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Configuring ACLs
Unless otherwise stated, ACLs refer to both IPv4 and IPv6 ACLs throughout this document.
Overview
An access control list (ACL) is a set of rules (or permit or deny statements) for identifying traffic
based on criteria such as source IP address, destination IP address, and port number.
ACLs are primarily used for packet filtering. A packet filter drops packets that match a deny rule and
permits packets that match a permit rule. ACLs are also used by many modules, QoS and IP routing
for example, for traffic classification and identification.
Applications on the switch
An ACL is implemented in hardware or software, depending on the module that uses it. If the module,
the packet filter or QoS module for example, is implemented in hardware, the ACL is applied to
hardware to process traffic. If the module, the routing or user interface access control module (Telnet,
SNMP, or web) for example, is implemented in software, the ACL is applied to software to process
traffic.
The user interface access control module denies packets that do not match any ACL. Some modules,
QoS for example, ignore the permit or deny action in ACL rules and do not base their drop or
forwarding decisions on the action set in ACL rules. See the specified module for information about
ACL application.
ACL categories
Category
Basic ACLs
Advanced ACLs
Ethernet frame
header ACLs
Numbering and naming ACLs
Each ACL category has a unique range of ACL numbers. When creating an ACL, you must assign it
a number. In addition, you can assign the ACL a name for ease of identification. After creating an
ACL with a name, you cannot rename it or delete its name.
For an Ethernet frame header ACL, the ACL number and name must be globally unique. For an IPv4
basic or advanced ACLs, its ACL number and name must be unique among all IPv4 ACLs, and for an
ACL
IP version
number
IPv4
2000 to 2999
IPv6
IPv4
3000 to 3999
IPv6
IPv4 and
4000 to 4999
IPv6
Match criteria
Source IPv4 address
Source IPv6 address
Source IPv4 address, destination IPv4 address, packet
priority, protocols over IPv4, and other Layer 3 and Layer
4 header fields
Source IPv6 address, destination IPv6 address, packet
priority, protocols over IPv6, and other Layer 3 and Layer
4 header fields
Layer 2 header fields, such as source and destination
MAC addresses, 802.1p priority, and link layer protocol
type
1
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