Section: 6.2A IP header compression
Content: The UE and the MME may support robust header compression (ROHC) framework (see IETF RFC 5795 [37]) for IP header compression if control plane CIoT EPS optimization is supported for PDN connections of IP PDN type. If IP header compression for control plane CIoT EPS optimization is supported, the ROHC profiles defined in 3GPP TS 36.323[ Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification ]  [38] may be supported. The ROHC configuration is negotiated and established during the UE requested PDN connectivity procedure as specified in clause 6.5.1. Both the UE and the MME indicate whether IP header compression for control plane CIoT EPS optimization is supported during attach and tracking area updating procedures (see clauses 5.5.1 and 5.5.3). The ROHC configuration can be re-negotiated by using the UE requested bearer resource modification procedure or the EPS bearer context modification procedure as specified in clauses 6.4.3 and 6.5.4.