Administrator Guide

Determine the Order in which ACLs are Used to Classify Traffic
When you link class-maps to queues using the service-queue command, Dell EMC 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 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 EMC 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 order Keyword to Determine ACL Sequence
DellEMC(conf)#ip access-list standard acl1
DellEMC(config-std-nacl)#permit 20.0.0.0/8
DellEMC(config-std-nacl)#exit
DellEMC(conf)#ip access-list standard acl2
DellEMC(config-std-nacl)#permit 20.1.1.0/24 order 0
DellEMC(config-std-nacl)#exit
DellEMC(conf)#class-map match-all cmap1
DellEMC(conf-class-map)#match ip access-group acl1
DellEMC(conf-class-map)#exit
DellEMC(conf)#class-map match-all cmap2
DellEMC(conf-class-map)#match ip access-group acl2
DellEMC(conf-class-map)#exit
DellEMC(conf)#policy-map-input pmap
DellEMC(conf-policy-map-in)#service-queue 7 class-map cmap1
DellEMC(conf-policy-map-in)#service-queue 4 class-map cmap2
DellEMC(conf-policy-map-in)#exit
DellEMC(conf)#interface te 10/1
DellEMC(conf-if-te-10/1)#service-policy input pmap
Important Points to Remember
• For route-maps with more than one match clause:
• Two or more match clauses within the same route-map sequence have the same match commands (though the values are
different), matching a packet against these clauses is a logical OR operation.
• Two or more match clauses within the same route-map sequence have different match commands, matching a packet against
these clauses is a logical AND operation.
• If no match is found in a route-map sequence, the process moves to the next route-map sequence until a match is found, or there are
no more sequences.
• When a match is found, the packet is forwarded and no more route-map sequences are processed.
• If a continue clause is included in the route-map sequence, the next or a specified route-map sequence is processed after a match
is found.
Configuration Task List for Route Maps
Configure route maps in ROUTE-MAP mode and apply the maps in various commands in ROUTER RIP and ROUTER OSPF modes.
The following list includes the configuration tasks for route maps, as described in the following sections.
• Create a route map (mandatory)
• Configure route map filters (optional)
• Configure a route map for route redistribution (optional)
• Configure a route map for route tagging (optional)
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Access Control Lists (ACLs)