This is the landing page for all the wireless related posts on my blog. Majority of the content is towards my study for wireless related certifications like CWNP. The name ‘It Depends!’ is given as it is the majority of the answers or responses to the wireless queries
This blogpost focuses on using ExtremeCloudIQ from Extreme Networks. The portal is quite a user friendly and has some built-in capabilities which can help troubleshoot day to day problems with Wireless. Let's take a look.
The good thing about Extreme Cloud IQ is you can see Real-Time & Historical client information of their connections. This does help to find out which AP was/is the client associated with, the SNR and check other stats like roaming, DHCP, DNS. You can navigate to this by clicking on Manage > Clients
You can drill down by searching for the client using IP Address / Mac Address / Device Host Name
After clicking on the client you can see the current connection status on the right hand side with regards to VLAN/SSID/Radio/Channel. On the Top you can check the current AP associated. The page has lot of details about the client and more information can be drilled by changing the Time Range to Day/Week/Month depending on how far you want to analyse.
You can further scroll down to check the roaming patterns/time for the client and also check what apps it is using. I've found the Session Details section quite useful to check WiFi Health, Application Health and Client Radio Info etc.
From this screen one can navigate to CLIENT TOOLS which has an option for "Troubleshoot Now" which runs the client monitor and captures the events as they happen.
You can perform device level checks by Navigating to Manage > Devices - page. The list can be filtered based on the Locations/Device Types/Connection state/SSID etc..
You can run command line from this screen targeting to one/multiple devices to show relevant information like below.
Action > Advanced > CLI Access
There are lot of tools available on the portal which can help with the Wi-Fi analysis. This section can be navigated via Manage > Tools section
The Client Monitor is a good place to start looking at the network-wide issues for any Association/Authentication or Networking (DHCP/DNS) issues.
Packet Capture - Can easily perform AP radio interface level capture for analysis or requested by TAC for troubleshooting.
The Utilities tab opens up a whole lot of useful features. I've found a few ones to be really helpful.
- Locked Devices - Can be used to unlock devices that are locked due to failed authentication when using PPSK.
- Get Tech Data - instantaneously captures the Tech Data from AP, similar to the "show tech support" command. Useful to avoid sometimes having to scroll annoyingly for mins to capture the information.
- VLAN Probe - Useful to check the number of available IP addresses on a VLAN.
- Device Diagnostics - The section can open a range of commands which can be executed per/AP level to extract relevant information.
The Diagnosis tab show the captures executed on the devices and display their log information.
One of the key things to note from Aerohive/Extreme documentation that they provide good contextual info when navigating in a particular section or screen.
Examples like below
This blogpost is dedicated to provide feedback for the CWISA-101 used to be known as CWSA before.
Let's begin by looking at the objectives of the exam.
Surely you'd see that there is some overlap of the topics such as Radio Frequency Planning, Wireless Technologies and Implementing Wireless Solutions with CWNA exam. If you are like one of me who have completed the CWNA and other CWNP (CWSP, CWAP and CWDP) exam this exam will be a lot easier. Having said that there were some topics completely new to me around the IoT, Cellular Networks, LoRaWAN technologies. There is some content around Programming and Scripting but only covers basics and an overview of API.
For someone who has not completed any CWNP exams and then preparing for this one, it may be a bit overwhelming. The exam dedicated 30% of its content to Planning Wireless Solutions which encompasses around 18 questions. You can visit this link for a detailed description of the exam requirements.
Resources for the exam
- CWISA (1/2) Practice Tests
- Be sure to get hold of the official study guide - Be sure to read the book and go through the exam tips carefully. The book is available in Kindle/Hardcopy at the moment.
- Cisco Live Presentation for IoT
The exam is now a requirement to fulfil the requirements to be CWNE, so if your aim is to achieve that title you are just one step closer to it.
Also, you can choose any professional level exam (Connectivity, Integration) to do next.
Also, there are new exams in pipeline going to be announced soon.
CWIDP – Certified Wireless IoT Design Professional
CWISE – Certified Wireless IoT Solutions Expert
One of the shortest blogpost but lot can go on if you think about IoT.
Applying Wireless Design Requirements
- Defining AP coverage - The main goal of the Wi-Fi design to bring the network to the users.
- Considering Receive Sensitivity - AP Tx power is a major factor in determining the usable range of its signal. Every client device has a receiver that has a sensitivity level or threshold that divides the intelligible, useful signals from unintelligible devices.
- A commonly used cell boundary is 67dBm
- Considering SNR = SNR must be greater than the noise floor by a decent amount so that it can be received and interpreted correctly.
- SNR also determines the cell boundary.
- Further AP cell considerations
- DRS (Dynamic Rate Shifting) - Clients/AP can lower the data rate when data is not acknowledged at the same rate it was sent.
- DTPC - Dynamic Transmit Power Control is a Cisco Proprietary method that AP use to advertise their own tx power so that compatible clients can adjust their tx power levels accordingly. Clients must support Cisco Compatible Extensions (CCX) for participating in this. Cisco recommends DTPC to be turned ON, by default it is ON.
