BOPI 10 BR/2023 REPERTOIRE NUMERIQUE 21 Fig. 1 Consulter le mémoire ________________________________________ (11) 21198 (51) H04L 29/08 (2018.01); H04L 29/12 (2018.01); H04L 29/14 (2018.01) (21) 1202300070 - PCT/EP2021/075757 (22) 20/09/2021 (30) US n° 63/081,066 du 21/09/2020 (54) Restoration of a PDN connection at PGW failure. (72) YANG, Yong (SE) (73) TELEFONAKTIEBOLAGET LM ERICSSON (PUBL), 16483 STOCKHOLM (SE) (74) ALEMBONG OSWALD AMIN, S/C Von Seidels Cameroon Sarl, EasyOffice Building, Centre de l'Artisanat, Carrefour Intendance, B.P. 30188, YAOUNDE (CM) (57) Disclosed herein is a method of operation of a cellular communications system 500. The method comprises: at a MME 602: receiving 700 an attach request from a UE 512; sending 702 a location update request to a HSS 606; receiving 704 a location update acknowledgement from the HSS 606; sending 706 a DNS query request to a DNS 618, the DNS query comprising an APN FQDN; receiving 708 a DNS query response from the DNS 618, the DNS query response comprising information that: indicates a plurality of candidate PGWs 614 that satisfy the DNS query request; and indicates at least two PGWs 614-1 and 614-2 belonging to a same PGW set, the at least PGWs comprising a first PGW 614-1 and a second PGW 614-2; selecting 710 the first PGW 614-1 ; sending 712, to a SGW 604, a first create session request that comprises information that indicates the first PGW 614-1; receiving 718 a first create session response from the SGW 604; sending 720 an attach accept to the UE 512; and at the SGW 604: receiving 712 the first create session request from the MME 602; forwarding 714 the first create session request to the first PGW 614; receiving 716 the first create session response from the first PGW 614; and forwarding 718 the first create session response to the MME 602.
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