Dell Force10 Z9000 Configuration Manual page 87

• 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.
ACLs and VLANs
There are some differences when assigning ACLs to a VLAN rather than a physical port.
For example, when using a single port-pipe, if you apply an ACL to a VLAN, one copy of the ACL entries is installed in the ACL CAM
on the port-pipe. The entry looks for the incoming VLAN in the packet. Whereas if 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.
When you use the log keyword, the CP has to log the details about the packets that match. Depending on how many packets
match the log entry and at what rate, the CP might become busy as it has to log these packets' details. However, the other
processors (RP1 and RP2) are unaffected. This option is typically useful when debugging some problem related to control traffic. We
have used this option numerous times in the field and have not encountered problems so far.
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 whether it is
identified as 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 cmap1 and are buffered in queue 7, though you intended
for these packets to match positive against cmap2 and be buffered in queue 4.
In cases such as these, where class-maps with overlapping ACL rules are applied to different queues, use the order keyword to
specify the order in which you want to apply ACL rules. The order can range from 0 to 254. Dell Networking OS writes to the CAM
ACL rules with lower-order numbers (order numbers closer to 0) before rules with higher-order numbers so that packets are
matched as you intended. By default, all ACL rules have an order of 255.
Example of the Keyword to Determine ACL Sequence
order
Dell(conf)#ip access-list standard acl1
Dell(config-std-nacl)#permit 20.0.0.0/8
Dell(config-std-nacl)#exit
Dell(conf)#ip access-list standard acl2
Dell(config-std-nacl)#permit 20.1.1.0/24 order 0
Dell(config-std-nacl)#exit
Dell(conf)#class-map match-all cmap1
Dell(conf-class-map)#match ip access-group acl1
Dell(conf-class-map)#exit
Dell(conf)#class-map match-all cmap2
Dell(conf-class-map)#match ip access-group acl2
Dell(conf-class-map)#exit
Dell(conf)#policy-map-input pmap
Dell(conf-policy-map-in)#service-queue 7 class-map cmap1
Dell(conf-policy-map-in)#service-queue 4 class-map cmap2
Dell(conf-policy-map-in)#exit
Dell(conf)#interface te 10/1
Dell(conf-if-te-10/1)#service-policy input pmap
Access Control Lists (ACLs)
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