks are designed with sufficient AP density to accommodate the numbers/types of clients and their throughput requirements.

Capacity planning is critical step to ensuring the wireless network meets the requirements of the design.

CCA from Another Perspective

As we know 802.11 is half-duplex, so devices must check the wireless medium to determine if it is free or busy before it can send traffic, No issues there.

Where it gets interesting is when we look at the thresholds (at a high level) that determine if the medium is busy. Part of the mechanism used to determine if it is available is called Clear Channel Assessment (CCA). Within CCA there are two thresholds – Signal Detect (SD)and Energy Detect (ED).

–          Signal detect (SD): listen for any transmitting 802.11 frames

–          Energy detect (ED): list for any other none RF transmissions that is 20dB stronger than SD (won’t go into this in this post)

SD is used to detect a transmitting 802.11 preamble, which is contained within the physical layer header of an 802.11 frame, if it can decode the preamble, it will attempt to sync with the incoming transmission, which is sent at the lowest basic rate for the Band, 1 Mbps for 2.4GHz and 6Mbps for 5GHz. The SD threshold is usual set at 4dB SNR, so if the noise floor is at -96dBm, an 802.11 device is able to demodulate the preamble at an RSSI of -92dBm, which would then trigger CCA, causing devices to deferrer.

So how far is -92dBm or 4 dB SNR? The below simulation shows you how far, represented by a simulated Cisco 3802 AP with the following configuration: 1mW,2.4GHz and no obstruction,

The colour coding represents the following signal areas,

Screen Shot 2019-03-21 at 7.34.00 pm.png: The wireless coverage we have designed for, where we want our clients to be associated

Screen Shot 2019-03-21 at 7.34.06 pm.png : The area that can cause CCA

and every where else is where it becomes noise below the required CCA threshold

Screen Shot 2019-03-21 at 7.37.22 pm.png

  • Note the picture above is only the Radius.

Using 1mW (equates to 0dBm) and with a cell edged measure at -92dBm the total distance is 500m.

In some of the environments that I work in our industrial wireless AP can vary anywhere from 2Watts (33dBm) – 4Watts (36dBm) in the 2 .4GHz and 5GHz band and our enterprise AP around 25mW (14dBm) +/-, so the potential coverage area for SD to cause devices to deferrer can be quite large

Understanding this is important when it comes to our wireless designs. We design for a required cell edge i.e. -67dBm/25dB SNR for devices, but we also need to account for the signal we don’t care about as it continues on, so we can minimise Co- channel interference (CCI).

Minimising CCI is possible in 5GHz (depending on AP capacity), but not possible in 2.4GHz. It becomes an even greater pain in the butt when we add client STA’s into the mix, as the client STA are one of the biggest contributors to CCI.

Screen Shot 2019-03-21 at 7.38.27 pm.png

While we may have done our best to minimise AP CCI, as soon as a mobile client roams to the outer edges of a cell, it has the potential to extend the contention domain and interfere with another AP on the same channel, causing devices to defer. This is due to SD as mention previously

This in turn increases medium contention, due to devices having to defer, which eats up your airtime – equaling less throughput.

What can we do to help reduce this?

  • Understand your AP and client STA receive sensitivities levels
  • Consider your CCI boundaries in your designs
  • Use directional antennas where possible

Would like to give a shout out to two legends @WazzFi and @Stephen_Cooper for their input and support.

Reference:

Tom Carpenter (2016). Certified Wireless Analysis Professional (CWAP-402). US: CertiTrek Publishing

https://blog.aerohive.com/what-is-clear-channel-assessment-cca/

Devin Akin (2018) Certified Wireless Design Professional Training course

 

The importance of physical AP separation

The following information is to highlight the negative impact that occurs when AP’s are installed next to each other <3m, as It is not uncommon in today’s wireless deployment, to see these types on installations.  As the old saying goes a picture paints a thousand words, so I have tried to minimise technical jargon, by using pictures.

