BCM1250/BCM1125/BCM1125H
User Manual
10/21/02
B r o a d c o m C o r p o r a t i o n
Page
316
Section 9: Ethernet MACs
Document
1250_1125-UM100CB-R
7
allm_en
1’b0
When this bit is set all multicast packets are accepted. When it is clear multicast
packets will only be accepted if they match in the Exact or Hash filters.
Used in both Ethernet and Packet FIFO modes.
15:8
iphdr_offset
8'b0
Byte in the packet (counting from 1) of the IP header for checking the IPv4 header
checksum. This is normally 15, but may be different if encapsulation headers are
prepended. This offset is also used by the TCP checksum checking.
Used only in Ethernet mode.
23:16
rx_crc_offset
8'b0
System Revision PERIPH_REV3 and later only.
Sets the offset for CRC checking to begin in received packets. Bits 18:16 MUST be
3'b000.
Used in both Ethernet and Packet FIFO modes.
31:24
rx_pkt_offset
8'b0
System Revision PERIPH_REV3 and later only.
Sets the offset for the Ethernet frame in received packets. Bits 26:24 MUST be 3'b000.
Used in both Ethernet and Packet FIFO modes.
32
fwdpause_en
1'b0
System Revision PERIPH_REV3 and later only.
If this bit is set then Pause Frames will not be processed by the hardware and will be
accepted and passed to the DMA engine as though they had passed the address filter.
This allows software to do pause frame flow control (for example to only disable the
best-effort tx DMA channel when a pause is requested, but allow the priority traffic to
continue).
Used only in Ethernet mode.
33
vlan_det_en
1'b0
System Revision PERIPH_REV3 and later only.
If this bit is set then 4 is added to the ip_hdr_offset if the type field in the MAC header
(i.e. at mac_h12 and +13) is the VLAN type 81-00. This allows the correct IP
header offset to be used for a network with a mix of VLAN and non-VLAN packets. In
addition when the 81-00 type is detected the vlan_pkt bit (written to bit 1 of the dscr_b
"options" field i.e. just above the bad_tcpcs bit) will be set and the pkt_type field in the
status will come from decoding the two bytes following the VLAN tag (i.e. the packet
type from the untagged packet).
Used only in Ethernet mode.
41:34
rx_ch_msn_sel
8'b0
System Revision PERIPH_REV3 and later only.
This field specifies the offset of the upper four bits of the channel selection index when
the split_ch_sel bit is set in the
mac_cfg
register. Note that if
rx_ch_msn_sel <= {rx_ch_sel_msb,rx_ch_sel} the channel selected is
UNPREDICTABLE.
Used in both Ethernet and Packet FIFO modes.
63:42 reserved 22'b0
Reserved
Table 192: MAC Receive Address Filter Control Registers
(Cont.)
mac_adfilter_cfg_0 -
00_1006_4200
mac_adfilter_cfg_1 -
00_1006_5200
mac_adfilter_cfg_2 -
00_1006_6200
This register is used in both Ethernet and Packet FIFO modes
Bits
Name
Default
Description