Access Control Lists (ACLs) are network filters used by routers and some switches to permit and restrict data flows in and out of network devices. When an ACL is implemented in a device or interface, the network device analyses data passing through it, compares it to the specification described in the ACL, and allows it the data to flow or prohibits it. One of the main reasons ACLs arre used is to provide a basic level of security for networks. If anything, the use of ACLs and their complexities bring about a delay in transmission through networks.