Figure 1, shows the spectral mask (Shape) of an OFDM modulation pattern, which will be represented throughout. An OFDM spectral mask, is approximately 20MHz wide, and is based on the centre channel. In this example it is based on channel 6.

 

Screen Shot 2019-01-30 at 10.37.04 am.png

Figure 1: OFDM Spectral mask

 

The Spectral mask of any 802.11 modulation contains certain key areas,

  • Peak power
  • Shoulders
  • And where it tapers off into background noise

 

All have values which are described as decibels relative to peak power (dBr) of the centre frequency

Good design practice is to ensure only non-overlapping channels are used. In the 2.4GHz band to be consider non-overlapping it must be separated by 5 channels or 25 MHz, in the 5GHz band it is 20MHz separation from the centre frequency.

Not only is having non-overlapping channels critical to any good wireless design, so is the importance of AP separation. If AP’s are not physically separated >3m or have some form RF isolation method than interference will occur. This also applies to AP placement when located next to objects, but sometimes this is unavoidable, so correct antenna selection is crucial.

To demonstration this I have setup the following equipment in a small lab scenario as shown in Figure 2, AP1, 2 & 3 at approximately less than 30cm apart, configured on static channels 1, 6 & 11, at transmit power of 20dBm This testing is relative to the equipment used) Spectrum analyser sitting next to the AP’s to view the layer 1(RF) information

Not shown in this picture are test clients, 3x 1×1 Apple IPad mini and Apple MBP that will be used for throughput testing and capturing information.

 

Screen Shot 2019-01-30 at 10.38.04 am.png

Figure 2:  Lab setup

Shown below in Figure 3. Is the current 2.4 GHz band utilisation.

Screen Shot 2019-01-30 at 10.38.12 am.png

Figure 3: 2.4GHz band before testing

AP1 is enabled on Channel 1 with a client device conducting a throughput test, as shown in figure 4.

Pay particular attention to;

  • The shoulders of the OFDM spectral mask, notice how it bleeds over into adjacent, and non-overlapping channels.
  • Notice the channel utilisation, for adjacent and non-overlapping channels.

Screen Shot 2019-01-30 at 10.38.20 am.png

Figure 4:  AP1 on Channel 1 with client running throughput test

I will now disable AP1 and repeat the same test again this time with AP2 on channel 6

Screen Shot 2019-01-30 at 10.38.27 am.png

Figure 5:  AP2 on Channel 6 with client running throughput test

This time leaving AP 2 still enabled, I will re-enable AP1. Notice that the shoulders of both the spectral masks have bleed together.

Screen Shot 2019-01-30 at 10.38.32 am.png

Figure 6: AP1 on channel 1 & AP 2 on Channel with throughput testing being conduct with Clients

Now compare the channel utilisation from figure 5 to figure 6, notice the increase that has occurred.

AP 2 is disable and AP3 is enable on channel 11 also with a client conducting a throughput test

Screen Shot 2019-01-30 at 10.38.36 am.png

Figure 7: AP1 & AP3 with throughput testing being conduct on each channel

Figure 7 shows utilisation occurring on channel 6 regardless of any stations. Take note on the channel utilisation in figure 7 and compare it figure 5. The utilisation on channel 6 in figure 5 is almost the same as figure 7.

This time I will re-enable AP2 with client. Take note of the overall increase in 2.4GHz band utilisation and the shoulders of the individual spectral masks.

Screen Shot 2019-01-30 at 10.38.45 am.png

Figure 8: AP1, 2 &3 enabled with clients running throughput tests

Now let’s compare the difference when AP’s are physically separated.

AP1 and AP3 are separated by 5meters, the spectrum analyser is located in the middle

Screen Shot 2019-01-30 at 10.38.51 am.png

Figure 9: AP 1 & 3 separated by 5m

Notice the spectral mask shoulders and overall channel utilisation of the band compared to previous test shown in figure 6.

This time I have changed the channels but the distances remain the same.

Screen Shot 2019-01-30 at 10.38.56 am.png

Figure 10: AP 1 & 3 enabled with throughput test

Compare figure 10 against figure 6. Massive difference. All 3 AP’s are now separated by distance of 5meters.

