Section: 10.5.6.12 Traffic Flow Template
Content: The purpose of the traffic flow template information element is to specify the TFT parameters and operations for a PDP context. In addition, this information element may be used to transfer extra parameters to the network (e.g. the Authorization Token; see 3GPP TS 24.229[ IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3 ]  [95]). The TFT may contain packet filters for the downlink direction, the uplink direction or packet filters that are applicable to both directions. The packet filters determine the traffic mapping to PDP contexts. The downlink packet filters shall be used by the network and the uplink packet filters shall be used by the MS. A packet filter that is applicable to both directions shall be used by the network as a downlink packet filter and by the MS as an uplink packet filter. The traffic flow template is a type 4 information element with a minimum length of 3 octets. The maximum length for the IE is 257 octets. NOTE 1: The IE length restriction is due to the maximum length that can be encoded in a single length octet. NOTE 2: A maximum size IPv4 packet filter can be 36 bytes. Therefore, 7 maximum size IPv4 type packet filters can fit into one TFT IE, i.e. if needed not all packet filter components can be defined into one message. A maximum size IPv6 packet filter can be 54 bytes. Therefore, only 4 maximum size IPv6 packet filters, plus the last packet filter which can contain max 38 octets can fit into one TFT IE. However, using "Add packet filters to existing TFT", it's possible to create a TFT data structure including 16 maximum size IPv4 or IPv6 filters. The traffic flow template information element is coded as shown in figure 10.5.144/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  and table 10.5.162/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] . NOTE 3: The 3GPP TS 24.301[ Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3 ]  [120] reuses the traffic flow template information element for the purpose of the traffic flow aggregate description, where the use of individual TFT parameters, e.g. the packet filter identifier in the parameter list, can differ from this specification. Figure 10.5.144/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Traffic flow template information element Figure 10.5.144a/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Packet filter list when the TFT operation is "delete packet filters from existing TFT" (z=N+3) Figure 10.5.144b/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Packet filter list when the TFT operation is "create new TFT", or "add packet filters to existing TFT" or "replace packet filters in existing TFT" Figure 10.5.144c/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Parameters list Table 10.5.162/3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] : Traffic flow template information element