Cisco 10000-2P2-2DC Software Guide - Page 548

IPv6 Extended ACLs, Prerequisites, Restrictions

Page 548 highlights

IPv6 Extended ACLs Chapter 24 Configuring IP Version 6 • ACL logging • Time-based ACLs • Reflexive ACLs • Receive Path ACLs • MiniACLs QoS matching is not provided on the following two fields, which are IPv6-specific: • IPv6 src/dst address • IPv6 ACL IPv6 Extended ACLs Access lists determine what traffic is blocked and what traffic is forwarded at router interfaces and allow filtering based on source and destination addresses, inbound and outbound to a specific interface. Each access list has an implicit deny statement at the end. IPv6 ACLs are defined and their deny and permit conditions are set using the ipv6 access-list command with the deny and permit keywords in global configuration mode. In Cisco IOS Release 12.2(31)SB2 and later releases, the standard IPv6 ACL functionality is extended to support traffic filtering based on IPv6 option headers and optional, upper-layer protocol type information for finer granularity of control (functionality similar to extended ACLs in IPv4). Prerequisites In Cisco IOS Release 12.2(13)T and 12.0(23)S or later releases, for backward compatibility, the ipv6 access-list command with the deny and permit keywords in global configuration mode is still supported; however, an IPv6 ACL defined with deny and permit conditions in global configuration mode is translated to IPv6 access list configuration mode. See the "Create and Apply IPv6 ACL: Examples" section for an example of a translated IPv6 ACL configuration. Restrictions IPv6 ACLs are defined by a unique name (IPv6 does not support numbered ACLs). An IPv4 ACL and an IPv6 ACL cannot share the same name. • Each IPv6 ACL contains implicit permit rules to enable IPv6 neighbor discovery. These rules can be overridden by the user by placing a deny ipv6 any any statement within an ACL. The IPv6 neighbor discovery process makes use of the IPv6 network layer service; therefore, by default, IPv6 ACLs implicitly allow IPv6 neighbor discovery packets to be sent and received on an interface. In IPv4, the Address Resolution Protocol (ARP), which is equivalent to the IPv6 neighbor discovery process, makes use of a separate data link layer protocol; therefore, by default, IPv4 ACLs implicitly allow ARP packets to be sent and received on an interface. 24-4 Cisco 10000 Series Router Software Configuration Guide OL-2226-23

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24-4
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
Chapter 24
Configuring IP Version 6
IPv6 Extended ACLs
ACL logging
Time-based ACLs
Reflexive ACLs
Receive Path ACLs
MiniACLs
QoS matching is not provided on the following two fields, which are IPv6-specific:
IPv6 src/dst address
IPv6 ACL
IPv6 Extended ACLs
Access lists determine what traffic is blocked and what traffic is forwarded at router interfaces and allow
filtering based on source and destination addresses, inbound and outbound to a specific interface. Each
access list has an implicit deny statement at the end. IPv6 ACLs are defined and their deny and permit
conditions are set using the
ipv6 access-list
command with the
deny
and
permit
keywords in global
configuration mode.
In Cisco IOS Release 12.2(31)SB2 and later releases, the standard IPv6 ACL functionality is extended
to support traffic filtering based on IPv6 option headers and optional, upper-layer protocol type
information for finer granularity of control (functionality similar to extended ACLs in IPv4).
Prerequisites
In Cisco IOS Release 12.2(13)T and 12.0(23)S or later releases, for backward compatibility, the
ipv6
access-list
command with the
deny
and
permit
keywords in global configuration mode is still
supported; however, an IPv6 ACL defined with deny and permit conditions in global configuration mode
is translated to IPv6 access list configuration mode. See the
“Create and Apply IPv6 ACL: Examples”
section for an example of a translated IPv6 ACL configuration.
Restrictions
IPv6 ACLs are defined by a unique name (IPv6 does not support numbered ACLs). An IPv4 ACL and
an IPv6 ACL cannot share the same name.
Each IPv6 ACL contains implicit permit rules to enable IPv6 neighbor discovery. These rules can
be overridden by the user by placing a
deny ipv6 any any
statement within an ACL. The IPv6
neighbor discovery process makes use of the IPv6 network layer service; therefore, by default, IPv6
ACLs implicitly allow IPv6 neighbor discovery packets to be sent and received on an interface. In
IPv4, the Address Resolution Protocol (ARP), which is equivalent to the IPv6 neighbor discovery
process, makes use of a separate data link layer protocol; therefore, by default, IPv4 ACLs implicitly
allow ARP packets to be sent and received on an interface.