DS537 Datasheet, PDF (88/148 Pages) Xilinx, Inc – LogiCORE IP XPS LL TEMAC

LogiCORE IP XPS LL TEMAC (v2.03a)
Using transmit In-Band FCS mode of the TEMAC core is not allowed when using VLAN translation because the
user provided FCS field value would not be correct for the new VID field.
For double, triple, etc. tagged VLAN frames, only the outer VID will be translated.
The following TPID values are commonly used to flag VLAN frames: 0x8100, 0x9100, 0x9200, and 0x88a8 however,
the TPID values used to identify VLAN frames are programmable via the TPID registers.
Transmit and receive VLAN translation can be enabled separately with their respective parameters.
For VID values that do not need translated, the VLAN data table location associated with their value must be
initialized to that same value.
Receive Path
The receive operates similarly to the transmit side. The frame first passes through address filtering and validation
processing before being checked for a VLAN TPID.
Receive FCS stripping in the TEMAC core is required when using VLAN translation because the FCS field that
arrives with the frame will no longer be valid with the new TPID value. Please note that although receive stripping
is enabled, any padding if present will not be stripped due to the TYPE / LENGTH field of the receive frame
containing a VLAN tag rather than a length value.
VLAN Tagging and Double Tagging (Stacking)
VLAN tagging allows the TEMAC to insert a pre-defined VLAN tag in select Ethernet frames as they pass through
the core in either the transmit or receive direction.
X-Ref Target - Figure 57
6
bytes
Dest
Addr
6
2 ^{46 - 1500 bytes normal} 4
bytes bytes 46 - 9198 bytes jumbo bytes
Srce Type
Addr _/Len
Data
FCS
Dest
Addr
4
bytes
Srce VLAN Type
Addr _{Tag /Len}
Data
FCS
Dest Srce VLAN Type
Addr Addr _{Tag /Len}
Data
FCS
Dest
Addr
4
bytes
Srce VLAN VLAN Type
Addr Tag Tag _/Len
Data
Figure 57: VLAN Tagging
FCS
DS537_57_091909
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