. With GPCS, packet parsing happens above the convergence sub-layer, resulting in parameters that are passed to the GPCS SAP for clas- sification. Upper layer packet parsing is left to the GPCS application. For the MS and BS, the upper layer protocol that is immediately on top of the IEEE 802.16 GPCS is identified by a TLV parameter and GPCS protocol type [1]. The GPCS protocol type is included in Control Service Flow Manage- ment (C-SFM) primitives and Dynamic Service Addition messages during connection establishment. The GPCS protocol defines a set of SAP parameters as the result of upper layer packet parsing. These are passed from the upper layer to the GPCS in addition to the data packet. For the MS and BS, the SAP parameters in the IEEE 802.16-2009 standard include SFID, MS MAC Address, data, and length [1]. In IEEE 802.16m, the MAC address is replaced by STID for user privacy protection. The GPCS allows multiplexing of multiple layer protocol types (e.g., IPv4, IPv6, IEEE 802.3 Ethernet) over the same IEEE 802.16 connection using appropriate upper layer protocol that supports multiplexing. This capability is signaled by the IEEE 802.16-2009 standard compliant mobile and base stations using the GPCS_PROTOCOL_TYPE parameter and by the IEEE 802.16m-compliant mobile and base stations using the Dynamic Service Addition/Change/Deletion messages to indicate that multiple protocols are supported for a connection/service flow. The multiplexing and de-multiplexing of multiple protocol data packets over an IEEE 802.16 connection/service flow is outside the scope of GPCS; however, interoperability between peer protocol layers must be ensured. The GPCS can further transparently support IEEE 802.1D, bridging over the IEEE 802.16 interface, since it requires the upper layer to provide the MS MAC Address and SFID with every packet, where the MS MAC Address and SFID can represent a port, and a port is either a unicast port or 162 CHAPTER 5 The IEEE 802. 16m Convergence Sub-Layer Upper Phall Layers Multiple Protocols Encapsu