Screen Shot 2019-01-30 at 10.43.11 am.pngFigure 11: AP1, 2 & 3 enabled with throughput test an AP’s

Notice the difference in overall utilisation when figure 11 is compared to figure 8.

Hopefully this shows that physical separation is extremely important to minimise interference, however testing should always be performed as the distance required is dependant to the AP, antenna and EIRP selected. To determine the required separation  those factors must be account for.

As mentioned this was a small test lab, if this was in production the impact would have been magnified.

 

 

 

 

 

Certified Wireless Network Expert

Certified Wireless Network Expert (CWNE)

CWNE.png

The purpose of the blog post is to discuss my journey towards becoming a CWNE and the  common questions I get asked.

 

CWNE certification is the finale step in the CWNP certification track. For more information about what CWNP offered and the CWNE certification requirements I have added the link below.

https://www.cwnp.com/certifications/cwne

I have done up some pervious blog posts on my journey with the CWNA and CWNP certifications, links are posted below.

https://wordpress.com/post/wifiburns.wordpress.com/281

https://wordpress.com/post/wifiburns.wordpress.com/686

In April 2018  after a gruelling  4months of waiting since submitting my CWNE application, I received the email congratulating me that I have successfully become CWNE#269, once I read the email I jumped out of my chair and repeatedly fist pump the air.

Screen Shot 2019-01-04 at 11.00.05 am.png

Why did I decided to embark on this journey?

  • It made perfect sense given my passion for wireless, experience, current job role and responsibilities.

How long did the process take?

  • Having achieved certain requirements already, such as vendor certifications, experience etc. It took around 12 months to complete the exams and application. Normal process is around 3 years minimum.

What order did I complete my exams in?

  • CWNA, CWDP, CWAP, & CWSP. There is a lot of talk about doing it in the following order CWNA, CWAP, CWSP & CWDP, and there is logic to this, but I did it in the order of topics I found the most interesting.

What exam did I find the hardest?

  • CWSP, I didn’t find the exam hard, just trying to stay motivated to study for it was difficult.

When did I start working on my CWNE application?

  • When I started studying for my last exam (CWSP).

What did I write my essays on?

  • Analysis, design and security, this seems to be the normal approach

How many words where my essay’s?

  • Keeping your essay in the minimum and maximum word count is difficult. I included pictures which added more pages to each essay. But overall I think they were around 1500 words, there is talk that it should be less.

What  vendor certifications did I use as part of my application?

  • CCNP R & S
  • CCDA

How did I submit my application?

  • I submitted my application via email, by attaching the individual sections of the application. Note there is a lot of people on the CWNE board so your formatting or structure of your application may not be preferred by some members.

Would I recommend CWNE certification?

  • It depends, on you own personal circumstances, such as experience, career goals,  current job etc. For me it made perfect sense and has greatly benefited my career.
    • I do strongly believe anyone working with 802.11 networks should hold a CWNA certification.

Any misc. tips?

  • Get a CWNE mentor, I was extremely lucky to have the opportunity to work with a 2xCCIE and CWNE over the period of 2017. In Australia CWNE’s are rare as hens teeth.
  • Get fellow peers to review your application.
  • Don’t rush it.
  • Prepared to wait a few months to get the final response on your application. The CWNE board is volunteer based.
  • If you don’t get an email saying your application has been received email until you do.
  • Get solid referrers:
    • I think it should be mandatory that one is a CWNE, that can validate your work ethic and knowledge.
  • Remember your application needs to sell you as a wireless expert.
  • Be active in the Wireless community, The wireless community in Australia is tiny and its even smaller when you exclude the wireless people that have no idea what they are doing 🙂 so  reach out, get involved in
    • Twitter
    • Slack
    • Wireless LAN association
    • Forums
    • Blogs
    • youtube

Hope this post has been able to provide some answers to the common questions I get about the CWNE certification.

