Alcatel-Lucent 7750 SR-OS, Configuration Manual

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ACL Filter Policy Overview
Page 408 7750 SR OS Router Configuration Guide
ACL Filter Policy Overview
ACL Filter policies, also referred to as Access Control Lists (ACLs) or filter for short, are sets of
ordered rules specifying packet match criteria and actions to be performed upon a match. Filters
are applied to services or network ports to control network traffic into (ingress) or out of (egress) a
service access port (SAP) or network. There are three main types of filter policies: IPv4, IPv6, and
MAC filter policies. The same filter can be applied to ingress traffic, egress traffic, or both. Ingress
filters affect only inbound traffic destined for the routing complex, and egress filters affect only
outbound traffic sent from the routing complex.
Configuring an entity with a filter policy is optional. By default, there are no filters associated with
services or interfaces, and therefore, all traffic is allowed on the ingress and egress interfaces. The
filter must be explicitly created and associated. There are different types of filter policies as
defined by the scope argument of the filter policy. An exclusive filter is intended to be used by a
single SAP/interface, a template filter is intended to be shared by multiple SAP/interfaces in the
system, and an embedded filter is intended to define common filter rules that can then be used
(embedded) by other filters in the system. Filter policies are created with a unique filter ID, but
each filter has also a unique filter name argument that can be defined once the filter policy has been
created. Either filter ID or filter name can then be used throughout the system to manage filter
policies and their associations.
On a Layer 2 SAP, either a single IP (v4 or v6) or a single MAC filter policy can be applied in a
given direction. On a Layer 3 SAP and network interfaces, a single IP (v4 or v6) can be applied in
a given direction. The ingress and egress direction policies can be same or different. For dual stack
IPv4/IPv6 SAPs/interfaces, if both IPv4 and IPv6 filter policies are defined, the policy applied will
be based on the outer IP header of the packet. Note that non-IP packets are not hitting an IP filter
policy, so the default action in the IP filter policy will not apply to these packets.