DS537 Datasheet, PDF (38/148 Pages) Xilinx, Inc – LogiCORE IP XPS LL TEMAC

LogiCORE IP XPS LL TEMAC (v2.03a)
see the section on VLAN functions (Extended VLAN Support, page 85) for more information about extended
VLAN functions.
X-Ref Target - Figure 17
0
TPID value 3
15 16
TPID value 2
31
DS537_17_091909
Figure 17: VLAN TPID Word 1 Register (offset 0x03C and 0x07C)
Table 20 shows the VLAN TPID Word 1 Registers bit definitions.
Table 20: VLAN TPID Word 1 Registers Bit Definitions
Bit(s)
Name
Core
Access
Reset Value
Description
16 - 31 TPID value 2 Read/Write
0x0
TPID Value 2. These bits represent one TPID value that will be used
for recognizing VLAN frames for both the transmit and receive paths.
0 - 15 TPID value3 Read/Write
0x0
TPID Value 3. These bits represent one TPID value that will be used
for recognizing VLAN frames for both the transmit and receive paths.
Multicast Address Table (0 and 1)
The Multicast Address Table entry is shown in Figure 19. The multicast address table is only present when extended
multicast address filtering is selected at build-time (C_TEMACx_MCAST_EXTEND = 1). The purpose of the table
is to allow the xps_ll_temac to support reception of frames addressed to many multicast addresses while providing
some of the filtering in hardware to off load some of the overhead required for filtering in software.
While a MAC multicast address is defined as any 48 bit MAC address that has bit 0 (LSb) set to 1 (for example
01:00:00:00:00:00), in most cases the MAC multicast address is created from a IP multicast address as shown in
Figure 18.
X-Ref Target - Figure 18
224.0.0.0 to 239.255.255.255 32-bit IP multicast address
(typically shown as four
multicast bit
8-bit values in decimal)
(bit 0 byte 0)
lower 23 bits
01:00:5e:00:00:00 to 01:00:5e:7f:ff:ff 48-bit MAC destination
Constant
multicast address
(typically shown as six
8-bit values in decimal)
Hardware look-up upper 15 bits
of 23 bits for ‘1’ or ‘0’
32K x 1
Table
If ‘1’, pass up to
if ‘0’, drop _{software to make decision.}
this frame.
DS537_18_091909
Figure 18: Mapping IP Multicast Addresses to MAC Multicast Addresses
When a multicast address frame is received while this extended multicast filtering is enabled, the xps_ll_temac first
verifies that the first 24 bits are 01:00:5E and then will use the upper 15 bits of the unique 23 bit MAC multicast
address to index this memory. If the associated memory location contains a 1 then the frame is accepted and passed
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