Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 110

Example of Viewing Filter Sequence for a Specified Extended ACL Dell(config-ext-nacl)#deny tcp host 123.55.34.0 any Dell(config-ext-nacl)#permit udp 154.44.123.34 0.0.255.255 host 34.6.0.0 Dell(config-ext-nacl)#show config ! ip access-list extended nimule seq 5 deny tcp host 123.55.34.0 any seq 10 permit udp 154.44.0.0 0.0.255.255 host 34.6.0.0 Dell(config-ext-nacl)# To view all configured IP ACLs and the number of packets processed through the ACL, use the show ip accounting access-list command in EXEC Privilege mode, as shown in the first example in Configure a Standard IP ACL Filter. Configure Layer 2 and Layer 3 ACLs Both Layer 2 and Layer 3 ACLs may be configured on an interface in Layer 2 mode. If both L2 and L3 ACLs are applied to an interface, the following rules apply: • When Dell Networking OS routes the packets, only the L3 ACL governs them because they are not filtered against an L2 ACL. • When Dell Networking OS switches the packets, first the L3 ACL filters them, then the L2 ACL filters them. • When Dell Networking OS switches the packets, the egress L3 ACL does not filter the packet. For the following features, if you enable counters on rules that have already been configured and a new rule is either inserted or prepended, all the existing counters are reset: • L2 ingress access list • L3 egress access list • L2 egress access list If a rule is simply appended, existing counters are not affected. Table 6. L2 and L3 Filtering on Switched Packets L2 ACL Behavior L3 ACL Behavior Deny Deny Deny Permit Permit Deny Permit Permit Decision on Targeted Traffic L3 ACL denies. L3 ACL permits. L3 ACL denies. L3 ACL permits. NOTE: If you configure an interface as a vlan-stack access port, only the L2 ACL filters the packets. The L3 ACL applied to such a port does not affect traffic. That is, existing rules for other features (such as trace-list, policy-based routing [PBR], and QoS) are applied to the permitted traffic. For information about MAC ACLs, refer to Layer 2. Assign an IP ACL to an Interface To pass traffic through a configured IP ACL, assign that ACL to a physical interface, a port channel interface, or a VLAN. The IP ACL is applied to all traffic entering a physical or port channel interface and the traffic is either forwarded or dropped depending on the criteria and actions specified in the ACL. The same ACL may be applied to different interfaces and that changes its functionality. For example, you can take ACL "ABCD" and apply it using the in keyword and it becomes an ingress access list. If you apply the same ACL using the out keyword, it becomes an egress access list. If you apply the same ACL to the Loopback interface, it becomes a Loopback access list. This section describes the following: • Configure Ingress ACLs 110 Access Control Lists (ACLs)