 

 

 

 

 

 

 

Part 2 Issue with deploying enterprise wireless in the mining industry

 

This is continuing on form Part 1 which can be found in the below link

Issue of deploying Enterprise wireless in the Mining environment Part 1

 

The aim of this blog is to highlight some of the common issues that I have faced when designing and installing enterprise wireless network in the mining industry.

Wireless technology deployed on sites is Cisco.

A picture paints a thousand words, so I am going use them as part of my explanations.

AP Placement:

IMG_1199

Picture: one CAT795F dump truck in a 8 bay garage

Picture above, highlights many issues I face with Antenna selection and AP placement.

  • Overhead mobile cranes systems, can dislodge APs or cause shadow zones
  • Heavy vehicles (massive tonka trucks)
  •  Insulation on walls and roofs. Antenna selection and AP placement consideration need to be taken into account to avoid excess reflections

Part 3 will doing into the specific of AP placement.

 

 

IMG_5337.JPG

Picture: CAT797B dump truck (RF Killer)

Cabling

IMG_1205.JPG

Picture 2: Cable trays

Running data and power cabling can be a very costly exercise given the size and structural design of the locations most installation required specialised equipment to be hired such as scaffolding, mobile elevated work platforms and at time cranes. All  equipment needs to be mine rated and requires  permits and license to operate.

Existing cable trays are often used for LV and HV cabling so alternate paths are need for data.

Locations

 IMG_0290.JPG

Picture: Coal wash plant

Certain locations where client devices may operate are extremely problematic for RF propagation and AP installation, sometimes the customer may need to be educated and shown an alternate solution as ubiquitous coverage is not always  possible in certain environments as well considering the cost.

IMG_1845.JPG

Picture: Water plant

  • AP’s require maintenance, due to getting covered in material$$$
  • AP’s require specialised  engineered mounting brackets due to excessive vibration
  • AP life span is reduce due chemicals and material in area.

Some site contain locations that  are rather old and contain asbestos which can be a headache for the installation of cabling and AP’s

Point-to-point

Locations can be remote with no connection back to the main site, so a P2P link sometimes is required, but over time the link stops working and you discover that the mine has decided to put a massive stock of ore which once use to be road that now blocks the link.

Rogue Networks

Mine site use wireless mesh network for there production networks and mobile fleets, technologies suchs as Rajant and TropOS are the most common I have seen, which can operate up 4watts.

IMG_0092.JPG

Picture: Rajant Breacrumbs Antennas installing workshop

Apart form the ACI and CCI issue they can cause, some locations  have business SSID being broadcast over the mesh network. When a fleet vehicle enters a non-production are it can cause client connectivity issues given the EIRP and client behaviour. A simple solution would be to remove it from SSID form the meshed network but nothing is simple.

Contracting company’s  install there on wireless networks, most of the time its with the default 80MHz wide channels.

Mice

Mice eating newly installed fibres, this occurs often over the winter period. To install mice traps etc. requires approval which can be difficult depending on sitemice eat fibre.PNG

Picture: Mice have chewed fibre( notice the paw prints and mice shit).

 

Part 3 will address AP placement and considerations  to provide wireless coverage based

Part 1: Issue of deploying Enterprise wireless in the Mining environment

The purpose of this blog post is to highlight some of the issues that I have faced over the past 6 years of trying to deploy enterprise and non enterprise wireless solutions in the mining industry.

Given the need for mobility,  guest access  and the demand for increased productivity, I have seen a dramatic increase in enterprise wireless networks being deployed in the mining industry.

dit.PNGPicture: Coal Mine

The mining industry is  a complex harsh beast. There are extremes of both hot and cold weather,  shift work, long 12-14hr days in environments where safety keeps you alive. Locations  are remote, some of the mines are hundreds or thousand of miles from the nearest town. Aside from the work environment, there are a great deal of  challenges and hoops one must jump through before even getting on to site.

For instance one cannot simply walk around with their Laptop and collect information easily, compared to an office environment ( love those surveys)

Each mine site has different access and safety requirement before you can enter  site and subsequent areas.

