UDP (2024)

User Datagram Protocol (UDP) (RFC 768) is another main protocolof the IP suite, and is an alternative to TCP. UDP is statelessand connectionless in that there is no handshake to set up a session,and no connection between the sender and receiver; the packets maytake different routes to get to a single destination. UDP is consideredan unreliable protocol because it does not provide acknowledgments,error-checking, retransmission, or reordering of datagrams. Withoutthe overhead required to provide those features, UDP has reducedlatency and is faster than TCP. UDP is referred to as a best-effortprotocol because there is no mechanism or guarantee to ensure thatthe data will arrive at its destination.

A UDP datagram is encapsulated in an IP packet. Although UDPuses a checksum for data integrity, it performs no error checkingat the network interface level. Error checking is assumed to beunnecessary or is performed by the application rather than UDP itself.UDP has no mechanism to handle flow control of packets.

UDP is often used for applications that require faster speedsand time-sensitive, real-time delivery, such as Voice over IP (VoIP),streaming audio and video, and online games. UDP is transaction-oriented,so it is also used for applications that respond to small queriesfrom many clients, such as Domain Name System (DNS) and TrivialFile Transfer Protocol (TFTP).

You can use Zone Protection Profiles onthe firewall to configure flood protection and thereby specify therate of UDP connections per second (not matching an existing session)that trigger an alarm, trigger the firewall to randomly drop UDPpackets, and cause the firewall to drop UDP packets that exceedthe maximum rate. (Although UDP is connectionless, the firewalltracks UDP datagrams in IP packets on a session basis; thereforeif the UDP packet doesn’t match an existing session, it is considereda new session and it counts as a connection toward the thresholds.)

{{ } }} {{ } else { }}