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Chapter 34 Configuring Network Security with ACLs
Configuring IPv4 ACLs
Stack members perform these ACL functions:
• They receive the ACL information from the master switch and program their hardware.
• They act as standby switches, ready to take over the role of the stack master if the existing master
were to fail and they were to be elected as the new stack master.
When a stack master fails and a new stack master is elected, the newly elected master reparses the backed
up running configuration. (See Chapter 5, “Configuring the Switch Stack.”) The ACL configuration that
is part of the running configuration is also reparsed during this step. The new stack master distributes
the ACL information to all switches in the stack.
Configuring IPv4 ACLs
Configuring IP v4ACLs on the switch is the same as configuring IPv4 ACLs on other Cisco switches and
routers. The process is briefly described here. For more detailed information on configuring ACLs, see
the “Configuring IP Services” section in the “IP Addressing and Services” chapter of the Cisco IOS IP
Configuration Guide, Release 12.2. For detailed information about the commands, see the Cisco IOS IP
Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2.
The switch does not support these Cisco IOS router ACL-related features:
• Non-IP protocol ACLs (see Table 34-1 on page 34-8) or bridge-group ACLs
• IP accounting
• Inbound and outbound rate limiting (except with QoS ACLs)
• Reflexive ACLs or dynamic ACLs
• ACL logging for port ACLs and VLAN maps
These are the steps to use IP ACLs on the switch:
Step 1 Create an ACL by specifying an access list number or name and the access conditions.
Step 2 Apply the ACL to interfaces or terminal lines. You can also apply standard and extended IP ACLs to
VLAN maps.
These sections contain this configuration information:
• Creating Standard and Extended IPv4 ACLs, page 34-7
• Applying an IPv4 ACL to a Terminal Line, page 34-19
• Applying an IPv4 ACL to an Interface, page 34-20
• Hardware and Software Treatment of IP ACLs, page 34-22
• IPv4 ACL Configuration Examples, page 34-22
Creating Standard and Extended IPv4 ACLs
This section describes IP ACLs. An ACL is a sequential collection of permit and deny conditions. One
by one, the switch tests packets against the conditions in an access list. The first match determines
whether the switch accepts or rejects the packet. Because the switch stops testing after the first match,
the order of the conditions is critical. If no conditions match, the switch denies the packet.
