This is retired content. This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This content may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.
A version of this page is also available for

IP is the mailroom of the TCP/IP stack, where packet sorting and delivery take place. At this layer, each incoming or outgoing packet is referred to as a datagram. Each IP datagram bears the source IP address of the sender and the destination IP address of the intended recipient. Unlike the MAC addresses, the IP addresses in a datagram remain the same throughout a packet's journey across an inter-network. IP layer functions are described below.

IP is central to the TCP/IP stack — all other TCP/IP protocols use IP — and all data passes through it. IP is a connectionless protocol and has some limitations. If IP attempts packet delivery and in the process a packet is lost, delivered out of sequence, duplicated, or delayed, neither sender nor receiver is informed. Packet acknowledgement is handled by a higher-layer transport protocol, such as TCP.

IP is responsible for addressing and routing packets between hosts, and for fragmentation. Fragmentation is the process of breaking a datagram into smaller pieces for inter-network routing. IP fragments packets prior to sending them and reassembles them upon receipt.

Winsock applications can send packets, but cannot affect packet routing or fragmentation.

Windows CE .NET 4.1 and later provides a dual protocol stack to support 32-bit IPv4 addresses and 128-bit IPv6 addresses. For information about the stack architecture, see Dual Stack Architecture.

The following table shows links to information about IPv6.

Area IPv6 topics

Addressing, name registration and name resolution

Configuring addresses


Subnet multicasting

See Also