1·The receiving host is on the same subnet as the sending host, in which case the datagram will be sent directly from the sender to the receiver.
接收主机和发送主机位于同一子网，这种情况下数据报将被直接从发送方发送到接收方。
2·Internet Protocol (IP) provides a host-to-host packet — or datagram — delivery service.
网际协议(IP)提供“主机对主机”包(或数据报)传递服务。
3·IP provides the most basic form of datagram delivery across the boundaries of the underlying physical networks.
IP在底层物理网络的边界之间提供最基本的数据报传递形式。
4·UDP packet or user datagram: UDP is an unreliable, connectionless protocol.
UD p包或用户数据报：udp是不可靠、无连接的协议。
5·Plain IP packet, or IP datagram: IP packets are used to encapsulate any of the following protocols.
普通 IP 包或IP 数据报：IP 包可用来封装以下任何协议。