DS537 Datasheet, PDF (87/148 Pages) Xilinx, Inc – LogiCORE IP XPS LL TEMAC

LogiCORE IP XPS LL TEMAC (v2.03a)
X-Ref Target - Figure 55
6
bytes
Dest
Addr
6
bytes
Srce
Addr
VLAN tag
4 bytes
2
bytes
TPID
8100
9100
9200
88a8
3
1 12
bits bit bits
Priority
VID
xxx
2 ^{46 - 1500 bytes normal} 4
bytes 46 - 9198 bytes jumbo bytes
Type
/Len
Data
FCS
Dest Srce
Addr Addr
TPID
8100
9100
9200
88a8
Priority
VID Type
yyy ^/Len
Data
Figure 55: VLAN VID Translation
FCS
DS537_55_091909
The TEMAC core will not recognize transmitting or receiving VLAN frames with a TPID other than 0x8100 when
VLAN mode is enabled. If VLAN mode is disabled, then the maximum length of a normal frame will not be
extended from 1518 to 1522 bytes Additionally, multiple tagging is also not supported because of the even larger
frame sizes.
To support multiple VLAN tagging and the use of TPID values other than 0x8100 in the outer tag, jumbo frame
mode must be used with basic VLAN mode disabled. This will eliminate automatic invalidating (by the TEMAC
core) of any frames that normally would be too large for "normal" frame sizes. The user must enable jumbo frame
mode and disable VLAN mode when needed for extended VLAN mode.
Transmit Path
When transmitting frames, the outgoing frame is detected as a VLAN frame by recognizing a VLAN Tag Protocol
Identifier value (TPID) in the Type/Length field by comparing it against user defined values in the VLAN TPID
Word 0 Register (TPID00 and TPID10) and VLAN TPID Word 1 Register (TPID01 and TPID11). Note that the TPID
values are shared between the receive and transmit paths.
Once a VLAN frame is identified, the 12-bit Unique VLAN Identifier (VID) is used to access The Transmit VLAN
Data Table (0 and 1) to supply a replacement VID value which is substituted into the outgoing frame.
X-Ref Target - Figure 56
Current
VID
0x000
0x001
0x002
0x003
New VID
(12 bits)
Strip enable bit
Tag enable bit
0xFFC
0xFFD
0xFFE
0xFFF
VLAN Data
Table
DS537_56_091909
Figure 56: VLAN Data Table
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