There's no CDMA on a switched network...
Hamish On 28/04/14 19:29, Frank O'Connor wrote: > Sorry, > > I meant CDMA ... collision detection. Error correction, as Hamish said > ... is a level 3 Feature. > > Again ... just my 2 cents worth ... > --- > On 28 Apr 2014, at 6:39 pm, Hamish Moffatt <[email protected] > <mailto:[email protected]>> wrote: > >> On 28/04/14 18:22, Frank O'Connor wrote: >>> Well, yeah ... but: >>> >>> 1. ANY form of networking causes 'slow-downs' simply by its very >>> nature, irrespective of what the data interface is capable of. >>> >>> 1Gbs hard wired Ethernet? Sure ... if you only have 2 devices >>> connected, are running a single networked application ... and even >>> then all you'll get is 300-500Mbs max due to error correction (huge >>> overhead in Ethernet which increases logarithmically as nodes >>> activate), data scheduling problems and lots of negotiations >>> (e.g.ACK/NACKS, non-data packets ... ICMP for example, and other >>> high level protocols inherent in TCP/IP) between the devices. >>> >>> It doesn't much matter what network architecture you use ... the >>> overheads persist (as they were designed to do by the network >>> protocol inventors) and slow traffic way below the optimum. With >>> networks its important that little numbers like error detection and >>> recovery work ... especially in non-tolerant applications and devices. >> >> I think you're getting your layers pretty mixed up here. >> 1000base-T/802.3ab (Gigabit Ethernet) has no error correction (it has >> error detection), and given that's it's almost always switched won't >> have problems scaling as you add more devices and applications unless >> your switch is completely hopeless. Of course it has overheads that mean >> you won't actually get 1000Mbit/sec of user data (HTTP or whatever) but >> the performance is pretty predictable and quite close to the theoretical >> with modern computers. >> >> TCP/IP adds overheads to get its work done but there's no interference >> between nodes and applications there either. >> >>> >>> 2. Bottom line: WiFi is no more or less efficient than hard wired >>> network protocols. Indeed, low level WiFi protocols are typically >>> Ethernet protocols ... and hence subject to the SAME efficiency and >>> effectiveness limitations as the wired protocols they emulate. The >>> difference is that with WiFi you can overlay channels more easily >>> than you can on an Ethernet connection ... which doesn't handle >>> packet crowding very well at all. >> >> WiFi of course is working on a shared channel, while switched ethernet >> effectively has a separate channel for each connection. >> >> >> >> Hamish >> _______________________________________________ >> Link mailing list >> [email protected] <mailto:[email protected]> >> http://mailman.anu.edu.au/mailman/listinfo/link > _______________________________________________ Link mailing list [email protected] http://mailman.anu.edu.au/mailman/listinfo/link
