WG82574L S LBA8 Intel, WG82574L S LBA8 Datasheet - Page 176

• Manufacturer Part Number: WG82574L S LBA8
• Manufacturer: Intel

Specifications of WG82574L S LBA8

• Operating Supply Voltage (typ): 3.3V
• Operating Temp Range: 0C to 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 64
• Lead Free Status / RoHS Status: Compliant

7.5
7.5.1
Note:
7.5.1.1
176
Write to Clear
The ICR register clears specific interrupt cause bits in the register after writing 1b to
those bits. Any bit that was written with a 0b remains unchanged.
Read to clear
All bits in the ICR register are cleared on a read to ICR.
802.1q VLAN Support
The 82574 provides several specific mechanisms to support 802.1q VLANs:
802.1q VLAN Packet Format
The following diagram compares an untagged 802.3 Ethernet packet with an 802.1q
VLAN tagged packet:
The CRC for the 802.1q tagged frame is re-computed, so that it covers the entire
tagged frame including the 802.1q tag header. Also, maximum frame size for an 802.1q
VLAN packet is 1522 octets as opposed to 1518 octets for a normal 802.3z Ethernet
packet.
802.1q Tagged Frames
For 802.1q, the Tag Header field consists of four octets comprised of the Tag Protocol
Identifier (TPID) and Tag Control Information (TCI); each taking two octets. The first
16 bits of the tag header makes up the TPID. It contains the protocol type, which
identifies the packet as a valid 802.1q tagged packet.
The two octets making up the TCI contain three fields:
• Optional adding (for transmits) and ping (for receives) of IEEE 802.1q VLAN tags.
• Optional ability to filter packets belonging to certain 802.1q VLANs.
• User Priority (UP)
• Canonical Form Indicator (CFI). Should be 0b for transmits. For receives, the
• VLAN Identifier (VID)
802.3 Packet
Type/Length
device has the capability to filter out packets that have this bit set. See the CFIEN
and CFI bits in the RCTL described in
Data
CRC
DA
SA
#Octets
46-1500
6
6
2
4
802.1q VLAN
Type/Length
802.1q Tag
Packet
CRC*
Data
DA
SA
section
#Octets
46-1500
10.2.5.1.
6
6
4
2
4
82574 GbE Controller—Inline Functions