VoWLAN Best Practices WiNG 5 Vik Evans Systems Engineer Enterprise Networking and Communications 1
VoWLAN Best Practices: Topics Planning Design Implementation Configuration 2
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? 5
VoWLAN Best Practices: Topics Planning Design Implementation Configuration 6
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 1 st 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 9
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 12
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 14
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 16
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 17
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 18