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IXP400 Software
Access-Layer Components: Ethernet Database (IxEthDB) API
Programmer’s Guide IXP400 Software Version 2.0 April 2005
Document Number: 252539, Revision: 007 179
done using ixEthDBUserFieldGet(). Note that neither IxEthDB, nor the NPE microcode, ever uses
the user-defined field for any internal operation and it is not aware of the significance of its
contents. The field is only stored as a pointer.
The user-defined field may be added to any of the IxEthDB Intel XScale core-based databases:
• XScale Learning/Filtering Database (including VLAN-related records)
• Ethernet Firewall Database
• WiFi Header Conversion Database
10.4.4.2 Database Clear
The IxEthDB component provides a function for removing port-specific records from each
database listed above. It also provides the capability for removing one or more records from one,
many, or all databases.
10.4.5 Dependencies on IxEthAcc Configuration
One of the functions of IxEthAcc is to configure the MAC sub-component of each NPE. In order
for many of the features provided in IxEthDB to work properly, the MAC must be configured
appropriately.
10.4.5.1 Promiscuous-Mode Requirement
Ethernet Filtering is operational only when a port is configured to operate in promiscuous mode.
Otherwise the frames will be filtered according to normal MAC filtering rules. Those filtering rules
are that the frame is received only if one of the following is true:
• The destination address matches the port address
• The destination address is the broadcast address or if the destination is a multicast address
subscribed to by the port
• The frame is a broadcast/multicast frame.
Configuration of promiscuous mode is described in the section for IxEthAcc, “MAC Filtering” on
page 146.
10.4.5.2 FCS Appending
Several NPE features controlled by IxEthDB cause changes to the frame data such that a
previously calculated Frame Check Sequence will be invalid. IxEthAcc provides a set of functions
that can instruct the NPE to remove the FCS on received Ethernet frames, or calculate and append
the FCS on frames prior to transmission. It is the responsibility of the client application to
configure the FCS settings for each port properly.
Receive Traffic
FCS appending should be disabled, or the FCS data should be ignored when a port is configured
for the following features:
• VLAN Ingress tagging/untagging
• 802.3 to 802.11 Frame Conversion