Information

Enhanced Three-Speed Ethernet Controllers
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
16-144 Freescale Semiconductor
16.6.4 Quality of Service (QoS) Provision
This section describes the quality of service support features of this device. It includes a parser which
extracts vital packet properties and passes then to the filer which essentially acts as a frame classifier.
16.6.4.1 Receive Parser
The receive parser parses the incoming frame data and generates filer properties and frame control block
(FCB). The receive parser composes of the Ethernet header parser and L3/L4 parser.
The Ethernet header parser parses only L2 (ethertype) headers. It is enabled by RCTRL[PRSDEP] != 0. It
has the following key features:
• Extraction of 48-bit MAC destination and source addresses
• Extraction and recognition of the first 2-byte ethertype field
• Extraction and recognition of the final 2-byte ethertype field
• Extraction of 2-byte VLAN control field
• Walk through MPLS stack and find layer 3 protocol
• Walk through VLAN stack and find layer 3 protocol
• Recognition of the following ethertypes for inner layer parsing
— LLC and SNAP header
2–3 0–1 — Reserved
2–7 RQ Receive queue index. This index was selected by the eTSEC Rx Filer (from a matching Filer rule’s
RQCTRL[Q] field) when it accepted the associated frame. If filing is not enabled, RQ is zero. Note
that the 3 least significant bits of RQ correspond with the RxBD ring index whenever
RCTRL[FSQEN] = 0.
8–15 PRO If IP = 1, PRO is set as follows:
• PRO=0xFF for a fragment header or a back to back route header
•PRO=0xnn for an unrecognized header, where nn is the next protocol field
• PRO=(TCP/UDP header), as defined in the IANA specification, if TCP or UDP header is found
If IP = 0, PRO is undefined.
Note that the eTSEC parser logic stops further parsing when encountering an IP datagram that
has indicated that it has fragmented the upper layer protocol. This in general means that there is
likely no layer 4 header following the IP header and extension headers. eTSEC leaves the
RxFCB[PRO] and RQFPR[L4P] fields 0xFF in this case, which usually means that there was no IP
header seen. In this case RxFCB[IP] and optionally RxFCB[IP6] is set. IP header checksumming
operates and performs as intended. Most of the time, the eTSEC updates the RxFCB[PRO] field
and RQFPR[L4P] fileds with whatever value was found in the protocol field of the IP header. See
Section 16.5.3.3.8, “Receive Queue Filer Table Property Register (RQFPR),” for a description of
RQFPR.
4–5
0–15 — Reserved
6–7 0–15 VLCTL VLAN control word as per IEEE Std. 802.1Q. The lower 12 bits comprise the VLAN identifier. Valid
only if VLN = 1.
Table 16-137. Rx Frame Control Block Descriptions (continued)
Bytes Bits Name Description