CWNA

CWNA Summary Notes: Legacy 802.11 Security | Legacy Authentication

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Legacy Authentication

Legacy authentication methods were more of an authentication of capability (verification between two devices that they were valid 802.11 devices) and not so much an authentication of user identity.

They are of two types: Read the rest of this entry »

CWNA Summary Notes: 802.11 Network Security Architecture

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Components of a Secure Network

Required components when securing a network are:

Data Privacy and Integrity

Access to Wireless medium is unrestricted hence the use of cipher encryption technologies is needed for proper data privacy.

A cipher is an algorithm that is used to perform encryption:

  • RC4 algorithm ( Ron’s Code / Rivest Cipher)
    • It encrypts data in a continuous stream (streaming cipher)
    • Used in technologies used to protect Internet traffic eg SSL (Secure Socket Layer)
    • Incorporated into 2 legacy encryption methods: WEP and TKIP
  • Advanced Encryption Standard Algorithm (AES) / Rijndael Algorithm
    • Encrypts data in fixed blocks
    • Much stronger than RC4
    • Uses Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP) encryption method
    • Encryption key strength options are 128, 192 or 256 bits.

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CCNP Wireless CUWSS 642-732 Summary Notes 24 : Installation Report

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Post Deployment

A detailed hardware requirement list should have:

Wireless equipment needed

Supporting infrastructure upgrades

  • RF Validation for the installed wireless network
    • Co channel interference and appropriate channel separation
    • Power levels are consistent with site survey
    • If designing for AP failover or designing to RRM
    • RF Coverage (band by band)
  • Roaming audit
    • Airmagnet can be used in active and also using IPERF
  • Wireless Infrastructure
    • If designing especially globally, verify channel allocation is consistent
    • For 5 GHz band, make sure that the clients support all those UNI bands.Verify that RRM is consistent with what was achieved during survey
  • Application testing
    • Validate all layers 1 through 7

Installation Report / Deliverables

This report describes the deployment methodology and the tests that were performed to validate the installation.

The report should include the following:

  • Spectrum analysis
  • RF coverage analysis
  • Hardware placement and configuration
  • Application analysis – Includes results from application throughput testing

Read the rest of this entry »

CCNP Wireless CUWSS 642-732 Summary Notes 8 : Bridging Models

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 Point to Point Wireless Links

Cisco Aironet 1500 Series Access Point can use its backhaul radio to bridge two wired segments in point to point mode. Its a mesh network with only one MAP and no WLAN clients. If Ethernet bridging is enabled, then wireless client access can be provided but is not recommended if the MAP is too high on the rooftop. Read the rest of this entry »

CCNP Wireless CUWSS 642-732 Summary Notes 3 : RF Applications and Client Devices

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RF Applications

Data rate is just the link speed and not the throughput (download speed).

  • 802.11b at an 11-Mbps data rate offers on average a 5.5-Mbps throughput. 11b usually degrades performance for other devices in the other bands. Avoid using this band, unless you have old devices.

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CCNP Wireless CUWSS 642-732 Summary Notes 2 : Site Survey Preassessment

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Site Survey Pre-assessment can be done using a questionnaire that should have most of this information to enable proper design planning for the WLAN.

  • Customer contact information
  • Total number of sites
  • Is it a New vs existing deployment
  • Band requirements
  • Existing devices
  • Data coverage type (VoWLAN, Data, Location services)
  • Facility information – get maps for those areas
    • Ceiling heights
    • Racking or shelving?
    • clearance above storage level
    • any hazardous areas
    • special safety requirements like safety glasses.
  • Number of buildings per site
  • Hours of operation
  • Current network infrastructure.
    • Confirm the port capacity.
    • Network topology
    • Media type
    • Confirm power for APs
      • Most are capable of being powered with 802.11af
      • Cisco AP 1250 requires 18.5 power for full power
  •  RF Coverage information:
    • RF coverage inside and outside
    • Complete or selective RF coverage
    • Encryption to be utilized
    • Utilizing rate shifting

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CCNP Wireless CUWSS 642-732 Summary Notes 1 : Site Survey Requirements for Different Vertical Industries

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A site survey is a task-by-task process in which the surveyor studies the facility to understand the RF behavior, discovers RF coverage areas, checks for RF interference, and determines the appropriate placement of wireless devices.

Top considerations:

  • Identify Customer Requirements  and his expectations. What type of environment?
  • Consider the regulatory issues for that particular site
  • Asses the network before deployment
  • Consider logistics.
  • Consider the models that we will use on the site Read the rest of this entry »

CWNA Summary Notes: Coverage Analysis Methods

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Manual Site Survey

Passive manual survey – The radio card collects RF measurements but the client adapter is not associated to the access point during the survey, and all information is received from radio signals that exist at layer 1.

