Data Sheet

Ethernet Controller I210 —Packet Types
872
• The Upper-Layer Packet Length in the pseudo-header is the length of the upper-layer header and
data (e.g., TCP header plus TCP data). Some upper-layer protocols carry their own length
information (e.g., the Length field in the UDP header); for such protocols, that is the length used in
the pseudo- header. Other protocols (such as TCP) do not carry their own length information, in
which case the length used in the pseudo-header is the Payload Length from the IPv6 header,
minus the length of any extension headers present between the IPv6 header and the upper-layer
header.
• Unlike IPv4, when UDP packets are originated by an IPv6 node, the UDP checksum is not optional.
That is, whenever originating a UDP packet, an IPv6 node must compute a UDP checksum over the
packet and the pseudo-header, and, if that computation yields a result of zero, it must be changed
to hex FFFF for placement in the UDP header. IPv6 receivers must discard UDP packets containing a
zero checksum, and should log the error.
A type 0 Routing header has the following format:
• Next Header - 8-bit selector.
— Identifies the type of header immediately following the Routing header.
— Uses the same values as the IPv4 Protocol field [RFC-1700 et seq.].
• Hdr Ext Len - 8-bit unsigned integer. Length of the Routing header in 8-octet units, not including
the first 8 octets. For the Type 0 Routing header, Hdr Ext Len is equal to two times the number of
addresses in the header.
•Routing Type - 0.
• Segments Left - 8-bit unsigned integer. Number of route segments remaining, i.e., number of
explicitly listed intermediate nodes still to be visited before reaching the final destination. Equal to
“n” at the source node.
Reserved - 32-bit reserved field. Initialized to zero for transmission; ignored on reception.
• Address[1...n] - Vector of 128-bit addresses, numbered 1 to n.
The UDP header is always 8 bytes in size with no options.
Table A-9. IPv6 Routing Header (Traditional Representation)
Next Header Hdr Ext Len
Routing Type
“0”
Segments Left
“n”
Reserved
Address[1]
Address[2]
…
Final Destination Address[n]
Table A-10. UDP Header (Traditional Representation)
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
Source Port Destination Port
Length Checksum