Cisco Catalyst 2960 Series, Configuration Manual

Page: 1301 / 2288

Information About Configuring IPv6 ACLs
You can filter IP version 6 (IPv6) traffic by creating IPv6 access control lists (ACLs) and applying them to
interfaces similarly to the way that you create and apply IP version 4(IPv4) named ACLs. You can also create
and apply input router ACLs to filter Layer 3 management traffic.
To use IPv6, you must configure the dual IPv4 and IPv6 Switch Database Management (SDM) template
on the switch. You select the template by entering the
sdm prefer {default | dual-ipv4-and-ipv6} global
configuration command.
Note
ACL Overview
Packet filtering can help limit network traffic and restrict network use by certain users or devices. ACLs filter
traffic as it passes through a router or switch and permit or deny packets crossing specified interfaces or
VLANs. An ACL is a sequential collection of permit and deny conditions that apply to packets. 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.
One by one, it tests packets against the conditions in an access list. The first match decides whether the switch
accepts or rejects the packets. Because the switch stops testing after the first match, the order of conditions
in the list is critical. If no conditions match, the switch rejects the packet. If there are no restrictions, the switch
forwards the packet; otherwise, the switch drops the packet. The switch can use ACLs on all packets it forwards,
including packets bridged within a VLAN.
You configure access lists on a router or Layer 3 switch to provide basic security for your network. If you do
not configure ACLs, all packets passing through the switch could be allowed onto all parts of the network.
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. For example, you can allow e-mail traffic to be forwarded
but not Telnet traffic. ACLs can be configured to block inbound traffic, outbound traffic, or both.
IPv6 ACLs Overview
You can filter IP Version 6 (IPv6) traffic by creating IPv6 access control lists (ACLs) and applying them to
interfaces similarly to the way that you create and apply IP Version 4 (IPv4) named ACLs. You can also
create and apply input router ACLs to filter Layer 3 management traffic when the switch is running the IP
base and LAN base feature sets.
A switch supports two types of IPv6 ACLs:
• IPv6 router ACLs are supported on outbound or inbound traffic on Layer 3 interfaces, which can be
routed ports, switch virtual interfaces (SVIs), or Layer 3 EtherChannels. IPv6 router ACLs apply only
to IPv6 packets that are routed.
• IPv6 port ACLs are supported on inbound Layer 2 interfaces. IPv6 port ACLs are applied to all IPv6
packets entering the interface.
The switch does not support VLAN ACLs (VLAN maps) for IPv6 traffic.
You can apply both IPv4 and IPv6 ACLs to an interface. As with IPv4 ACLs, IPv6 port ACLs take precedence
over router ACLs.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
1219
Information About Configuring IPv6 ACLs