- Expanding coverage with additional AP - Need Tx power adjustments if capacity requirements need to be met for a design - Repeat channel layout can be used to work with co-channel interference issues.
- Designing a Wireless Network for Data
- Disable low data rates if legacy devices are not used.
- Clients will try to use higher rates if RF conditions support it.
- Even though disabling lower data rates does reduce the usable cell size, the cell boundary will not move enough to interfere with the design constraints.
- Designing a Wireless Network for High Density
- Distribute users multiple AP and channels.
- AP cell size needs to be reduced to cater to more users. This can be done by adjusting the Tx power and using an appropriate antenna for the AP.
- Leverage DTPC to automatically influence the tx power.
- Use DFS channels to leverage the 5GHz band in dense environments.
- Use FRA (Flexible Radio Assignment) - aka software-defined radios in AP running dual radios to switch 2.4GHz channel to 5GHz when sensing more 5GHz client density.
- Designing a Wireless Network for Voice/Video
- Need to carefully use DRS (Dynamic Rate Shifting) to mitigate user disruptions
- Follow appropriate QoS consideration to mark and prioritise user traffic.
- Use 802.11r, k and v that streamline roaming and authentication.
- Consider using DFS only is radar activity is not detected in the location.
- Designing a Wireless Network for Location
- RTLS can be used to track assets, rogue devices, also to location wireless clients within a building or a campus.
- AP should be positioned such that multiple AP can receive a signal from a device to be located, a minimum of 3 AP should be able to receive a client's signal while four or more AP are preferred.
- The derive a fairly accurate location, multiple AP must receive the client device or tag at RSSI above -75dBm.
- In a multi-floor building, AP should be staggered and not kept in straight lines.
Physical and Logical Requirements
- Physical Infrastructure Requirements
- POE and POE+
- POE is widely used technology that provides power to the AP over a twisted pair of Ethernet cable.
- PSE is mostly a POE injector or POE capable switch
- PDs (powered device) - Access Points, POS machines etc.
- IEEE 802.3af (POE) 15.4W PSE 12.95W PD IEEE 802.3at (POE+) 25.5W PSE 30W PD
- UPOE and UPOE+
- Cisco has developed extended POE capabilities
- Universal POE is capable of delivering 60W per port and UPOE+ up to 90W
- UPOE and UPOE+ are Cisco proprietary
- In 2018, IEEE standard 803.3bt as a standard to deliver up to 90W sometimes referred to as POE++
- MultiGigabit - Cisco AP can deliver speeds of 2.5Gbps, 5/10Gbps on existing cables. Cisco 3800/4800 and Catalyst 9100 AP support mGig technology.
- Ceiling and Mounting AP - Above/Below ceiling brackets.
- Grounding and securing AP - not always required for indoor AP, may be required to external AP requiring earthing/grounding connections.
- POE and POE+
- Logical Infrastructure Requirements
- CAPWAP flow
- CAPWAP Control Channel - uses UDP port 5246
- CAPWAP Data Channel -uses UDP port 5247
- AAA and DHCP services logical path
- CAPWAP uses controllers management interface t o communicate with AAA servers as well as other services.
- Licensing Overview
- Permanent Licenses
- Adding AP count licenses
- Evaluation Licenses
- Smart Licensing - uses centralised pool to license AP as and when required.
- Catalyst 9800 controllers require mandatory smart licensing
- CAPWAP flow
Conducting an Offsite & Onsite Site Survey
- AP radio signals are expressed in dBm.
- Common obstacles
- Note that the above is for general reference only, they can change depending on the area/country requirements.
- Common deployment models.
- Enterprise office
- Increase in devices
- Increase in mobility needs
- Roaming requirements
- Voice/Video/Location analytics
- Environments with X-ray/Imaging/Lab areas.
- Legacy or older devices.
- Interference expected from lab equipment like ECG etc.
