more clear about checksum error dropping datagram

This commit is contained in:
Randy Bush 2019-07-17 13:23:10 -07:00
parent 6390c249d8
commit 7b6b684423

View file

@ -137,7 +137,8 @@
<t hangText="Clos:">A hierarchic subset of a crossbar switch
topology commonly used in data centers.</t>
<t hangText="Datagram:">The L3DL content of a single Layer 2
frame. A full L3DL PDU may be packaged in multiple Datagrams.</t>
frame, sans Ethernet framing. A full L3DL PDU may be packaged in
multiple Datagrams.</t>
<t hangText="Encapsulation:">Address Family Indicator and
Subsequent Address Family Indicator (AFI/SAFI). I.e. classes of
layer 2.5 and 3 addresses such as IPv4, IPv6, MPLS, etc.</t>
@ -158,8 +159,8 @@
of the largest packet that can be sent on a medium, see <xref
target="RFC1122"/> 1.3.3.</t>
<t hangText="PDU:">Protocol Data Unit, an L3DL application layer
message. A PDU may need to be broken into multiple Datagrams to
make it through MTU or other restrictions.</t>
message. A PDU's content may need to be broken into multiple
Datagrams to make it through MTU or other restrictions.</t>
<t hangText="RouterID:">An 32-bit identifier unique in the
current routing domain, see <xref target="RFC6286"/>.</t>
<t hangText="Session:">An established, via OPEN PDUs, session
@ -403,11 +404,13 @@
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version |L| Datagram Number |
| Version |L| Transmission Sequence Number | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Datagram Length | Checksum ~
| Datagram Number | Datagram Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ | Payload... ~
| Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Payload... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
</artwork>
</figure>
@ -428,7 +431,7 @@
<t hangText="Transmission Sequence Number:">A 16-bit strictly
increasing unsigned integer identifying this PDU, possibly across
retransmissions, that wraps from 2^24-1 to 0. The initial value
retransmissions, that wraps from 2^16-1 to 0. The initial value
is arbitrary. See <xref target="RFC1982"/> on DNS Serial Number
Arithmetic for too much detail on comparison and incrementing a
wrapping sequence number.</t>
@ -443,9 +446,11 @@
a datagram to 2^16 octets.</t>
<t hangText="Checksum:">A 32 bit hash over the Datagram to detect
bit flips, see <xref target="checksum"/>. If a Datagram fails a
checksum verification, the entire PDU is invalid and should be
silently discarded.</t>
bit flips, see <xref target="checksum"/>.</t>
<t>If a Datagram fails checksum verification, the datagram is
invalid and should be silently discarded. The sender will
retransmit the PDU, and the receiver can assmble it.</t>
<t hangText="Payload:">The PDU being transported or a fragment
thereof.</t>