wing5_vowlan_best_practices
Post on 28-Mar-2016
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11
VoWLAN Best Practices
Vik Evans
Systems Engineer
Enterprise Networking and Communications
WiNG 5
22
VoWLAN Best Practices: Topics
Planning
Design
Implementation
Configuration
33
Planning
Starts with project information gathering
Determine client info
Manufacturer(s) / Model(s)
Specs (Tx pwr, receive sensitivity, protocols)
# of clients to support
Manufacturers recommendations
Device Certifications & latest drivers
Applications to support on network
Understand possible segmentation
Understand voice requirements (capacity)
Push-to-talk? Broadcast / multicast concerns
44
Planning (cont.)
Know the wired infrastructure - audit
What data switches
Port densities for AP’s
PoE or no PoE – if so, which standard
Uplink capacity – 1Gbps, LAG
Identify for design phase
Logical Landscape
Flat or Tiered network & what changes may be needed
Existing IP scope – room for growth
VLAN existence / structure
55
Planning (cont.)
QoS Planning
Is there any prioritization currently?
Will there be any traffic tunneling?
If so, what IP header markings will be needed?
Note boundaries (firewall / router)
Will ACL Priority marking be necessary?
66
VoWLAN Best Practices: Topics
Planning
Design
Implementation
Configuration
77
Design
Starts with logical integration
How will wired network accommodate WLAN
Plan Application separation (VLAN’s)
Plan service level enforcement (QoS)
802.11e / WMM (L2) / DSCP (L3) - prioritization
WLAN and LAN
Physical integration
Resilience planning
LAN uplinks
WLAN core (controller redundancy)
Cell / neighbor coverage
88
Design (cont.)
For multi-site, individually large installs, interviews are a huge help.
Site IT contact
Example: Individual schools for entire district
Predictive Modeling
1st recommendation; minimum
Garbage in / garbage out –modeling elements are extremely important
99
Design (cont.)
Site Survey highlyrecommended
Spectrum analysis minimum
Use for reference of existing environment.
May be revisited post-implementation to verify install
1010
Design (cont.)
Voice concerns
Capacity planning
What 802.11 protocols will be used (b only / g / a)
What voice codecs? Will contribute to per-call BW
Expected number of simultaneous calls
Push-to-talk? - multicast
Wireless concerns
Coverage is a combination of cell boundaries and channel overlap
“% of overlap” – what does this mean? Not a good guideline.
1111
Design (cont.)
Wireless concerns (cont.)
Use min/avg RSSI values for coverage
Channel capacity as metric, not AP capacity
Co-channel interference affects channel capacity
Expected number of simultaneous calls
AP power – plan cell coverage that doesn’t support lower data rates; meaning higher density
To avoid power-asymmetry, AP power should be comparable to client device Tx power
Industry rule is -65 to -67 dBm to maximize throughput and minimize co-channel
Utilize Smart-RF for fine-tuning; establish base parameters.
AP Choice – is support for legacy protocols necessary
1212
VoWLAN Best Practices: Topics
Planning
Design
Implementation
Configuration
1313
Implement / Configure
Traffic segmentation - VLANs
Segment voice clients from other traffic
IP address space conservation
Voice client protection
Simplifies QoS configuration & troubleshooting
Segmentation required on wired as well as wireless
Data VLAN(s)
Voice VLAN
Voice WLANs mapped here
Other
1414
Implement / Configure (cont.)
Wireless Voice general rules
-65 to -67 dBm avg RSSI
5.5mbps min. data rate
AP power: start at 17dB; likely to work down
5GHz operation for voice clients preferred
More channels = higher capacity
Consider UNII-1 & 3 only – no requirement for DFS / TPC
1515
Implement / Configure (cont.)
Utilize QoS mechanisms of WiNG 5
Radio QoS Policies – QoS on AP radios
Admission Control
QoS has little effect when AP’s are over-subscribed
Use AP profiles to set per radio MU limits
WLAN QoS Policies – QoS on WLAN
Create separate WLAN’s for data and voice hosts
Enable QoS on wired Network
QoS needs to be implemented on network, end-to-end
DiffServ / IP TOS (L3), Queuing methods - wired
1616
Implement / Configure (cont.)
Client Considerations
Push-to-Talk clients
Can IGMP Snooping be used?
Will lower overhead for broadcast traffic, sending only to AP’s with registered clients
May further segment PTT from other voice clients at WLAN
Legacy clients
May not support WMM; segment from newer client devices
1717
Implement / Configure (cont.)
Verify post-install with a site survey
Include stairwells, cafeterias, etc.
Do not limit survey to purpose-built app. Use same network applications that users will
1818
Conclusion
For more resources on WiNG 5 configuration for voice, see the EWLAN Sales Enablement Pages:
http://compass.mot-solutions.com/web/wlan/Guides
http://compass.mot-solutions.com/web/wlan/How To Videos
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