Reference Guide

To allocate the number of FP blocks for ACL VLAN optimization, enter the cam-acl-vlan vlanaclopt
<0-2> command. After you configure ACL VLAN CAM, reboot the switch to enable CAM allocation for
ACL VLAN optimization.
To display the number of FP blocks currently allocated to different ACL VLAN services, enter the show
cam-acl-vlan command.
To display the amount of CAM space currently used and available for Layer 2 and Layer 3 ACLs on the
switch, enter the show cam-usage command.
Implementing ACLs on Dell Networking OS
You can assign one IP ACL per interface. If you do not assign an IP ACL to an interface, it is not used by
the software.
The number of entries allowed per ACL is hardware-dependent.
If counters are enabled on ACL rules that are already configured, those counters are reset when a new
rule which is inserted or prepended or appended requires a hardware shift in the flow table. Resetting the
counters to 0 is transient as the proginal counter values are retained after a few seconds. If there is no
need to shift the flow in the hardware, the counters are not affected. This is applicable to the following
features:
• L2 Ingress Access list
• L2 Egress Access list
NOTE: IP ACLs are supported over VLANs in Dell Networking OS version 6.2.1.1 and higher.
Assigning ACLs to VLANs
When you apply an ACL to a VLAN using single port-pipe, a copy of the ACL entries gets installed in the
ACL CAM on the port-pipe. The entry looks for the incoming VLAN in the packet. When you apply an ACL
on individual ports of a VLAN, separate copies of the ACL entries are installed for each port belonging to a
port-pipe.
You can use the log keyword to log the details about the packets that match. The control processor
becomes busy based on the number of packets that match the log entry and the rate at which the details
are logged in. However, the route processor (RP) is unaffected. You can use this option for debugging
issues related to control traffic.
ACL Optimization
If an access list contains duplicate entries, Dell Networking OS deletes one entry to conserve CAM space.
Standard and extended ACLs take up the same amount of CAM space. A single ACL rule uses two CAM
entries to identify whether the access list is a standard or extended ACL.
Determine the Order in which ACLs are Used to Classify Traffic
When you link class-maps to queues using the service-queue command, Dell Networking OS matches
the class-maps according to queue priority (queue numbers closer to 0 have lower priorities).
As shown in the following example, class-map cmap2 is matched against ingress packets before cmap1.
ACLs acl1 and acl2 have overlapping rules because the address range 20.1.1.0/24 is within 20.0.0.0/8.
Therefore (without the keyword order), packets within the range 20.1.1.0/24 match positive against
Access Control Lists (ACLs)
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