Intel PCI User Manual

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This filter checks the next headers looking for an IP header. It is capable of decoding Ethernet II, 

Ethernet SNAP, and IEEE 802.3ac headers. It skips past any of these intermediate headers and 
looks for the IP header. The receive configuration settings determine which next headers are 

accepted. See the various receive control configuration registers such as RCTL (RCTL.VFE), VET, 

and VFTA.

This filter checks for valid IPv4 headers. The version field is checked for a correct value (4). IPv4 
headers are accepted if they are any size greater than or equal to 5 (dwords). If the IPv4 header is 

properly decoded, the IP checksum is checked for validity. The RXCSUM.IPOFL bit must be set 

for this filter to pass.

This filter checks for valid IPv6 headers, which are a fixed size and have no checksum. The IPv6 
extension headers accepted are: Hop-by-Hop, Destination Options, and Routing. The maximum 

size next header accepted is 16 dwords (64 bytes).

All of the IPv6 extension headers supported by the Ethernet controller have the same header 

structure:

•

NEXT HEADER is a value that identifies the header type. The supported IPv6 next headers 

values are: 

— Hop-by-Hop = 00h

— Destination Options = 3Ch

— Routing = 2Bh

•

HDR EXT LEN is the 8 byte count of the header length, not including the first 8 bytes. For 

example, a value of 3 means that the total header size including the NEXT HEADER and 

HDR EXT LEN fields is 32 bytes (8 + 3*8).

— The RXCSUM.IPV6OFL bit must be set for this filter to pass.

This filter checks for a valid UDP or TCP header. The prototype next header values are 11h and 

06h, respectively. The RXCSUM.TUOFL bit must be set for this filter to pass.

The transmission process for regular (non-TCP Segmentation packets) involves:

•

The protocol stack receives from an application a block of data that is to be transmitted.

Next Header

Hdr Ext Len