Receive Return RingsBCM5718 Programmer’s Guide
Broadcom®
January 29, 2016 • 5718-PG108-R Page 97
Class of Service Example
If either Start of IP Header, Start of TCP Header, or Start of UDP Header is specified, and the frame has no IP,
TCP, or UDP header, respectively, there is no frame match. The full set of rules provides a fairly rich selection
and filtering criteria.
Example: If you wanted to set a Class of Service (CoS) of 2 based on the eighth byte in the data portion of
an encapsulated IPX frame using Ethernet Type 2 having a value greater than 6, you could set up the rules
shown in Figure 16 on page 98.
15:13 Header RW Header Type specifies which header the offset is for:
• 000: Start of Frame (always valid)
• 001: Start of IP Header (if present)
• 010: Start of TCP Header (if present)
• 011: Start of UDP Header (if present)
• 100: Start of Data (always valid, context sensitive)
• 101–111: Reserved
–
12:8 Class RW The class this frame is placed into if the rule matches. 0:4, where 0 means
discard. The number of valid classes is the Number of Active Queues
divided by the Number of Interrupt Distribution Groups. Ring 1 has the
highest priority and Ring 4 has the lowest priority.
–
7:0 Offset RW Number of bytes offset specified by the header type. –
Table 24: Receive BD Rules Value/Mask Register
Bit Name RW Description Default
31:16 Mask – – –
15:0 Value – – –
Table 23: Receive List Placement Rules Array (memory offset 0x480–0x4ff) (Cont.)
Bit Name RW Description Default
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