CCIE Wireless · CCIEW Written

CCIEW – 1.3 Plan and design wireless solutions requirements

1.3.a Translate customer requirements into services and design recommendations

1.3.b Identify ambiguity and/or information gaps

1.3.c Evaluate interoperability of proposed technologies against deployed IP network infrastructure & technologies

This topic often comes down to common sense and experience. When you’re engaged by a business to either perform a site survey (next topic) or design a solution your key query to begin with will always be requirements.

Sometimes this will involve working with the client to assist both sides with understanding the requirements and, very importantly, the scope of what you will be undertaking. Scope creep is a common occurrence for any project and if there aren’t some agreed-upon deliverables prior to undertaking the work you could find yourself in an awkward situation later on. Similarly as a business you wouldn’t want your expensive contractor walking out after delivering half the work you thought was agreed upon.

It is likely a pre-work interview will take place so what sorts of information are you going to be looking for? Let’s start with high level questions:

  1. Why are you engaging us for this piece of work?
    • Issues with an existing deployment?
    • A new technology you want to make use of such as VoWiFi?

     

  2. Tell me about the company and stakeholders
    • Vertical type – Education, Health, Manufacturing
    • Who is funding this work e.g. CIO, CTO, Sales Dept, Branch office, Janitor etc
    • Any other major stakeholders

     

  3. Are you invested in a particular vendor?
    • Of course the only answer is Cisco*
    • Deployment type – Converged/Unified

     

  4. Detail the areas of the building you wish covered
    • Toilets
    • Lift shafts
    • Outdoor areas
    • Car Parks
    • Lunchrooms

Moving into lower level / more detailed questions:

  1. What types of application do you want to use on the wireless and are there are any specific requirements?
    • High / Med / Low bandwidth
    • Latency requirements e.g. no less than 100ms at all times including roaming
    • QoS requirements
    • Multicast requirements

     

  2. Explain your network requirements
    • Voice Network
    • Data Network – Internal Users
    • Guest Network – Visitors

     

  3. Discuss the devices in use for each network
    • Data – Domain machines only, BYOD Devices
    • Voice – 7925G phones
    • Guest – Any device that can login
    • Location – Asset tracking using passive/active RFID tags

     

  4. Is there a company security policy to adhere to?
    • User password policy
    • Encryption requirements
    • VLAN/Network separation
    • wIPS

     

  5. Will location services be required now or in the future
    • Which areas of the building will require location tracking – all/some
    • Passive / Active RFID tags in use?
    • Historical data requirements i.e. how long to retain the data

     

  6. Provide architectural plans of the building and discuss the building material types in use
    • Office dry walls
    • Metal lined rooms (X-Ray rooms)
    • Metal beams throughout buildings
    • Open area lobbies

     

  7. Provide details of the switch riser cabinet locations and the switch models in use
    • PoE capabilities e.g. 802.11af / 802.11at
    • Is there scope in the budget to replace these if required?

     

  8. Detail any areas requiring special access and arrangement of:
    • Access cards
    • Permission forms
    • Site inductions

     

  9. Discuss the SLAs in relation to these networks
    • High Availability requirements
    • Maintenance contract with vendor for support (TAC)

     

  10. Provide details on any branch offices and their variations (if any)
    1. Multi-country solution
    2. Different hardware in branches
    3. Traffic within a WAN
    4. Traffic split out through public Internet

 

*If Cisco ever has a question with “multi-vendor” solution as an available answer option, you can nearly always rule that answer out.

1.3.d Select an appropriate deployment model

This is where you take the information learnt through questionnaires and interviews to determine a proposed design. With Cisco’s current options this could be any of the following high level options:

  1. Unified Deployment
    • Autonomous
    • Autonomous – Workgroup Bridges
    • Lightweight Centralised
    • Lightweight Distributed
    • Mesh
    • FlexConnect Mode
    • Local Mode

     

  2. Converged Deployment
    • Mobility Controllers
    • Mobility Oracle
    • High Availability
    • Mesh

That is an extremely general list and it will be up to you to use your experience and knowledge to apply the appropriate solution you see fit to the customer requirements.

1.3.e Regulatory domains and country codes

RF requirements should be picked up through the questionnaire and business discussions. This will affect your proposed design as there are always country and industrial considerations to take into account. Understanding the ISM/UNII bands (below) and what channels you can use in your countries is pretty critical as each regulatory domain comes with its own caveats.

https://en.wikipedia.org/wiki/List_of_WLAN_channels

ISM – Industrial Scientific and Medical

902 – 928 MHz – (26MHz wide) – Industrial.
2.4 – 2.5 GHz – (100Mhz wide) – Scientific.
5.725 – 5.827 GHz – (150MHz wide) – Medical – Overlaps with UNII-3.

UNII Bands – Unlicensed National Information Infrastructure

23 Channels in total in 5GHz band.

4 Channels – UNII-1 – Lower – 100 MHz – 5.150 – 5.250 – FCC cap of 50MHz at IR – Indoor use.
4 Channels – UNII-2 – Middle – 100MHz – 5.250 – 5.350 – FCC cap of 250mh at IR. Indoor and Outdoor use.
4 Channels – UNII-3 – Upper – 100MHz – 5.725 – 5.825 – FCC cap of 1000mw – Mostly outdoor.
11 Channels – UNII-2 Extended – 255MHz – 5.470 – 5.725 – FCC cap of 250mw – Indoor / Outdoor – 802.11h.

Links

(2008) Cisco Site Survey FAQ

(2013) Site Survey and RF Design Validation – Voice Over Wireless LAN (VoWLAN) Troubleshooting Guide

(2013) Site Survey Guidelines for WLAN Deployment

 

 

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