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Policy Framework Terms

Before configuring routing policies or firewall filters on a Services Router, you must become familiar with the terms defined in Table 58.

Table 58: Policy Framework Terms

Term

Definition

action

Operation performed if a route or packet matches all criteria defined in a match condition. Actions are configured in terms. You can specify one or more actions in a term. See also match condition; term.

firewall filter

See stateful firewall filter; stateless firewall filter.

match condition

Criteria that an incoming or an outgoing route or packet on a Services Router must match for an action to occur. Match conditions are specified in terms. If you specify more than one match condition, all the conditions must match in a route or packet for an action to occur. See also action; term.

multifield (MF) classifier

Firewall filter that scans through a variety of packet fields to determine the forwarding class and loss priority for a packet and polices traffic to a specific bandwidth and burst size. Typically, a classifier performs matching operations on the selected fields against a configured value.

Network Address Port Translation (NAPT)

Method of concealing a set of host ports on a private network behind a pool of public addresses. NAPT can be used as a security measure to protect the host ports from direct targeting in network attacks.

Network Address Translation (NAT)

Method of concealing a set of host addresses on a private network behind a pool of public addresses. NAT can be used as a security measure to protect the host addresses from direct targeting in network attacks.

policer

Component of firewall filters that limits the amount of traffic passing into or out of an interface to thwart denial-of-service (DoS) attacks. A policer applies rate limits on bandwidth and burst size for traffic on a particular Services Router interface.

service set

Collection of services. Examples of services include stateful firewall filters and Network Address Translation (NAT).

stateful firewall filter

Type of firewall filter that evaluates the context of connections, permits or denies traffic based on the context, and updates this information dynamically. The context includes IP source and destination addresses, TCP port numbers, TCP sequencing information, and TCP connection flags.

stateless firewall filter

Type of firewall filter that statically evaluates the contents of packets transiting the router and packets originating from, or destined for, the router. Information about connection states is not maintained.

term

Component of a routing policy or firewall filter that defines its criteria (match conditions) and results (actions). A routing policy or firewall filter can have one or multiple terms. See also match condition; action.

trusted network

Network from which all originating traffic can be trusted—for example, an internal enterprise LAN. Stateful firewall filters allow traffic to flow from trusted to untrusted networks.

untrusted network

Network from which all originating traffic cannot be trusted—for example, a WAN. Unless configured otherwise, stateful firewall filters do not allow traffic to flow from untrusted to trusted networks.


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