Policy Management Overview

This chapter introduces policy-based routing management on E Series routers. Policy management enables you to configure, manage, and monitor policies that selectively cause packets to take different paths without requiring a routing table lookup. The JunosE Software’s packet-mirroring feature uses secure policies.

Policy management enables network service providers to configure services that customize the treatment of individual packet flows received on a subscriber’s interface. The main tool for implementing policy management is a policy list. A policy list is a set of rules, each of which specifies a policy action. A rule is a policy action optionally combined with a classification.

Packets are sorted at ingress or egress into packet flows based on attributes defined in classifier control lists (CLACLs). You can apply policy lists to packets arriving and leaving an interface. You can use policy management on ATM, Frame Relay, generic routing encapsulation (GRE), IP, IPv6, Layer 2 Tunneling Protocol (L2TP), Multiprotocol Label Switching (MPLS), and virtual local area network (VLAN) traffic.

Policy management provides:

Policy management gives you the CLI tools to build databases, which can then be drawn from to implement a policy. Each database contains global traffic specifications. When building a policy, you specify input from one or more of these databases and then attach the policy to an interface. By combining the information from the various databases into policies, you can deploy a wide variety of services.

Note: When applying policies to interfaces that are managed by the SRC, avoid using any other policy management tools, such as CLI, RADIUS, COA, or Service Manager. SRC is not compatible with other types of policy management tools. When policies are applied to the interface before SRC management begins, such as at access-accept time, these policies are properly replaced. However, if other policy managers change existing policies while SRC management is active, problems can occur. The precedence of each source when modifying configurations is:

  • If you have a pre-configured policy through CLI as part of subscriber PVC/VLAN provisioning, SRC overwrites the policy when the SRC manages the interface
  • If you have a policy in the Access-Accept, SRC overwrites the policy when the SRC manages the interface

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