what are these interfaces

I wrote a code to gather the network usage statistics. When I ran it I got the below results. w开发者_StackOverflow中文版hat are the interfaces pdp0 and tun10 in these statistics. Are they 3g interfaces? I am running this app on samsung galaxy phone

{\"data\":{\"pdp0:\":{\"recv\":{\"packets\":\"8580\",\"bytes\":\"9227448\"},\"sent\":{\"packets\":\"5725\",\"bytes\":\"479019\"}},\"gre0:\":{\"recv\":{\"packets\":\"0\",\"bytes\":\"0\"},\"sent\":{\"packets\":\"0\",\"bytes\":\"0\"}},\"tunl0:\":{\"recv\":{\"packets\":\"0\",\"bytes\":\"0\"},\"sent\":{\"packets\":\"0\",\"bytes\":\"0\"}},\"usb0:\":{\"recv\":{\"packets\":\"0\",\"bytes\":\"0\"},\"sent\":{\"packets\":\"0\",\"bytes\":\"0\"}},\"lo:\":{\"recv\":{\"packets\":\"14908\",\"bytes\":\"713035\"},\"sent\":{\"packets\":\"14908\",\"bytes\":\"713035\"}}},\"ver\":\"1.4\",\"type\":\"netdev\",\"date\":\"2011-3-17 15:52:7\",\"user\":\"351863047772880\",\"time_stamp\":1303073527930}

PDP is a Packet Data Protocol interface and is likely your 2.5G or 3G network interface. See http://en.wikipedia.org/wiki/GPRS_Core_Network#PDP_Context

Tun interfaces are typically virtual software interfaces used to create network tunnels.

See http://en.wikipedia.org/wiki/TUN/TAP