LAN9353 Datasheet, PDF (403/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
If the IPv6 packet does not contain a Routing header, then the final IPv6 destination address is the destina-
tion address contained in the IPv6 header.
If the IPv6 packet does contain a Routing header, then the final IPv6 destination address is the address in
the last element of the Routing header.
Note: The original UDP checksum is calculated over the entire UDP payload as indicated by the UDP length field
and not the assumed PTP packet length.
Note: The original UDP checksum calculation does not included layer 2 pad bytes, if any.
Note: The two bytes beyond the end of the PTP message are located by using the messageLength field from the
PTP header.
• The frame FCS is recomputed.
If the original FCS was invalid, a bad FCS is forced.
• If the frame has a receive symbol error(s), a receive symbol error indication will be propagated at the same nibble
location(s).
Note: FCS and UDP checksums are only updated if the frame was actually modified. If no modifications are done,
the existing FCS and checksums are left unchanged.
15.2.1.5 Ingress Message Filtering
PTP messages can be filtered upon receive. Following the determination of packet format and qualification of the packet
as a PTP message above, the PTP header is checked for ANY of the following.
• The messageType field of the PTP header is checked and those messages that have their RX PTP Message Type
Filter Enable (RX_PTP_MSG_FLTR_EN[15:0]) bits in the 1588 Port x RX Filter Configuration Register (1588_RX-
_FILTER_CONFIG_x) set will be filtered. Typically Delay_Req and Delay_Resp messages are filtered in peer-to-
peer transparent clocks.
• The versionPTP field of the PTP header is checked against the RX PTP Version (RX_PTP_VERSION[3:0]) field in
the 1588 Port x RX Timestamp Configuration Register (1588_RX_TIMESTAMP_CONFIG_x). If the RX PTP Ver-
sion Filter Enable (RX_PTP_VERSION_FLTR_EN) bit in the 1588 Port x RX Filter Configuration Register
(1588_RX_FILTER_CONFIG_x) is set, messages with a non-matching version will be filtered. A version setting of
0 allows any PTP version and would not cause filtering.
Note: Support for the IEEE 1588-2002 (v1) packet format is not provided.
• If enabled via the RX PTP Domain Filter Enable (RX_PTP_DOMAIN_FLTR_EN) bit in the 1588 Port x RX Filter
Configuration Register (1588_RX_FILTER_CONFIG_x), messages whose domainNumber field in the PTP header
does not match the RX PTP Domain (RX_PTP_DOMAIN[7:0]) value in the 1588 Port x RX Timestamp Configura-
tion Register (1588_RX_TIMESTAMP_CONFIG_x) will be filtered.
• If enabled via the RX PTP Alternate Master Filter Enable (RX_PTP_ALT_MASTER_FLTR_EN) bit in the 1588 Port
x RX Filter Configuration Register (1588_RX_FILTER_CONFIG_x), messages whose alternateMasterFlag in the
flagField of the PTP header is set will be filtered.
At the end of the frame, the frame’s FCS and the UDP checksum (for IPv4 and IPv6 formats) are verified. FCS checking
can be disabled using the RX PTP FCS Check Disable (RX_PTP_FCS_DIS) bit in the 1588 Port x RX Timestamp Con-
figuration Register (1588_RX_TIMESTAMP_CONFIG_x). UDP checksum checking can be disabled using the RX PTP
UDP Checksum Check Disable (RX_PTP_UDP_CHKSUM_DIS) bit in the same register.
Note: A IPv4 UDP checksum value of 0x0000 indicates that the checksum is not included and is considered a
pass. A IPv6 UDP checksum value of 0x0000 is invalid and is considered a fail.
Note: For IPv6, the UDP checksum calculation includes the IPv6 Pseudo header. Part of the IPv6 Pseudo header
is the final IPv6 destination address.
If the IPv6 packet does not contain a Routing header, then the final IPv6 destination address is the destina-
tion address contained in the IPv6 header.
Note:
Note:
If the IPv6 packet does contain a Routing header, then the final IPv6 destination address is the address in
the last element of the Routing header.
The UDP checksum is calculated over the entire UDP payload as indicated by the UDP length field and not
the assumed PTP packet length.
The UDP checksum calculation does not included layer 2 pad bytes, if any.
 2015 Microchip Technology Inc.
DS00001925A-page 403