Troubleshooting Acls; Ipv4 Acl Configuration Examples - Cisco Catalyst 2928 Software Configuration Manual

Configuring IPv4 ACLs

Troubleshooting ACLs

If this ACL manager message appears and [chars] is the access-list name,
ACLMGR-2-NOVMR: Cannot generate hardware representation of access list [chars]
The switch has insufficient resources to create a hardware representation of the ACL. The resources
include hardware memory and label space but not CPU memory. A lack of available logical operation
units or specialized hardware resources causes this problem. Logical operation units are needed for a
TCP flag match or a test other than eq (ne, gt, lt, or range) on TCP, UDP, or SCTP port numbers.
Use one of these workarounds:
•
•
To determine the specialized hardware resources, enter the show platform layer4 acl map privileged
EXEC command. If the switch does not have available resources, the output shows that index 0 to
index 15 are not available.
For more information about configuring ACLs with insufficient resources, see CSCsq63926 in the Bug
Toolkit.
For example, if you apply this ACL to a VLAN interface:
permit tcp source source-wildcard destination destination-wildcard range 5 60
permit tcp source source-wildcard destination destination-wildcard range 15 160
permit tcp source source-wildcard destination destination-wildcard range 115 1660
permit tcp source source-wildcard destination destination-wildcard
And if this message appears:
ACLMGR-2-NOVMR: Cannot generate hardware representation of access list [chars]
The flag-related operators are not available. To avoid this issue,
•
•
You can now apply the first ACE in the ACL to the VLAN interface. The switch allocates the ACE to
available mapping bits in the Opselect index and then allocates flag-related operators to use the same
bits in the TCAM.

IPv4 ACL Configuration Examples

This section provides examples of configuring and applying IPv4 ACLs. For detailed information about
compiling ACLs, see the Cisco IOS Security Configuration Guide, Release 12.2 and to the Configuring
IP Services" section in the "IP Addressing and Services" chapter of the Cisco IOS IP Configuration
Guide, Release 12.2.
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30-18
Modify the ACL configuration to use fewer resources.
Rename the ACL with a name or number that alphanumerically precedes the ACL names or
numbers.
Move the fourth ACE before the first ACE by using ip access-list resequence global configuration
command:
permit tcp source source-wildcard destination destination-wildcard
permit tcp source source-wildcard destination destination-wildcard range 5 60
permit tcp source source-wildcard destination destination-wildcard range 15 160
permit tcp source source-wildcard destination destination-wildcard range 115 1660
or
Rename the ACL with a name or number that alphanumerically precedes the other ACLs (for
example, rename ACL 79 to ACL 1).
Chapter 30 Configuring Network Security with ACLs
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