IPv4 ACLs

IPv4 ACLs permit or deny IPv4 packets according to rules included in the ACLs.

Regarding the range of filtering options, there are two types of IPv4 ACLs:

  • Standard ACLs: Permit or deny traffic according to source address only.
  • Extended ACLs: Permit or deny traffic according to source and destination addresses, as well as other parameters. For example, in an extended ACL, you can also filter by one or more of the following parameters:
    • Port name or number
    • Protocol (for example, TCP or UDP)
    • TCP flags

The following points apply to named ACLs:

  • An ACL name cannot begin with numbers or underscore.
  • Double quotes usage is permitted solely for enclosing names that contain spaces. If the name contains spaces, put it within quotation marks.
  • All other special characters are allowed.

In this section:

  1. IPv4 ACL Configuration Guidelines
  2. Creating and Applying a Standard IPv4 ACL
    A standard ACL permits or denies traffic according to source address only.
  3. IPv4 Extended ACL Traffic Filtering Criteria
  4. Creating and Applying an Extended IPv4 ACL
  5. Applying Egress ACLs to Control (CPU) Traffic
  6. Preserving User Input for ACL TCP/UDP Port Numbers
    ACL implementations automatically display the TCP/UDP port name instead of the port number, regardless of user preference, unless the device is configured to preserve user input. When the option to preserve user input is enabled, the system displays either the port name or the number.
  7. Enabling Strict Control of ACL Filtering of Fragmented Packets
  8. Filtering on IP Precedence and ToS Values
    The following example configures an extended IP ACL that matches based on IP precedence.
  9. ACLs to Filter ARP Packets
  10. QoS Options for IP ACLs
    ACL Quality of Service (QoS) parameters enable you to perform QoS for packets that match the ACLs.
  11. ACL-based Rate Limiting
    ACL-based rate limiting provides the facility to limit the rate for inbound IP traffic that matches the permit conditions in extended IP ACLs. ACL-based rate limiting is available in the Layer 2 and Layer 3 code.
  12. ACLs to Control Multicast Features
  13. Displaying IPv4 ACL Information
Parent topic: ACLs