Operating Systems

The 10 Commandments of TCP/IP Performance

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7.       Thou shalt delve deeply into User Datagram Protocol (UDP) No Ports errors: The UDP

equivalent of TCP Attempts Failed is UDP No Ports. These counters may appear in the output of the Netstat STATS command or you may see them while interrogating the SNMP MIB. UDP No Ports means some packets were sent for a UDP port that wasn’t available. It may be there’s a UDP application that isn’t active. If all UDP sockets are active, then it may be that UDP traffic is coming in at too high a rate for a particular port. We’ve seen this error to be correlated with ICMP Destination Unreachable Sub Type Port Unreachable error.

The ICMP Destination Unreachable message has several subtypes that indicate the type of error. These subtypes are as follows:

0 = Network Unreachable

1 = Host Unreachable

2 = Protocol Unreachable

3 = Port Unreachable

4 = Fragmentation Needed But Do Not Fragment Set

6 Pages