- Aesthetics requirements
- Hospitality and Hotels
- Dense environments
- Captive portal/guest handling
- Aesthetic requirements
- Dense environments
- BYOD device catering
- Legacy devices
- Neighbouring location wifi interferences
- PCI specific regulations
- Directional antenna due to shelving
- Secure AP in enclosures depending on the environment
- Enterprise office
- Design with regulations in mind
- EIRP = Tx Power (dBm) + antenna gain (dBi) - cable loss (dB)
- FCC Regulations
|2.4GHz (FCC)||36 dBm (4W) EIRP (P2MP), with 30 dBm (1 W) Tx / 6 dBi, 1:1 ratio. 36 dBm (4 W) EIRP (P2P) with 30 dBm (1 W) Tx / 6 dBi, 3:1 ratio.|
|U-NII-1 (FCC)||Outdoors: Max EIRP 36 dBm (4 W). Indoors: Max Tx 17 dBm (50 mW), 6 dBi.|
|U-NII-2A (FCC)||Max EIRP 30 dBm (1 W), max Tx 24 dBm ( 250 mW).|
|U-NII-2B (FCC)||Not allowed for unlicensed use.|
|U-NII-2C (FCC)||Max EIRP 30 dBm (1 W), max Tx 24 dBm (250 mW). DFS required.|
|U-NII-3 (FCC)||Max EIRP 30 dBm (1 W), max Tx 24 dBm ( 250 mW).|
|2.4GHz (ETSI)||Max EIRP 20 dBm (100 mW), max Tx 17 dBm ( 50 mW) on 3 dBi. 1:1 rule.|
|Band 1 (ETSI), Sub-band 1 (U-NII-1)||Max EIRP 23 dBm (200 mW).|
|Band 1 (ETSI), Sub-band 2 (U-NII-2A)||Max EIRP 23 dBm (200 mW) with TPC. Max EIRP 20 dBm, (100 mW) without TPC. DFS required.|
|Band 2 (ETSI) (U-NII-2C)||Max EIRP 30 dBm (1 W) with DFS and TPC. Max EIRP 27 dBm (500 mW) with DFS and no TPC. Max EIRP 20 dBm (100 mW) without TPC and DFS.|
|Band 3 (ETSI) (U-NII-3)||Under discussion. Not allowed for Wi-Fi yet. Target 14 dBm (25 mW).|
- Conducting an Offsite Site Survey (Predictive Design)
- Choosing the Right survey
- Blueprint study
- Predictive survey
- Multiple types of onsite survey
- Layer 1 site survey
- Layer 2 site survey
- Post-deployment site survey
This blogpost will focus on the configuration of QoS policies on Extreme Cloud IQ (Portal). Aiming to provide a real scenario which led to the implementation of QoS for an organisation. Before diving into this I cannot stress on the point that QoS solution will be successful only if it is implemented end to end. The QoS marking and policing if not honoured by the subsequent hops in the access <> distribution <> core.
The Need for QoS
The issues arise when packets do not get prioritisation and are either dropped or queued. The network transmission quality is determined by latency, jitter and packet loss. It becomes even more crucial with Wi-Fi being a shared and half-duplex medium it becomes all the more necessary to mark and prioritise the relevant traffic on the network. One may have 10Gbps internet or more but AP are often the bottlenecks in the network. With the adaptation of VoIP/Skype/Zoom and similar RTP/SIP applications, there is a need to make sure voice/video traffic get priority over other traffic. Moreover, Wireless networks and protocols are mostly designed for data services... so it is normally not possible “ just to drop” Rich Media on top and expect positive results.
Extreme Cloud IQ configuration
Let's start with looking at the Extreme Cloud IQ configuration.
QoS Classifier Maps > Classifier map is used to mark traffic with Extreme Network QoS classes by various QoS classification systems (802.1p/DiffServ/802.11e).
Incoming Traffic - AP prioritises and forwards the incoming traffic as determined by the mapped QoS level.
Outgoing Traffic - AP uses marker maps.
If you login and navigate to below for checking the first option of "Classifier Maps".
Configure > Network Policies > Edit "Policy Name" > Additional Settings > QoS Options
The incoming traffic is mapped based on the network/application service defined in the classifier map. In the above screenshot you can see LYNC, LYNC AUDIO and others set as VOICE and action being PERMIT.
MAC OUIs and SSIDs
I haven't used this in our config but one can choose to map traffic to classes based on either the source/destination MAC OUI in the packet or based on SSID
802.1p is a layer 2 prioritisation often described as Class of Service can be seen in the TCI field of the Ethernet frame. The 3 bits give 8 different classes as shown below. In my scenario I have used the DiffServ and 802.11e(WMM) for layer 3 QoS.
DiffServ is concerned with classifying packets as they enter the local network. This classification then applies to Flow of traffic where a Flow is defined by 5 elements; Source IP address, Destination IP, Source port, Destination port and the transport protocol. The DSCP QoS is retained end to end and one of the reason it is preferred more than 802.1p.
Before moving to 802.11e, let's get basics correct.
802.11 use collision avoidance mechanisms unlike collision detection for Ethernet. The DCF (Distributed Coordinated Function) algorithm is used for media access. Regardless of any clients on the medium, a 802.11 WLAN device will wait for a DCF interframe space and then begin the transmission. Once the DIFS is counted down to 0, a random backoff timer is generated if the medium is not free.
QoS is not possible with DCF alone and hence 802.11e was ratified. The EDCA (Enhanced Distributed Channel Access) included 4 queues(Background, Best Effort, Video, Voice), AIFS (ACs) and a range of contention windows (CWmin and CWmax). Two additional 802.11e enhancements included TxOP and Call Admission Control (CAC)
For outgoing traffic, one can define marker maps to map classes to priority numbers in standard classification systems (802.11e, 802.1p, and DiffServ). After defining classifier and marker maps, you then define classifier and marker profiles that enable one or more of the methods defined in the maps. Finally, you associate those profiles with SSIDs or interfaces to apply the mappings to traffic arriving at or exiting those interfaces.
Verifying if WMM QoS is working
The QoS Data Frame includes the QoS Control field which provides the information in the Priority field.
Adding Custom Application for QoS Categorisation
Navigated to > Configure > Application > Add Custom
Helpful links for more readingRead more link text