WiNG5_VoWLAN_Best_Practices by Advantec Distribution

VoWLAN Best Practices WiNG 5

Vik Evans Systems Engineer Enterprise Networking and Communications

VoWLAN Best Practices: Topics

 Planning  Design  Implementation  Configuration

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 3

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 4

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?

VoWLAN Best Practices: Topics

 Planning  Design  Implementation Configuration

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 7

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 8

Design (cont.)

 Site Survey highly recommended  Spectrum analysis minimum

Use for reference of existing environment.  May be revisited postimplementation to verify install

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. 10

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 11

VoWLAN Best Practices: Topics

 Planning  Design  Implementation Configuration

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 13

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

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 15

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

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

Conclusion

 For more resources on WiNG 5 configuration for voice, see the EWLAN Sales Enablement Pages:  http://compass.motsolutions.com/web/wlan/Guides  http://compass.motsolutions.com/web/wlan/How To Videos