CCIE Enterprise Wireless (v1.0) – 3.7 Mesh – Part 2

Posted on Posted in CCIE Enterprise wireless, Mesh, MESH DFS RAP MAP

Part 1 covered the “basic” configuration required to to set up the mesh network. Part 2 will cover the details of the mesh network and the technologies used to communicate between the root access point (RAP) and the mesh access point (MAP).

One of the first things that I learned with mesh is that its a “coverage” technology and NOT a capacity technology. Mesh is generally used in areas where there is not an option to install new cable or in remote locations with limited infrastructure.

The RAPs will be installed in a central location, generally where this is existing network infrastructure. The RAP will join the controller via the wired network and will communicate with the MAPs its radio link.

MAPs DO NOT require a wired connection to the network. The MAP will join the controller via its radio link and will continue to communicate that way. One absolutely crucial component of the RAP is power, obviously without power the device cannot operate 🙂

Example of outdoor APs used for mesh.



Access Point Roles


Access points within a mesh network operate in one of the following two ways:
1 . Root access point (RAP)
2 . Mesh access point (MAP)

MAPs use the Cisco Adaptive Wireless Path Protocol (AWPP) to determine the best paththrough the other mesh access points to the controller. Bridge mode access points support CleanAir in mesh backhaul and provides only the interference device report (IDR) and Air Quality Index (AQI)reports.

Wireless mesh networks can simultaneously carry two different traffic types:


• Wireless LAN client traffic
• MAP Ethernet port traffic


Wireless LAN client traffic terminates on the controller, and the Ethernet traffic terminates on the Ethernet ports of the mesh access points.
Access to the wireless LAN mesh for mesh access points is managed by the following authentication methods:


MAC authentication—Mesh access points are added to a database that can be referenced to ensure they
are provided access to a given controller and mesh network.
External RADIUS Authentication—Mesh access points can be externally authorized using a RADIUS server such as Cisco ACS (4.1 and later) and ISE that supports the client authentication type of Extensible Authentication Protocol-FAST (EAP-FAST) with certificates and and WPA2/PSK on the WLCs.


Antennas

Overview
Antenna choice is a vital component of any wireless network deployment. There are two broad types of antennas:

Directional

Omnidirectional

Each type of antenna has a specific use and is most beneficial in specific types of deployments. Because antennas distribute RF signal in large lobed coverage areas determined by antenna design, successful coverage

An antenna gives a mesh access point three fundamental properties: gain, directivity, and polarization:

Gain—A measure of the increase in power. Gain is the amount of increase in energy that an antenna adds to an RF signal.

Directivity—The shape of the transmission pattern. If the gain of the antenna increases, the coverage area decreases. The coverage area or radiation pattern is measured in degrees. These angles are measured in degrees and are called beam-widths.

Polarization—The orientation of the electric field of the electromagnetic wave through space. Antennas can be polarized either horizontally or vertically, though other kinds of polarization are available. Both antennas in a link must have the same polarization to avoid an additional unwanted loss of signal. To improve the performance, an antenna can sometimes be rotated to alter polarization, which reduces interference.

A vertical polarization is preferable for sending RF waves down concrete canyons, and Polarization can also be harnessed to optimize for RF bleed-over when reducing RF energy to adjacent structures is important. Most omnidirectional antennas ship with vertical polarization as their default.


CAPWAP Discovery on a Mesh Network


The process for CAPWAP discovery on a mesh network is as follows:
1. A mesh access point establishes a link before starting CAPWAP discovery, whereas a non mesh access point starts CAPWAP discovery using a static IP for the mesh access point, if any.


2 . The mesh access point initiates CAPWAP discovery using a static IP for the mesh access point on the Layer 3 network or searches the network for its assigned primary, secondary, or tertiary controller. A
maximum of 10 attempts are made to connect.

3. If Step 2 fails after 10 attempts, the mesh access point falls back to DHCP and attempts to connect in 10 tries.


4. If both Steps 2 and 3 fail and there is no successful CAPWAP connection to a controller.


5. If there is no discovery after attempting Steps 2, 3, and 4, the mesh access point tries the next link.


Rebooted the RAP:


MAPs lost connection:








All of the MAPs will go through the same process until they find the RAP. The APs will then rejoin the controller. The RAP/MAP –> controller join process takes a while.


All of the access points rejoined the controller and show as UP on Cisco Prime:




verify / test client connectivity




client iperf test:




iperf traffic capture from client with MAC address – 00:20:a6:fc:b9:b7 to the iperf server


return traffic from the iperf server to the client with MAC address – 00:20:a6:fc:b9:b7


Force MAP0003 to go through MAP0004 to reach the RAP/controller.

Current state after changing the parent:




Mesh part 3

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.