NetExt WG IETF-75 Mobility Session Suspend Ahmad Muhanna, et al.

Background In evolved network architecture which uses Proxy MIPv6 for network based mobility, voice call using IMS MAY not be supported. When a user have a proxy MIP6 session and receives a voice call, MN usually falls back to a legacy CS network. While the MN is attached to the CS network, it is NOT listening to the data traffic coming over the PMIP6 mobility session from the Mobile Access Gateway. MAG needs to drop all downlink data traffic to avoid MN paging and the termination of the mobile node mobility session. A mechanism is needed to keep the data session (i.e., suspend) to avoid reestablishing the PMIP6 data session one more time. Allowing the MAG to drop the MN downlink traffic without informing the LMA causes the LMA and the MAG to maintain different states of the MN session. In addition, when billing is collected on the LMA and the MAG, different billing is always expected and error is introduced in the billing system. An IETF based solution is required to avoid an SDO specific solution.

USECASES Any evolved packet based wireless network solution which uses PMIP6 for IP mobility while NOT having an IP based voice solution deployed. 3GPP2, HRPD with 1x CS Fallback. 3GPP, LTE with CS Fallback WiMAX with CS Fallback

Proposal When the MAG receives an indication of the MN mobility session suspension, MAG informs the LMA via a PBU message with Mobility Session Suspend (MSS) option included and S-Flag set. MAG update the MN Binding in the BUL and the MN routing entry to start dropping all downlink traffic being sent to the mobile node. After processing PBU with MSS option included, LMA updates the MN BCE and the MN routing entry to drop all downlink traffic. When the MN session resumes regular data activities, MAG sends a PBU with MSS option included and the Suspend flag cleared. This proposal keeps the MAG and the LMA synchronized w.r.t. the MN mobility session state.

Mobility Session Suspend Option MAG include MSS option in PBU with the S-Flag Set to indicate mobility session suspend starts. After MSS is exchanged between MAG and LMA, MN downlink traffic is dropped at the LMA | Type | Length |S| Reserved | Type TBD Length 2 S-Flag : 1 : Session Suspend 0 : Session Resume

Mobility Session Suspend/Resume MN LMA Voice Call Arrives MAG PBU with MSS S-Flag set RESUME Action: Suspend PBA with MSS S-Flag set Action: Suspend PBU with MSS S-Flag Clear RESUME PBA with MSS S-Flag Clear

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