Cisco Cisco MGX-FRSM-HS2 B Serial Frame Service Module 技術マニュアル
Basic Radar Survey for Wireless Mesh Networks
Document ID: 91565
Contents
Introduction
Prerequisites
Requirements
Components Used
Conventions
Basic Radar Survey
Additional Information
Starting Points
Topology
Selecting a Good Location for the Survey
Selecting the Detecting Equipment
Initial Setup
Radar Tests using 4.1.192.17M
Radar Tests using 4.0.217.200
Radar Events Count in AP
Radar Affected Channels in AP 1520
Using Cognio Spectrum Analyzer
Steps to Take if a Radar is Detected
Related Information
Prerequisites
Requirements
Components Used
Conventions
Basic Radar Survey
Additional Information
Starting Points
Topology
Selecting a Good Location for the Survey
Selecting the Detecting Equipment
Initial Setup
Radar Tests using 4.1.192.17M
Radar Tests using 4.0.217.200
Radar Events Count in AP
Radar Affected Channels in AP 1520
Using Cognio Spectrum Analyzer
Steps to Take if a Radar is Detected
Related Information
Introduction
This document offers two methods to scan for radar signals across 802.11a outdoor channels before
deployment of mesh networks. One based on 4.0.217.200 image, the other using newer functionality on the
mesh released, in particular 4.1.192.17M. It covers both 1520 and 1510 mesh access point families.
deployment of mesh networks. One based on 4.0.217.200 image, the other using newer functionality on the
mesh released, in particular 4.1.192.17M. It covers both 1520 and 1510 mesh access point families.
The objective is to provide a mechanism to check for possible radar signals that can affect a wireless mesh
network that uses 802.11a as backhaul links.
network that uses 802.11a as backhaul links.
It is important to validate the presence of radar on any wireless mesh deployment. If during operation, an
access point (AP) detects a radar event over the Radio Frequency (RF) channel that the network backhaul
uses, it must immediately change to another available RF channel. This is dictated by Federal
Communications Commission (FCC) and European Telecommunications Standards Institute (ETSI)
standards, and is established to allow the sharing of the 5 GHz spectrum between wireless LAN (WLAN) and
military or weather radars that use the same frequencies.
access point (AP) detects a radar event over the Radio Frequency (RF) channel that the network backhaul
uses, it must immediately change to another available RF channel. This is dictated by Federal
Communications Commission (FCC) and European Telecommunications Standards Institute (ETSI)
standards, and is established to allow the sharing of the 5 GHz spectrum between wireless LAN (WLAN) and
military or weather radars that use the same frequencies.
The effects of radar signal over a wireless mesh network with 802.11a backhaul can be different. This
depends on where the radar is detected and on the state of full sector DFS mode configuration setting (in
case it is disabled):
depends on where the radar is detected and on the state of full sector DFS mode configuration setting (in
case it is disabled):
If a mesh access point (MAP) sees the radar on the current channel, it goes silent for one minute
[dynamic frequency selection (DFS) timer]. Then, the MAP starts to scan channels for a suitable new
parent to associate again to the mesh network. The previous channel is marked as not usable for 30
minutes. If the parent [other MAP or rooftop access point (RAP)] does not detect the radar, it remains
on the channel and is not visible for the MAP that did detect it. This situation can occur if the
detecting MAP is closer or in line of sight of the radar, and the other APs are not. If no other parent is
available in another channel (no redundancy), the MAP remains off network for the 30 minutes of the
[dynamic frequency selection (DFS) timer]. Then, the MAP starts to scan channels for a suitable new
parent to associate again to the mesh network. The previous channel is marked as not usable for 30
minutes. If the parent [other MAP or rooftop access point (RAP)] does not detect the radar, it remains
on the channel and is not visible for the MAP that did detect it. This situation can occur if the
detecting MAP is closer or in line of sight of the radar, and the other APs are not. If no other parent is
available in another channel (no redundancy), the MAP remains off network for the 30 minutes of the
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