Techninal Gyaan in Hindi: CCNA in Hindi

What does a router do? It receives traffic on one interface, checks its routing table for the destination network in the packet, and if a route exists, forwards the packet through the outgoing interface present in the route.

A router drops a packet, only if it doesn't find a route for the destination in it's routing table. What if we want the router to drop some packets for us? We can do so by specifying criteria to select packets to drop, by using Access Control Lists or ACL. To filter IP traffic we use IP ACL.

An ACL is a list of rules defined by the administrator that specifies what kind of traffic is permitted through the router. The criteria to select packets can be based on Source and/or Destination IP address, protocol and source and/or destination port nos.

Following six part video series explains various kinds of IP ACLs and their configuration on CISCO routers;

CCNA Hindi - IP Access Control List Part 1