选择Trapeze的八个理由.ppt

* * * * * * Let’s look at voice. So what’s the problem with voice in a centralized architecture? Well, all the traffic goes through the central controller. This increases latency, and yields an architecture that’s not very flexible for dealing with voice. Voice is inherently a peer-to-peer application. The way SIP or the way VoIP works, a handset talks directly to another handset when a call is established. Or a handset talks directly to a PBX if it’s trying to interconnect to the PSTN. Voice is inherently an application that requires low latency. So it’s highly desirable to take the shortest possible path through the network and touch the minimum number of devices that you need to touch. But a centralized architecture touches a whole lot of boxes it doesn’t need to touch because it forwards everything through a centralized wireless LAN switch. Many times, that switch is not very close to those APs. For example, in a campus network, with switches in one building and APs throughout three buildings on campus, traffic could be coming all the way across campus, back into the central building, back across, and back to the building where the call started. Sometimes they’re hosted across wide area links. And if there’s high latency just in the wired infrastructure between the boxes, that adds to the problem. So how does Smart Mobile deal with voice? Well, Smart Mobile says, “This is a peer-to-peer application. It needs low latency. Let’s push all of the traffic forwarding to the access point.” In this way, traffic flows across the core network once, takes the shortest possible path through that network, takes the lowest possible latency path through that network. It’s an architecture that looks exactly like SIP. So you could replace that WLAN controller with a box that says SIP gateway. And the picture would look the same. Because the control and management traffic for a SIP handset would go to the SIP gateway. But the calls would go handset to hand