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Catalyst 3750 SwitchSoftware Configuration Guide
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Chapter34 Configuring Network Security with ACLs
Configuring IPv4 ACLs
If packets must be forwarded by software for any reason (for example, not enough hardware
resources), the master switch forwards the packets only after applying ACLs on the packets.
It programs its hardware with the ACL information it processes.
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 Cisco IOS
documentation is available from the Cisco.com page under Documentation > Cisco IOS Software >
12.2 Mainline > Configuration Guides or Command References.
The switch does not support these Cisco IOS router ACL-related features:
Non-IP protocol ACLs (see Table34-1 on page 34-8) or bridge-group ACLs
IP accounting
Inbound and outbound rate limiting (except with QoS ACLs)
Reflexive ACLs or dynamic ACLs (except for some specialized dynamic ACLs used by the switch
clustering feature)
ACL logging for port ACLs and VLAN maps
These are the steps to use IP ACLs on the switch:
Step1 Create an ACL by specifying an access list number or name and the access conditions.
Step2 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, page34-8
Applying an IPv4 ACL to a Terminal Line, page34-20
Applying an IPv4 ACL to an Interface, page34-20
Hardware and Software Treatment of IP ACLs, page 34-22
Troubleshooting ACLs, page34-22
IPv4 ACL Configuration Examples, page34-23