ACL Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-14 Static Port ACL and Dynamic Port ACL Applications . . . . . . . . . 9-15 Dynamic (RADIUS-assigned) Port ACL Applications . . . . . . . . . 9-15 Multiple ACLs on an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-16 Features Common to All ACL Applications . . . . . . . . . . . . . . . . . . . . . 9-16 General Steps for Planning and Configuring ACLs . . . . . . . . . . . . . . . 9-18

IPv4 Static ACL Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20

The Packet-filtering Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-20

Planning an ACL Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-24

IPv4 Traffic Management and Improved Network Performance

. . . 9-24

Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-25

Guidelines for Planning the Structure of a Static ACL . . . . . . . . .

. . . 9-26

IPv4 ACL Configuration and Operating Rules . . . . . . . . . . . . . . . .

. . . 9-27

How an ACE Uses a Mask To Screen Packets for Matches . . . . .

. . . 9-28

What Is the Difference Between Network (or Subnet)

 

Masks and the Masks Used with ACLs? . . . . . . . . . . . . . . . . .

. . . 9-28

Rules for Defining a Match Between a Packet and an

 

Access Control Entry (ACE) . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-29

Configuring and Assigning an IPv4 ACL . . . . . . . . . . . . . . . . . . . .

. . . 9-34

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-34

General Steps for Implementing ACLs . . . . . . . . . . . . . . . . . .

. . . 9-34

Options for Permit/Deny Policies . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-35

ACL Configuration Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-35

Standard ACL Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-36

Extended ACL Configuration Structure . . . . . . . . . . . . . . . . .

. . . 9-37

ACL Configuration Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-39

The Sequence of Entries in an ACL Is Significant . . . . . . . . .

. . . 9-39

Allowing for the Implied Deny Function . . . . . . . . . . . . . . . . .

. . . 9-41

A Configured ACL Has No Effect Until You Apply It

 

to an Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . 9-41

You Can Assign an ACL Name or Number to an Interface

Even if the ACL Does Not Exist in the Switch’s Configuration . 9-41

Using the CLI To Create an ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9-42

General ACE Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9-42

Using CIDR Notation To Enter the IPv4 ACL Mask . . . . . . . . . .

9-43

xi