Intel IXP400 manual Ixosalmbuf Port ID Field Format

Intel® IXP400 Software

Access-Layer Components: Ethernet Access (IxEthAcc) API

Table 19. IX_OSAL_MBUF Header Definitions for the Ethernet Subsystem (Sheet 3 of 3)

			Queue
Field	Description
		Eth	Eth	Eth	Eth
		Rx			Tx
			Rx	Tx
		Free			Done
	Transmit path VLAN functionality enable flag. A value of 0 indicates
	that all transmit path VLAN services, including VLAN ID-based
	filtering and VLAN ID-based tagging/untagging, should be disabled		W(5,6)
ixp_ne_flags.vlan_en	for the frame. A value of 1 indicates that these services should be			R
	enabled. This bit is unconditionally set by the NPE receive path
	firmware in VLAN-enabled builds and is unconditionally cleared by
	the NPE receive path firmware in non-VLAN-enabled builds.
	The internal QoS class of the frame (set by the NPE Ethernet
ixp_ne_qos_class	receive path firmware and used by the NPE transmit path firmware		W(6)	(3)
	to queue the frame for transmission within the NPE-internal priority
	queue).
ixp_ne_vlan_tci	The VLAN tag control information field of the frame (if any).		W(6)	R(4)
ixp_ne_dest_mac	The destination MAC address of the frame.		W(6)
ixp_ne_src_mac	The source MAC address of the frame.		W(6)

(R)- A value of “R” in a particular column indicates that the IX_OSAL_MBUF header field is read by the Ethernet NPE firmware when it extracts the IX_OSAL_MBUF (more accurately, a pointer to the IX_OSAL_MBUF) from the AQM queue specified in the column header. The Intel XScale core client software is responsible for ensuring that the field before inserting (a pointer to) the IX_OSAL_MBUF into the indicated AQM queue.

(W)- A value of “W” in a particular column indicates that the IX_OSAL_MBUF header field is written by the Ethernet NPE firmware before it inserts the IX_OSAL_MBUF (more accurately, a pointer to the IX_OSAL_MBUF) into the AQM queue specified in the column header. The Intel XScale core client software may be certain that these fields are valid in IX_OSAL_MBUFs that it extracts from the indicated AQM queue.

(1)- The ixp_ne_dest_port field is read only if the ixp_ne_flags.port_over flag indicates that the normal behavior of using the destination MAC address to determine the egress port is being overridden. These fields are meaningful only for multiported NPEs.

(2)- The ixp_ne_tag_mode field is read only if the ixp_ne_flags.tag_over flag indicates that the behavior specified by the VLAN Transmit Tagging Table should be overridden.

(3)- The NPE Ethernet transmit path firmware ignores the ixp_ne_qos_class field. Instead, it extracts the QoS class information from the QoS field of the EthTx queue entry, which must be set by the Intel XScale core software before the entry is enqueued.

(4)- The ixp_ne_vlan_tci field is read only if the output frame format is VLAN-tagged.

(5)- These fields are cleared by the NPE Ethernet receive path firmware, even though they have meaning only for the transmit path.

(6)- Although these fields may be considered to be valid only in the first IX_OSAL_MBUF in a chain of IX_OSAL_MBUFs containing a single received frame, the NPE Ethernet firmware may overwrite these fields in any and all IX_OSAL_MBUFs in the chain (regardless of their location within the chain).

Table 20. IX_OSAL_MBUF “Port ID” Field Format

7	6	5	4	3	2		1	0
		NPE ID				PORT ID

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	151