Intel IXP400 manual Receive Priority Queuing, QoS on Receive for 802.1Q Tagged Frames

Intel® IXP400 Software

Access-Layer Components: Ethernet Database (IxEthDB) API

10.3.5.2Receive Priority Queuing

Incoming frames will be classified into an internal traffic class, either by mapping the 802.1Q priority field (if available) into an internal traffic class or by using the default traffic class associated with the incoming port. The incoming frame will be placed on a receive queue depending on its traffic class. Up to four traffic classes and associated queues are supported. Traffic classes are ordered in their priority order, with 0 being the lowest priority.

Figure 56. QoS on Receive for 802.1Q Tagged Frames

				Rx
Incoming frame (802.1Q tagged)
Preamble	Start frame	Dest MAC addr	Src MAC addr	0x8100	Pri	CFI	VLAN ID	Len	Data	Pad	FCS
				User priority: 0..7
				Traffic class queue selector
		User Priority	Traffic class
		0	2
		1	0
		7	3			Traffic class 0 queue
		Priority regeneration table					Traffic class 1 queue
									Traffic class 2 queue
										Traffic class 3 queue
		EthDB							EthAcc

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