Ethernet (ETH): media access control (MAC) with DMA controller RM0090
969/1422 Doc ID 018909 Rev 4
● RDES5: Receive descriptor Word5
Reserved.
Bits 11:8 PMT: PTP message type
These bits are encoded to give the type of the message received.
– 0000: No PTP message received
– 0001: SYNC (all clock types)
– 0010: Follow_Up (all clock types)
– 0011: Delay_Req (all clock types)
– 0100: Delay_Resp (all clock types)
– 0101: Pdelay_Req (in peer-to-peer transparent clock) or Announce (in ordinary or boundary
clock)
– 0110: Pdelay_Resp (in peer-to-peer transparent clock) or Management (in ordinary or
boundary clock)
– 0111: Pdelay_Resp_Follow_Up (in peer-to-peer transparent clock) or Signaling (for ordinary
or boundary clock)
– 1xxx - Reserved
Bit 7 IPV6PR: IPv6 packet received
When set, this bit indicates that the received packet is an IPv6 packet.
Bit 6 IPV4PR: IPv4 packet received
When set, this bit indicates that the received packet is an IPv4 packet.
Bit 5 IPCB: IP checksum bypassed
When set, this bit indicates that the checksum offload engine is bypassed.
Bit 4 IPPE: IP payload error
When set, this bit indicates that the 16-bit IP payload checksum (that is, the TCP, UDP, or
ICMP checksum) that the core calculated does not match the corresponding checksum field
in the received segment. It is also set when the TCP, UDP, or ICMP segment length does not
match the payload length value in the IP Header field.
Bit 3 IPHE: IP header error
When set, this bit indicates either that the 16-bit IPv4 header checksum calculated by the
core does not match the received checksum bytes, or that the IP datagram version is not
consistent with the Ethernet Type value.
Bits 2:0 IPPT: IP payload type
if IPv4 checksum offload is activated (IPCO=1, ETH_MACCR bit 10), these bits
indicate the type of payload encapsulated in the IP datagram. These bits are ‘00’ if there is an IP
header error or fragmented IP.
– 000: Unknown or did not process IP payload
– 001: UDP
–010: TCP
– 011: ICMP
– 1xx: Reserved
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