Table of Contents
Advertisement
Configuring ACLs
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 traffic identification. The packet drop or forwarding decisions varies with
the modules that use ACLs.
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. 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 IPv4 basic or advanced ACLs, its ACL number and name must be unique in IPv4, and for an
IPv6 basic or advanced ACL, its ACL number and name must be unique in IPv6.
Match order
The rules in an ACL are sorted in a specific order. When a packet matches a rule, the device stops
the match process and performs the action defined in the rule. If an ACL contains overlapping or
conflicting rules, the matching result and action to take depend on the rule order.
The following ACL match orders are available:
•
config—Sorts ACL rules in ascending order of rule ID. A rule with a lower ID is matched before
a rule with a higher ID. If you use this method, check the rules and their order carefully.
•
auto—Sorts ACL rules in depth-first order. Depth-first ordering makes sure that any subset of a
rule is always matched before the rule.
ordering uses to sort rules for each type of ACL.
ACL number
IP version
IPv4
2000 to 2999
IPv6
IPv4
3000 to 3999
IPv6
4000 to 4999
N/A
Match criteria
Source IPv4 address
Source IPv6 address
Source IPv4 address, destination IPv4
address, packet priority, protocol number, and
other Layer 3 and Layer 4 header fields
Source IPv6 address, destination IPv6
address, packet priority, protocol number, 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
Table 1
lists the sequence of tie breakers that depth-first
1
Advertisement
Table of Contents