Things  that are common:

  • Site and area specific Personal Protective equipment (PPE)
    • Depending on the PPE requirements can make it rather difficult to conduct a WSS .
      • At minimum it is always
        • Hard hat
        • Eye glasses
        • Ear protection
        • Gloves( sometimes you have 2-3 different pairs)
        • High visibility clothing , long sleeved and pants
        • Steel cap lace up boots (some sites have specific boots to wear that are issued in location)
        • at worst, I have had to wear a full face respiratory system in the hot Australian summer  (could not see shit).
  • Site and  area specific inductions
    • These can  be 1hr to a full  day depending on the area.
  • Safety inductions
    •  Sometimes require additional first aid training
    •  Electric safety awareness induction
    • Working at heights( (some roof heights are 30m+)
  • Work permits
    •  May be required to sign on or have to have  you own specific work permit generated. this again is time consuming as it requires approvals.

Once you have the basic out of the way,  you maybe able (I stress “maybe”  as you still need  approval by the on shift superintendent or supervisor) to enter the area and 99% time it is under escort.

In my experience floor plans provided are never correct.  Most of the time I have to draw them up or use evacuation plans located near fire exits (sometimes they are correct).

  • Given the time constraints and environment an APoS is not able too be performed in most cases

heavey.PNG

Picture: Heavy Vehicle workshop

  • Restricted areas:
    • production outage can cause millions of dollars per hour.   Miners will not stop working  so I  can walk around and collect some data points on a production piece equipment. All the time you stick to the designated walk way and collect what information you can.
  • Information gathering can be an issue as some locations have restriction on the types of equipment that is allowed into an area.  So a note pad and pen is all you have and given these environments are  extremely dirty, muddy and wet,  you need to ensure you look after (Zip lock bag) your gear. There is limited chance of  a second bite of the cherry if you forget to get the switch model number/details and communications cabinet number.

dustry.PNG

Picture: Dusty areas

cisco.PNG

Picture: standard comms cabinet out in the field (not one of mine)

  • Damage to equipment
    • As mentioned before these environments are dirty and  can be depending  extremely hot or cold  depend on the time of year. Your equipment is your life line, and it will get dirty. So far I have been lucky(or unlucky) and so far only damaged the screen on my Surface Pro 4. Still was able to use it complete WSS. Everything I have is stored in Pelican cases.

 

Picture: Pelican cases of equipment

case 3.PNG

Picture: Tripod

csae2.PNG

Picture: Couple of Pelican case when they were brand new.

damge.PNG

Picture: Damaged SP4 but still could charge on, used an iPad screen protector to keep it together.

Once you have completed the survey and collected all your required information, next comes the joy of trying to design the wireless network based on the environment and  wireless criteria.

Which I will discuss in my next blog post

CWNP (CWAP, CWSP, & CWDP) Certifications worth it

Is it worth undertaking the time and effort to achieve any of the CWNP Professional certification such’s as CWAP, CWSP and CWDP?

YES it is, without a doubt worth it.

After I complete my CWNA, I was wondering what certification track to embark on next, I was looking into CCNP wireless as I already hold a CCNA Wireless, and the company I work for is a Cisco shop.

However I decided to embark on the CWDP certification, as I was currently doing a great deal of wireless site surveys and designs, I also was very luck to have the opportunity to work on a project with a 2x CCIE and CWNE, which motivated me to not only study for my CWDP but also achieve the other 2 certifications and go for my CWNE, as he offered to endorse me, ( part of the application process to become a CWNE requires 3x endorsement one of which is highly recommend to be current CWNE) after 7 months of study I pass all 3 CWNP exams first time with 85% pass on all of them.

The order I completed the exams was CWDP , CWAP and CWSP this is not the most recommend way to complete the exams but suited my strengths and interests which is what I suggest.

