Why is SNMP usually run over UDP and not TCP/IP?

Question

This morning, there were big problems at work because an SNMP trap didn\'t \"go through\" because SNMP is run over UDP. I remember from the networking class in college that

Answer 1

If systems sent SNMP traps via TCP they could block waiting for the packets to be ACKed if there was a problem getting the traffic to the receiver. If a lot of traps were generated, it could use up the available sockets on the system and the system would lock up. With UDP that is not an issue because it is stateless. A similar problem took out BitBucket in January although it was syslog protocol rather than SNMP--basically, they were inadvertently using syslog over TCP due to a configuration error, the syslog server went down, and all of the servers locked up waiting for the syslog server to ACK their packets. If SNMP traps were sent over TCP, a similar problem could occur.

http://blog.bitbucket.org/2012/01/12/follow-up-on-our-downtime-last-week/