Within this backbone , the gsns encapsulate the pdn packets and transmit ( tunnel ) them using the gprs tunneling protocol gtp . the interface between gsns is called gn / gp interface Gprs網(wǎng)絡(luò)中增加了gn 、 gp 、 gb等多個接口和網(wǎng)絡(luò)實體,其中g(shù)sn間的接口稱為gn或gp接口。