Scalable voip mobility intedration and deployment- P23: The term voice mobility can mean a number of different things to different people. Two words that can be quite trendy by themselves, but stuck together as if forgotten at a bus station long past the last ride of the night, the phrase rings a number of different, and at times discordant, bells. | 220 Chapter 6 have gone through a planning process to determine how many calls can be safely allowed per access point while still leaving room for best effort data. That number is usually far lower than the best-case maximum capacity and is designed to be a low water mark barring external changes the network will be able to achieve that many calls most of the time. This number is then manually input into the wireless network which then counts the number of calls. If the maximum number of calls is reached on that access point the system will not let any more in. These static metrics may be entered either as the number of calls or a percentage of airtime. Systems that work as a percentage of airtime can sometimes take in a padding factor to allow for calls that are roaming into the network. Setting these values can be fraught with difficulty. Pick a number that s too low and airtime is being wasted. Pick a number that s too high however and sometimes call quality will suffer. Even percentage of airtime calculations are not very good because they may not take into account airtime that is unusable because of variable channel conditions or co-channel interference that the access point cannot directly see such as client-to-client interference see Sections and for some of these problems . All in all you might find vendors recommending setting the values to a low safe value that allows for voice to work even if there is plenty of variability in the network. This works well for networks that are predominantly data-oriented but voice-only networks cannot usually afford that luxury. Load Balancing Load balancing is the ability for the network to steer or direct clients towards more lightly loaded access points and away from more heavily loaded ones. As you may recall from the discussion in Section for scanning and will see in the discussions in Section the client decides to which access point the client will connect. However the network has the .
