[{"name":"S2-2202784","title":"LS from BBF: ATSSS and Co-located AGF-UPF procedures","source":"BBF","contact":"Lincoln Lavoie","contact-id":39231,"tdoctype":"LS in","for":"Information","abstract":"Dear colleagues, During the course of our deliberations we have come to realize that there are some potential issues with the use of ATSSS with a supporting UPF that is collocated with a W-AGF. 1) In the scenario where a multi access 5G-RG is registered on both a 3GPP access and a WWC non-3GPP access it is not clear that the AMF will have wAGF identities information available to present to the selected SMF if an MA-PDU session is initiated on the 3GPP access. The only references to the availability of wAGF identities information is when it is included in the N2 UPLINK NAS TRANSPORT container for the PDU session establishment transactions. We believe that it is essential\/beneficial\/required to ensure that a UPF collocated with AGF can be selected also in this scenario. One option to achieve this would be that the AMF would need to retain wAGF identities information obtained during the registration process in wireline access such that it is available to the selected SMF irrespective of the access used for MA-PDU session establishment. 2) In the scenario where a multi-access equipped 5G-RG initially is registered on a 3GPP access and the WWC non-3GPP access is unavailable, wAGF identities information will not be available and therefore selection of a collocated AGF-UPF would appear to be impossible. When the WWC non-3GPP access returned to availability one method of redress would be to force any MA-PDU capable PDU sessions to be torn down and re-established to ensure proper UPF selection. We would note that one potential generalized solution would be the retention of the most recent wAGF identifies information in some form of persistent storage such that it was available for UPF selection in any of the cases above. This would address the majority of cases for co-located UPF selection and preserve session continuity, but would not completely eliminate the requirement for procedures to force UPF reselection. Your feedback on the scenarios and options for resolution outlined above would be appreciated. On the assumption that a solution is forthcoming, can you please advise as to a potential timeline for publication. We look forward to continuing our fruitful relationship. Thanks, Lincoln Lavoie Broadband Forum Technical Committee Chair","secretary_remarks":"Response drafted in S2-2202242. Final response in S2-2203021","agenda_item_sort_order":6,"ainumber":"4.1","ainame":"Common issues and Incoming LSs","tdoc_agenda_sort_order":10480,"status":"replied to","reservation_date":"2022-03-29 15:34:29","uploaded":"2022-03-29 17:47:55","revisionof":"","revisedto":"","release":"","crspec":"","crspecversion":"","workitem":"","crnumber":"","crrevision":"","crcategory":"","tsg_crp":"","lsreplyto":"","lsto":"SA WG2","Cc":"CableLabs","lsoriginalls":"LIAISE-519","lsreply":"S2-2203021, S2-2203021","link":"https:\/\/www.3gpp.org\/ftp\/tsg_sa\/WG2_Arch\/TSGS2_150E_Electronic_2022-04\/Docs\/S2-2202784.zip","group":"S2","meeting":"S2-150-e","year":2022,"uicc_affected":null,"me_affected":null,"ran_affected":null,"cn_affected":null,"clauses_affected":null,"crsinpack":null,"crsinpacknumber":0}]