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Catalyst 6000 Family Software Configuration Guide—Releases 6.3 and 6.4
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Chapter 16 Configuring Access Control
Using Cisco IOS ACLs in your Network
Policy Routing
Policy routing-required flows are handled in the software without impacting non-policy routed flow
forwarding in the hardware. When a route map contains multiple “match” clauses, all conditions
imposed by these match clauses must be met before a packet is policy routed. However, for route maps
containing both “match ip address” and “match length,” all traffic matching the ACL in the “match ip
address” clause is forwarded to the software regardless of the match length criteria. For route maps that
only contain match length clauses, all packets received on the interface are forwarded to the software.
When you enable hardware policy routing using the
mls ip pbr
global command, all policy routing
occurs in the hardware.
Caution
If you use the
mls ip pbr
command to enable policy routing, policy routing is applied in the hardware
for all interfaces regardless of which interface was configured for policy routing.
WCCP
HTTP requests subject to Web Cache Coordination Protocol (WCCP) redirection are handled in the
software; HTTP replies from the server and the Cache Engine are handled in the hardware.
NAT
NAT-required flows are handled in the software without impacting non-NAT flow forwarding in the
hardware.
Unicast RPF Check
The unicast RPF feature is supported in hardware on the PFC. For ACL-based RPF checks, traffic denied
by the unicast RPF ACL is forwarded to the MSFC for RPF validation.
Caution
With ACL-based unicast RPF, packets denied by the ACL are sent to the CPU for RPF validation. In the
event of DOS attacks, these packets will most likely match the deny ACE and be forwarded to the CPU.
Under heavy traffic conditions, this could cause high CPU utilization.
Note
Drop-suppress statistics for ACL-based RPF check is not supported.
Bridge-Groups
Cisco IOS bridge-group ACLs are handled in the software.
Hardware and Software Handling of Cisco IOS ACLs with PFC2
This section describes hardware and software handling of Cisco IOS ACLs with the PFC2.