IP SANs: A Guide to iSCSI, iFCP, and FCIP Protocols for Storage Area Networks

6.2. Chapter Summary

Layer 4—UDP

• UDP is a streamlined transport layer protocol.

• UDP incurs minimal CPU overhead and offers higher performance.

Connectionless Service

• UDP requires no session establishment prior to data transmission.

• Delivery of UDP datagrams is unacknowledged by the recipient.

• Lack of flow control makes UDP dependent on link-layer services such as 802.3x.

• UDP with 802.3x flow control is analogous to class 3 Fibre Channel service.

• In the event of packet loss, upper layer applications must recover or retransmit.

UDP Port Numbers

• UDP provides identifying port numbers that associate transactions with specific upper layer applications.

• Port numbers for both UDP and TCP are 16-bit integers.

• Assignment of port numbers also enables concurrent ...