target = "https://www.rfc-editor.org/rfc/rfc9000#section-14"

# 14.  Datagram Size
#
# A UDP datagram can include one or more QUIC packets.  The datagram
# size refers to the total UDP payload size of a single UDP datagram
# carrying QUIC packets.  The datagram size includes one or more QUIC
# packet headers and protected payloads, but not the UDP or IP headers.
# 
# The maximum datagram size is defined as the largest size of UDP
# payload that can be sent across a network path using a single UDP
# datagram.  QUIC MUST NOT be used if the network path cannot support a
# maximum datagram size of at least 1200 bytes.
# 
# QUIC assumes a minimum IP packet size of at least 1280 bytes.  This
# is the IPv6 minimum size [IPv6] and is also supported by most modern
# IPv4 networks.  Assuming the minimum IP header size of 40 bytes for
# IPv6 and 20 bytes for IPv4 and a UDP header size of 8 bytes, this
# results in a maximum datagram size of 1232 bytes for IPv6 and 1252
# bytes for IPv4.  Thus, modern IPv4 and all IPv6 network paths are
# expected to be able to support QUIC.
# 
#    |  Note: This requirement to support a UDP payload of 1200 bytes
#    |  limits the space available for IPv6 extension headers to 32
#    |  bytes or IPv4 options to 52 bytes if the path only supports the
#    |  IPv6 minimum MTU of 1280 bytes.  This affects Initial packets
#    |  and path validation.
# 
# Any maximum datagram size larger than 1200 bytes can be discovered
# using Path Maximum Transmission Unit Discovery (PMTUD) (see
# Section 14.2.1) or Datagram Packetization Layer PMTU Discovery
# (DPLPMTUD) (see Section 14.3).
# 
# Enforcement of the max_udp_payload_size transport parameter
# (Section 18.2) might act as an additional limit on the maximum
# datagram size.  A sender can avoid exceeding this limit, once the
# value is known.  However, prior to learning the value of the
# transport parameter, endpoints risk datagrams being lost if they send
# datagrams larger than the smallest allowed maximum datagram size of
# 1200 bytes.
# 
# UDP datagrams MUST NOT be fragmented at the IP layer.  In IPv4
# [IPv4], the Don't Fragment (DF) bit MUST be set if possible, to
# prevent fragmentation on the path.
# 
# QUIC sometimes requires datagrams to be no smaller than a certain
# size; see Section 8.1 as an example.  However, the size of a datagram
# is not authenticated.  That is, if an endpoint receives a datagram of
# a certain size, it cannot know that the sender sent the datagram at
# the same size.  Therefore, an endpoint MUST NOT close a connection
# when it receives a datagram that does not meet size constraints; the
# endpoint MAY discard such datagrams.

[[spec]]
level = "MUST"
quote = '''
QUIC MUST NOT be used if the network path cannot support a
maximum datagram size of at least 1200 bytes.
'''

[[spec]]
level = "MUST"
quote = '''
UDP datagrams MUST NOT be fragmented at the IP layer.
'''

[[spec]]
level = "MUST"
quote = '''
In IPv4
[IPv4], the Don't Fragment (DF) bit MUST be set if possible, to
prevent fragmentation on the path.
'''

[[spec]]
level = "MUST"
quote = '''
Therefore, an endpoint MUST NOT close a connection
when it receives a datagram that does not meet size constraints; the
endpoint MAY discard such datagrams.
'''