Презентации / 1-2 Wireless Intro
.pdf
Avoid Mounting AP Antennas Too High
2.4 GHz
ØAs a general rule, antenna heights of 3 meters or less are most conducive to good coverage and consistent positioning accuracy when doing location.
ØAs a general rule, antenna heights of over 6 meters should be avoided.
ØIf required, then tricks exist, but you need to consult a specialist
ØIt is important to understand the requirement for external antennas in cases like this, as the cost of a deployment will become significantly higher.
How Does a Directional Antenna Radiate?
qAlthough you don’t get additional RF power with a directional antenna, it does concentrate the available energy into a given direction resulting in greater range, much like bringing a flashlight into focus.
qAlso a receive benefit - by listening in a given direction, this can limit the reception of unwanted signals (interference) from other directions for better performance.
A dipole called the “driven element” is placed in front of other elements.
This motivates the signal to go forward into a given direction for gain.
(Inside view of the Cisco AIR-ANT1949 - 13.5 dBi Yagi)
Wireless Deployment Modes
Deployment Mode: Autonomous
ØAP works as a standalone unit without interaction with or knowledge of other Aps
ØCisco is still investing in Autonomous Software (aIOS)
§15.2.x code supports: 1140,1250,1260, 3500, 1600, 2600, 3600, 1550
§Next release (15.2-4.Jx) aligned with 7.6 will support: AP700, AP1532, AP3700 (site survey mode only)
§AP 1532 comes with one SKU for Unified/Autonomous, use the command “AP#capwap ap autonomous” to convert it
ØBasic Services supported (Data and Voice). No RF visibility, limited scale, suited for < 4 sites
ØUsually APs are individually configured. Can use Cisco Network Assistant (CNA) to manage APs
§Easily discover APs in network. Network displayed visually in a topology map
§Bulk edit wizard configures common settings across multiple APs
§Configuration (AP Specific): SSID, VLAN, Channel Settings
§Free. Download it from www.cisco.com/go/can/
Deployment Mode: Controller based
Why do I need a Controller? And Why a Cisco one?
ØScalability
§Zero-touch configuration
§Centralized configuration management, image management and troubleshooting
ØRadio Frequency (RF) Management
§System wide view of RF – Cisco Only
§Dynamic Channel Selection, Dynamic Power Settings, Coverage Hole Detection/Mitigation (RRM)
§Advanced Interference Handling (CleanAir) – Cisco Only
ØAdvanced Mobility Services – Investment protection
§Advanced Location based Services (CMX) – Cisco Only
§Optimized end-end multicast delivery (VideoStream) – Cisco Only
§Advanced Wireless IPS (aWIPS)
§Advanced Roaming (802.11r)
Deployment Mode: Controller based
What Is CAPWAP?
qCAPWAP: Control and Provisioning of Wireless Access Points is used between APs and WLAN controller.
ØCAPWAP is an open protocol (IETF RFC)
ØControl Plane UDP 5246 (DTLS encrypted), Data plane UDP 5247 (optionally encrypted)
qAccess points discover and join a CAPWAP controller
qConfiguration and firmware can be pushed from the controller
qStatistics gathering and wireless security
Business
Application
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CAPWAP |
Data Plane |
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Controller |
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Wi-Fi Client
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Point |
Control Plane |
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Basic Functions of the WLAN Controller
qCentralized configuration and policy enforcement of the Wireless LAN
qAll access to network resources goes through the controller
ØRADIUS, DHCP, DNS, VLANs etc (assuming AP in Local Mode)
qController acts as security gateway for clients
ØAuthentication profiles, ACL enforcement, Bandwidth controls
qManages all access points on the network
ØAuto Channel and power assignments, coverage hole detection, firmware upgrade, statistics gathering, IDS & rogue AP Detection, RF analysis
qNo need to re-subnet the network for deployment (L2/L3 Roaming)
ØSimple plug and play deployment model, AP’s can be dropped into any local or remote network segment.
Campus Design: CUWN Centralized mode
Mobility
Group
WLC #1
Encrypted
(see Notes)
AP 
SSID – VLAN Mapping 
(at controller)
Intranet
WLC #2
CAPWAP
Tunnels
AP 
SSID2 SSID1 SSID3
Data Center / |
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Service block |
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Internet |
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Well-known, |
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proven |
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architecture |
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“Guest” Anchor WLC |
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Inter-Controller (Guest Anchor) |
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N D |
EoIP / CAPWAP Tunnel |
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Inter-Controller |
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EoIP / CAPWAP Tunnel |
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L E G |
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AP-Controller CAPWAP Tunnel |
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802.11 Control Session + Data Plane |
Notes –
•AP / WLC CAPWAP Tunnels are an IETF Standard
•UDP ports used –
•5246: Encrypted Control Traffic
•5247: Data Traffic (non-Encrypted or DTLS Encrypted (configurable)
•Inter-WLC Mobility Tunnels
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EoIP – IP Protocol 97 … AireOS 7.3 introduced CAPWAP option |
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Used for inter-WLC L3 Roaming and Guest Anchor |
FlexConnect overview
ØManagement and data plane are split
ØData Plane can be:
§Centralized (SSID traffic sent all to WLC)
§Local (SSID traffic sent all to local VLAN)
ØTwo modes of operation:
§Connected (when WLC is reachable)
§Standalone (when WLC is not reachable)
Central Site |
Cluster of |
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WLC |
Centralized
Traffic 
Centralized
Traffic
Ø Traffic Switching mode is configured per AP and per WLAN (SSID)
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From 7.3, split tunneling is supported on a per- |
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WLAN basis: the AP can NAT unicast IPv4 to local |
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hosts |
Local |
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Ø FlexConnect Group: |
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Traffic |
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§ |
Defines the Key caching domain for Fast L2 |
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Roaming, allows backup Radius scenarios and fast |
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code upgrade |
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mote Office with
FlexConnect