IBM 10 SP1 EAL4 manual Transport layer protocols, Network layer protocols

5.4.2Transport layer protocols

The transport layer protocols supported by the SLES kernel are TCP and UDP.

5.4.2.1TCP

TCP is a connection-oriented, end-to-end, reliable protocol designed to fit into a layered hierarchy of protocols that support multi-network applications. TCP provides for reliable IPC between pairs of processes in host computers attached to distinct but interconnected computer communication networks. TCP is used along with the Internet Protocol (IP) to send data in the form of message units between computers over the Internet. While IP takes care of handling the actual delivery of the data, TCP takes care of keeping track of the individual units of data, or packets, that a message is divided into for efficient routing through the Internet. For more information about TCP, refer to RFC 793.

5.4.2.2UDP

UDP is a connectionless protocol that, like TCP, runs on top of IP networks. UDP/IP provides very few error recovery services, offering instead a direct way to send and receive datagrams over an IP network. It is used primarily for broadcasting messages over a network. This protocol provides a procedure for application programs to send messages to other programs with a minimum of protocol mechanism. The protocol is transaction oriented, and delivery and duplicate protection are not guaranteed. For more information about UDP, look into RFC 768.

5.4.3Network layer protocols

The network layer protocols supported by the SLES kernel are IP and ICMP.

5.4.3.1Internet Protocol Version 4 (IPv4)

IPv4, aka simply IP, is the standard that defines the manner in which the network layers of two hosts interact. These hosts can be on the same network, or reside on physically distinct heterogeneous networks. In fact, IP was designed from the very beginning with inter-networking in mind.

IP provides a connectionless, unreliable, best-effort packet delivery service. Its service is called connectionless because in some ways it resembles the Postal Service. IP packets, like telegrams or mail messages, are treated independently. Each packet is stamped with the addresses of the receiver and the sender. Routing decisions are made on a packet-by-packet basis. IP is quite different from connection- oriented and circuit-switched phone systems that explicitly establish a connection between two users before any conversation, or data exchange, takes place, and maintain a connection for the entire length of exchange. For information about IP packets, IP addresses, and addressing formats refer to RFC 1883.

5.4.3.2Internet Protocol Version 6 (IPv6)

The SLES kernel supports Internet Protocol version 6. IPv6 is the standard that defines the manner in which network layers of two hosts interact, and is an increment to existing IPv4. The TOE is in compliance with IPv6 source address selection as documented in RFC 3484, and implements several new socket options (IPV6_RECVPKTINFO, IPV6_PKTINFO, IPV6_RECVHOPOPTS, IPV6_HOPOPTS, IPV6_RECVDSTOPTS, IPV6_DSTOPTS, IPV6_RTHDRDSTOPTS, IPV6_RECVRTHDR, IPV6_RTHDR, IPV6_RECVHOPOPTS, IPV6_HOPOPTS, IPV6_RECVTCLASS) and ancillary data in order to support advanced IPv6 applications including ping, traceroute, routing daemons and others.

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