Hi Jeffrey, Why do you say there is no IP adjacency from gNB to UE? In the downlink, the gNB receives an IP packet from the UPF destined to itself. The gNB decapsulates such packet, and forwards the inner-exposed packet to the UE. Assuming the inner-exposed packet is IPv4, in such case the IPv4 Destination Address is the one of the UE.
RFC1812: "Adjacent - reachable without going through any IP routers" As far as I know, there is no IP router in between the gNB and the UE. Can you please clarify? Cheers, Pablo. -----Original Message----- From: Jeffrey (Zhaohui) Zhang <[email protected]> Sent: martes, 1 de junio de 2021 16:04 To: Pablo Camarillo (pcamaril) <[email protected]>; [email protected] Subject: RE: [DMM] [spring] note: WGLC on draft-ietf-dmm-srv6-mobile-uplane-11 Hi Pablo, Let me pull this up: ----------- Zzh4> gNB is certainly an IP device but its IP adjacency is in the "underlay" (transport network) not at the "overlay" (towards the UE). [PC5] The End.DX4 behavior (or the others) are not limited or restricted by "underlay" vs "overlay" IP adjacencies. The behavior is the same: remove the encaps, forward on a particular IP adjacency (regardless of its type). Zzh4> In the wireline/IETF VPN case, there is PE-CE IP adjacency. Traffic from CE is forwarded based on IP lookup in the VRF, whether the traffic to the CE requires IP lookup or not (i.e. whether per-CE or per-VPN label is used, or whether END.DT4/6/X is used). Zzh4> In case of gNB, UE-gNB is not IP adjacency and traffic to/from a UE does not have IP lookup (based on the inner IP header) at the gNB. --------- As I pointed out in zzh4>, the point is that there is *no IP adjacency* between UE and gNB. Practically, a device can implement the END.DX4/6 behavior to forward IP traffic over non-IP adjacencies. It's just that RFC8986 specifically calls out IP adjacencies. You may want to point it out and see if SR folks have any concerns. Jeffrey _______________________________________________ dmm mailing list [email protected] https://www.ietf.org/mailman/listinfo/dmm
