This isn't correct, or is misleading. It's kind of like saying "ethernet doesn't use TCP/IP" or "WiFi doesn't use TCP/IP" or "dialup modems don't use TCP/IP" or "DSL doesn't use TCP/IP" or "Cable doesn't use TCP/IP".
If you drop below the level of TCP/IP, to how the data is physically moved, then yes, you are below TCP/IP, and in that sense, cell networks don't use TCP/IP. However, they CARRY TCP/IP traffic. And that's what those IP addresses are -- IP addresses. You can establish TCP connections. TCP/IP is actually two protocols. IP is the lower-level of the two, handling addressing and routing. It is completely agnostic as to how the packets are transported. You could use carrier pigeons. Really! http://www.rfc-editor.org/rfc/rfc1149.txt I don't know if anybody's done it -- but it wouldn't surprise me. TCP is on top of IP, and gives you reliable transmission and end-to- end connection semantics. Now, perhaps you meant to contrast the situation with VOIP, where voice is carried over IP. Indeed, voice data is not (normally) carried over cell networks as TCP/IP, though it's possible. (Not necessarily acceptable, but possible). But every phone with a data plan is using the cell networks to carry TCP/IP. Your gateway address will be the address of the gateway server, but your IP address will be your IP address that your server uses to send traffic to you. I don't know the current state of the art for how stable your phone's IP address will be. I can tell you that my phone switches cell sites surprisingly often, but I've not watched the IP addresses simultaneously. But you don't switch IP addresses when you move from Access Point to Access Point on the same WiFi network. In theory, you could retain the same IP address for the life of your phone, with a sufficiently clever and powerful cell network. In practice, however, that's unreasonable. But perhaps someone can tell me just when it changes. And why, after rebooting, I have TWO? One for each tower? We're at the limits of my networking knowledge when we come to the specifics of how it's layered on top of the cellular network. BTW, Vertifi, this "Class B/Class C" terminology is long obsolete; addresses have not been allocated by that scheme for many years. It consumed too much IPv4 address space. Instead, the number of prefix bits is specified, like 192.168.0.0/24 -- where 24 is not necessarily a multiple of 8. I don't know if your server farm people are expecting "Class C" to refer to distinct networks, or simply using the term as a holdover, but treating it as the arbitrary distinction that it is. But certainly we should not import any significance to those IP addresses being allocated from some larger block than /24. They could all be from the same subnet, so far as the cellular network is concerned. This would be some network in some bunker somewhere, with a bunch of NAT servers, with multiple hot connections to various pieces of the backbone. The IP address assigned to the phone will be an address specific to the link between you and the next piece of equipment that actually treats your data as TCP/IP traffic. My iPhone reports it as 10.135.130.117; I've never seen it other than a 10.0.0.0/8 non- routable private address. This is translated via NAT further upstream, so servers on the other end see a routable IP address; at the moment, mine is 98.210.255.162. In theory, this can be different for every TCP connection! But there are a few things that care about connections with the same originating system -- active FTP being one. So normally, this synthetic IP address doesn't change, so long as you have one active TCP or recent connection, or recent UDP traffic, but after you've been idle or a bit, it purges its mapping tables, and on your next connection, you appear to come from a new IP address. This is really no different than any large enterprise NAT networking environment. Just bigger. Anyway -- while there are holes in my explanation, I don't think there's anything inaccurate. But I hate being wrong, so please jump in with any corrections or additions! On Feb 3, 7:38 am, Mike <michael.mo...@navteq.com> wrote: > The simple answer is that cell networks don't use TCP/IP. What you > see is the IP address of the gateway server that happens to have > generated the request. This could change on every request and is not > time based. > > Hope it helps. > > - Mike > NAVTEQ Network for Developershttp://NN4D.com > > On 3 Feb, 15:35, Vertifi <c...@eascorp.org> wrote: > > > > > Hello, > > > I have an app which performs some online functions to a web server > > farm we operate using URLConnection. I'm finding that the client IP > > address of the phone seems to change after a fairly brief period of > > inactivity. > > > For example, please see these timestamps and the corresponding client > > IP addresses: > > > 2010-02-03 09:46:47 / 32.152.30.98 > > 2010-02-03 09:47:05 / 32.152.30.98 > > 2010-02-03 09:57:21 / 32.152.218.197 > > 2010-02-03 09:59:53 / 32.152.23.19 > > > This is sitting in a stationary location (on an AT&T EDGE network) in > > my office. Is there some reason for this behavior? > > > Any advice would be greatly appreciated > > > Regards, > > Chris @ Vertifi -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