The study time line is as follows

  • CWDP: just under 2 months
  • CWAP: just over 3 months
  • CWSP: just over 2 months

I spent on average 2-3hrs a day studying for these exams, while juggling university studies, family and work life.

my average Mon-Friday day consisted of the following while studying

  • 3:50am wake Up (caffeine lots of it)
  • 4:00am study  CWNP study
  • 5:00am  Exercise
  • 5:45am family/work routing
  • 7:00am study CWNP on train 50mins
  • 12:00pm lunch study CWNP 15mins
  • 4:30pm study on strain 50mins
  • 7:30pm study on CWNP and uni
  • 9:30pm Bed

Weekends

  • 5:00am wake Up (caffeine lots of it)
  • 5:15am study CWNP study
  • 8am-6:30pm family time/ go to the gym for 1hr
  • 7pm Uni study
  • 9:30pm Bed

when I had university assignments and exams coming up my daily routine was different as well life, work and kids always make things interesting but the above is the average.

The CWNP study guides are excellent and some of the best I have read. Exams as straight forward and if you know the material the question wont trick you up like some exams.

I actually found the CWSP exam the hardest out of all them, most say they find the CWAP the hardest, but for me it was not the case.

I can honestly say I really enjoyed studying for the CWNP certifications, as there is nothing worse  than having to read something you couldn’t give a rats ass about.

The knowledge and skills I learnt from this have greatly assisted me with in ever aspect of my job as a Wireless network engineer and I recommend the certifications to anyone.

Now that I have completed the CWNP track I will be applying for my CWNE which deserve a blog post on its own.

Mgig interface and Wave 2 AP’s

I was asked in a work team meeting by one of the network engineers part of the network refresh project about the Mgig interface on the new Wave 2 AP’s and if we should upgrade the switch interface to benefit from the information provided by the vendor data sheets

The below paragraphs is my attempt to explain to him and anyone else that would listen in the meeting that yes upgrading the switch and APs is a great idea, however based on good enterprise wireless design requirements and the nature of 802.11, we would not be able to achieve the theoretical wireless throughput rate of up to 5.2Gbp as per vendors data sheet.

To even come close to achieve this theoretical wireless data rate the AP requires to be configured with dual 5GHz radios (2.6Gbps per radio), both using 160MHz wide channels, and ideal RF conditions (RSSI greater the -48dBm and a Signal to noise ratio of above 40dB).

The major problem with this theoretical data rate is the channel width. In the 5GHz band we only have 25 20MHz wide non overlapping channels to play with (when using DFS Channels), If we where to utilise 160Mhz wide it only leaves us with 2.

Wireless is half duplex and given the mechanisms that an 802.11 device use to determine if the medium is free before sending traffic, having only 2 channels makes avoiding interference issue impossible. Client devices operating in a noise environment reduces the aggregate wireless throughput, due to the excess amount management traffic caused by corrupted frames being retransmitted ( more management traffic equals less data traffic).

When we design Enterprise wireless networks, a major design consideration is how to best design based on the RF spectrum available, frequency reuse, amount/type of client devices and data SLA, with these requirements identified we can determine the number of APs, placement and channel plan in order to avoid or reduce wireless issues such’s as co-channel, adjacent channel and overlapping basic service set interference.

Below are   some other reason why 160MHz wide via it not viable and won’t get the benefits of that Mgig interface in Enterprise Wireless deployment.

–           Currently no client devices support 160MHz wide channels

–           No normal wireless client device requires that amount of data throughput

–             Wireless Management and control traffic is sent a legacy data rates

–             Wireless is half duplex

–             TCP/IP overhead

–            Dual 5GHz AP deployments won’t work due to continued support for 2.4GHz clients.

–             When using the other radio as a 2.4GHz radio with a max 20MHz wide channel it has a  data rate of 288.9Mbps

–           Recommendations by a vendor for a dual 5GHz AP is 100Mhz spacing between channels, cannot use dual    160MHz wide channels are not able to be deployed.

–          Unrealistic RSSI and SNR values to achieve the MCS9 VHT Data rates

–         Multi-user multiple in multiple out (mu-mimo) but device need to capable and its only on the downlink.