Active manual survey – the radio card is associated to the access point and has layer 2 connectively, allowing for low-level frame transmissions. If layer 3 connectivity is also established, ping traffic is sent in 802.11 data frame transmissions. RF measurements, packet loss and re-transmission percentage recorded.

Moth types of survey are recommended. Read the rest of this entry »

CWNA Summary Notes: Site Survey Tools

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Indoor Site Surveys Tools

  1. Spectrum analyzer for RF spectrum analysis
  2. Blueprints or floor plans of the facility
  3. Received signal strength measurement tool
  4. 802.11 client card – prefer the vendor that will be deployed
  5. AP – preferably 2.
  6. Battery pack for AP and for the laptop
  7. Binoculars to view distant objects ( eg high ceiling and in the ceiling)
  8. Walkie-talkies or cellular phones for communication with site survey partners etc
  9. Antennas, both omni-directional and indoor semi-directional
  10. Temporary mounting gear – Bungee cords, plastic ties, duct tape, tripod
  11. Digital camera to record the exact placement of the APs and site specific information
  12. Measuring wheel (best p[tion) or laser measuring meter to measure cable distances
  13. Colored electrical tape to mark where AP was mounted. Advisable to use different colours for different channels.
  14. Ladder or forklift to mount the APs

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CWNA Summary Notes: Spectrum and Coverage Analysis

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Spectrum Analysis

A noisy environment can cause the data in 802.11 transmissions to become corrupted -> the cyclic redundancy check (CRC) will fail -> the receiving 802.11 radio will not send an ACK frame to the transmitting 802.11 radio -> the unicast frame is not acknowledged
and will have to be re-transmitted. Wi-Fi data networks can handle a retransmission rate of up to 10 percent, but a Voice over Wi-Fi (VoWiFi) network needs to limit packet loss to a rate of 2 percent or less. Read the rest of this entry »

CWNA Summary Notes: Capacity and Coverage Requirements

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Capacity and Coverage Requirements

Factors that should be considered when planning for Capacity:

  • Data applications.
    • For 802.11b/g network, 12 to 15 data users per AP
    • ForVoWiFi
      • SpectraLink recommends max of 12 calls per 11 Mbps cell (with 1 call needing 4.5 % of AP bandwidth), 7 calls per 2 Mbps (with 1 call needing 12% of AP bandwidth). This can be predicted using the Erlang Formula. Erlang – one hour of telephone traffic in one hour of time.
  • User density. A high concentration of human bodies can attenuate the RF signal due to absorbtion.Consider:
    • How many users currently need wireless access
    • How many users many need connectivity in the future
    • Where are the users
  • Peak on/off use
  • Existing transmitters
    • Previously installed 802.11 network
    • Interfering devices
      • microwaves
      • cordless headsets
      • cordless phones
      • wireless machinery
  • Mobile vs Mobility
    • When one is mobile – disconnect may be ok (moving with the laptop from one desk to another). roaming may not be a requirement.
    • For mobility – user must be connected 100% of the time when travelling through the facility eg
      • VoWiFi
      • Warehouse scanning applications
  • 802.11g protection mechanism. This will always affect throughput due to backward compatibility with 802.11b HR-DSSS clients that support a max data raet e of 11 Mbps as compared to 54 Mbps for the 11g clients.

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CWNA Summary Notes: Procedures for Performing a Site Survey

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Gather background data for the site survey

Examine business requirements

  • Why do they need a WLAN
  • is mobility required
  • What devices will be connecting
  • What apps will be used
  • What is the amount of bandwidth required by the user

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CWNA Summary Notes: Specialized Site Survey Tools

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These tools include:

  • dedicated site survey applications
  • spectrum analyzers
  • protocol analyzers
  • documentation tools
  • Voice over WiFi (VoWiFi) Tools and Surveys

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CWNA Summary Notes: What is a Site Survey

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A Site Survey is an in-depth examination and analysis of a WLAN site.

Purpose of a Site Survey

  • Achieve the best possible performance from the WLAN
  • Certify that the installation will operate as promised
  • Determine the best location for APs
  • Develop networks optimized for a variety of applications
  • Ensure that the coverage will fulfill the organization’s requirements
  • Locate any unauthorized APs on the network
  • Map any nearby wireless networks to determine existing radio interference
  • Reduce radio interference as much as possible
  • Make the wireless network secure

Read the rest of this entry »