DS33X42DK Maxim Integrated Products, DS33X42DK Datasheet - Page 70

• Manufacturer Part Number: DS33X42DK
• Description: Power Management Modules & Development Tools Ethernet Over PDH Ma PDH Mapping Devices
• Manufacturer: Maxim Integrated Products

Specifications of DS33X42DK

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8.16.4 Priority Coding with Multiple (Q-in-Q) VLAN Tags
Device operation with multiple VLAN tags is similar to operation with a single VLAN tag. The Ethernet Q-in-Q
format is similar to the case outlined above, except that a second VLAN tag is inserted after the Ethernet SA field.
The format of the VLAN Q-in-Q tagged frame is shown in Figure 8-14. Both VLAN tags include a PCP (User
Priority) value and a VLAN ID. The device only makes forwarding and scheduling decisions using the “outer-most”
VLAN tag located in Ethernet bytes # 13-16, and ignores additional tags. The user can configure an alternate
WAN-VLAN Q-in-Q or VLAN Tag Protocol ID (TPID) that is used instead of the default value of 8100 in the
SU.WETPID register. The user can configure an alternate LAN-VLAN Q-in-Q or VLAN Tag Protocol ID (TPID) that
is used instead of the default value of 8100h in the SU.LQTPID register. Some additional common TPIDs are 9100,
9200 and 88A8. See Section 8.16.6 for more information on programming the priority table.
Figure 8-14. VLAN Q-in-Q Field Format
Rev: 063008
Ethernet Byte #
________________________________________________ DS33X162/X161/X82/X81/X42/X41/X11/W41/W11
23+
10
11
12
13
14
15
16
17
18
19
20
21
22
1
2
3
4
5
6
7
8
9
Bit 7
7
7
3 Bit PCP Priority
3 Bit PCP Priority
Bit 6
8 (hex)
0 (hex)
8 (hex)
0 (hex)
Bit 5
Ethernet Type / Length (MSB)
Ethernet Type / Length (LSB)
Destination Address (DA)
Source Address (SA)
Bit 4
CFI
CFI
< Data Unit >
8 bits of VLAN ID
8 bits of VLAN ID
Bit 3
11
11
4 bits of VLAN ID
4 bits of VLAN ID
Bit 2
1 (hex)
0 (hex)
1 (hex)
0 (hex)
Bit 1
Bit 0
8
8
0
0
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