Thus it is supposed that {HEAD ~ the as old acting SGSN} receives {TAIL ~ a GTP U packet} from a GGSN 
receives
Thus it is supposed that { HEAD ~ the as old acting SGSN } receives { TAIL ~ a GTP U packet } from a GGSN
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH