Filter Creation
185
SWRU455A – February 2017 – Revised March 2017
Copyright © 2017, Texas Instruments Incorporated
Rx Filters
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Parent filter ID
•
Connection state
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Role
The advance features of defining counters is related to the following fields:
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Counter
•
Counter val
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Compare function
The following subsection describes the parameters required to create the filter trigger.
11.4.5.1 Parent Filter ID
The filter ID contains the ID of the parent filter; filters can be organized in a tree hierarchy.
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Setting ParenFilterId to 0 creates a root filter. All filters can be assigned as root.
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The parent filter ID is the ID of the filter which is the parent of the current filter.
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The filter rule is tested only if its parent match result is TRUE.
The parent filter can be from the same layer or a lower layer than the child filter.
The following defines the filter layer of each rule type.
Filter layers: The header rules can be specified in a tree form, but the rules must also preserve a layered
approach.
Therefore, a transport layer field (such as TCP or UDP source or destination ports) cannot be a parent of
a MAC header field (such as frame type).
presents which groups of header rule types can be parents of other header rule types. The
general guideline is that the lower the communication layer to which the header rule filter applies, the
more filters can depend on this filter.
NOTE:
When a filter contains a drop action, it cannot be a parent of any other filter, because if a
packet is dropped the tree traversal is stopped.
Table 11-6. Rule Types Layers
Group
Rule Types
Can be Parent of Rules from Group
A
FRAME_TYPE
FRAME_SUBTYPE
BSSID_ADDRESS
MAC_SRC_ADDRESS
MAC_DST_ADDRESS
FRAME_LENGTH
A, B, C, D
B
ETHER_TYPE
IP_VERSION
Multicast destination IPs (V4 and V6)
L1_PAYLOAD
B, C, D
C
Source IP (V4 and V6)
Unicast destination IP (V4 and V6)
IP PROTOCOL field (UDP, TCP, ICMP,
IGMP, and so forth)
C, D
D
Source port (UDP/TCP)
Destination port (UDP/TCP)
L4_PAYLOAD
D