Outgoing routed IPv4 packets are filtered by the router ACL. When an output router ACL and input port ACL exist in an SVI, incoming packets received on the ports to which a port ACL is applied are filtered by the port ACL.Incoming routed IPv4 packets received on other ports are filtered by the router ACL. When an input router ACL and input port ACL exist in an switch virtual interface (SVI), incoming packets received on ports to which a port ACL is applied are filtered by the port ACL.Other packets are filtered by the VLAN map When both an input port ACL and a VLAN map are applied, incoming packets received on ports with a port ACL applied are filtered by the port ACL.However, a port ACL takes precedence over a router ACL or VLAN map. You can use input port ACLs, router ACLs, and VLAN maps on the same switch. Packets can either enter the VLAN through a switch port or through a routed port after being routed. After a VLAN map is applied to a VLAN, all packets entering the VLAN are checked against the VLAN map. Unsupported protocols are access-controlled through MAC addresses using Ethernet ACEs. VLAN maps are configured to provide access control based on Layer 3 addresses for IPv4. You can use VLAN maps to filter traffic between devices in the same VLAN. VLAN ACLs or VLAN maps access-control all packets (forwarded and routed).The switch must be running the metro IP access image to support router ACLs. Router ACLs access-control routed traffic between VLANs and are applied to Layer 3 interfaces in a specific direction (inbound or outbound).Note Port ACLs are not supported on ports configured with service instances. IP ACLs filter IPv4 traffic, including TCP, User Datagram Protocol (UDP), Internet Group Management Protocol (IGMP), and Internet Control Message Protocol (ICMP). The switch supports IPv4 ACLs and Ethernet (MAC) ACLs: The meaning of permit or deny depends on the context in which the ACL is used. Each ACE specifies permit or deny and a set of conditions the packet must satisfy in order to match the ACE. ACLs can be configured to block inbound traffic, outbound traffic, or both.Īn ACL contains an ordered list of access control entries (ACEs). For example, you can allow e-mail traffic to be forwarded but not Telnet traffic. You can use ACLs to control which hosts can access different parts of a network or to decide which types of traffic are forwarded or blocked at router interfaces. If you do not configure ACLs, all packets passing through the switch could be allowed onto all parts of the network. You configure access lists on a router or Layer 3 switch to provide basic security for your network. The switch can use ACLs on all packets it forwards. If there are no restrictions, the switch forwards the packet otherwise, the switch drops the packet. If no conditions match, the switch rejects the packet. Because the switch stops testing after the first match, the order of conditions in the list is critical. The first match decides whether the switch accepts or rejects the packets. One by one, it tests packets against the conditions in an access list. When a packet is received on an interface, the switch compares the fields in the packet against any applied ACLs to verify that the packet has the required permissions to be forwarded, based on the criteria specified in the access lists. An ACL is a sequential collection of permit and deny conditions that apply to packets. ACLs filter traffic as it passes through a router or switch and permit or deny packets crossing specified interfaces or VLANs. Packet filtering can help limit network traffic and restrict network use by certain users or devices. See the "Ingress Classification Based on QoS ACLs" section. Note Not all ACL parameters can be used for QoS classification. Information in this chapter about IP ACLs is specific to IP Version 4 (IPv4). This chapter describes how to configure network security on the Cisco ME 3800X and 3600X switch by using access control lists (ACLs), which are also referred to in commands and tables as access lists. VLAN Maps and Router ACL Configuration GuidelinesĮxamples of Router ACLs and VLAN Maps Applied to VLANs Hardware and Software Treatment of IP ACLsĪpplying a MAC ACL to a Layer 2 Interfaceĭenying Access to a Server on Another VLAN Handling Fragmented and Unfragmented TrafficĬreating Named Standard and Extended ACLs
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