Connection-rate Access Control Lists (ACLs)

The basic connection-rate filtering policy is configured per-port as notify-only, throttle, and block. A connection-rate ACL creates exceptions to these per-port policies by creating special rules for individual hosts, groups of hosts, or entire subnets. Thus, you can adjust a connection-rate filtering policy to create and apply an exception to configured filters on the ports in a VLAN. Note that connection-rate ACLs are useful only if you need to exclude inbound traffic from your connection-rate filtering policy. For example, a server responding to network demand can send a relatively high number of legitimate connection requests. This can generate a false positive by exhibiting the same elevated connection-rate behavior as a worm. Using a connection-rate ACL to apply an exception for this server allows you to exclude the trusted server from connection-rate filtering and thereby keep the server running without interruption.


Use connection-rate ACLs only when you need to exclude an IP traffic source (including traffic with specific UDP or TCP criteria) from a connection-rate filtering policy. Otherwise, the ACL is not necessary.