- play_arrow Understanding and Configuring Junos Routing Policies
- play_arrow Overview
- Policy Framework Overview
- Comparison of Routing Policies and Firewall Filters
- Prefix Prioritization Overview
- FIB Prefix Prioritization
- Accounting of the Policer Overhead Attribute at the Interface Level
- Configuring the Accounting of Policer Overhead in Interface Statistics
- Understanding Routing Policies
- Protocol Support for Import and Export Policies
- Example: Applying Routing Policies at Different Levels of the BGP Hierarchy
- Default Routing Policies
- Example: Configuring a Conditional Default Route Policy
- play_arrow Evaluating Routing Policies Using Match Conditions, Actions, Terms, and Expressions
- How a Routing Policy Is Evaluated
- Categories of Routing Policy Match Conditions
- Routing Policy Match Conditions
- Route Filter Match Conditions
- Actions in Routing Policy Terms
- Summary of Routing Policy Actions
- Example: Configuring a Routing Policy to Advertise the Best External Route to Internal Peers
- Example: Configuring BGP to Advertise Inactive Routes
- Example: Using Routing Policy to Set a Preference Value for BGP Routes
- Example: Enabling BGP Route Advertisements
- Example: Rejecting Known Invalid Routes
- Example: Using Routing Policy in an ISP Network
- Understanding Policy Expressions
- Understanding Backup Selection Policy for OSPF Protocol
- Configuring Backup Selection Policy for the OSPF Protocol
- Configuring Backup Selection Policy for IS-IS Protocol
- Example: Configuring Backup Selection Policy for the OSPF or OSPF3 Protocol
- play_arrow Evaluating Complex Cases Using Policy Chains and Subroutines
- play_arrow Configuring Route Filters and Prefix Lists as Match Conditions
- Understanding Route Filters for Use in Routing Policy Match Conditions
- Understanding Route Filter and Source Address Filter Lists for Use in Routing Policy Match Conditions
- Understanding Load Balancing Using Source or Destination IP Only
- Configuring Load Balancing Using Source or Destination IP Only
- Walkup for Route Filters Overview
- Configuring Walkup for Route Filters to Improve Operational Efficiency
- Example: Configuring Route Filter Lists
- Example: Configuring Walkup for Route Filters Globally to Improve Operational Efficiency
- Example: Configuring Walkup for Route Filters Locally to Improve Operational Efficiency
- Example: Configuring a Route Filter Policy to Specify Priority for Prefixes Learned Through OSPF
- Example: Configuring the MED Using Route Filters
- Example: Configuring Layer 3 VPN Protocol Family Qualifiers for Route Filters
- Understanding Prefix Lists for Use in Routing Policy Match Conditions
- Example: Configuring Routing Policy Prefix Lists
- Example: Configuring the Priority for Route Prefixes in the RPD Infrastructure
- Configuring Priority for Route Prefixes in RPD Infrastructure
- play_arrow Configuring AS Paths as Match Conditions
- Understanding AS Path Regular Expressions for Use as Routing Policy Match Conditions
- Example: Using AS Path Regular Expressions
- Understanding Prepending AS Numbers to BGP AS Paths
- Example: Configuring a Routing Policy for AS Path Prepending
- Understanding Adding AS Numbers to BGP AS Paths
- Example: Advertising Multiple Paths in BGP
- Improve the Performance of AS Path Lookup in BGP Policy
- play_arrow Configuring Communities as Match Conditions
- Understanding BGP Communities, Extended Communities, and Large Communities as Routing Policy Match Conditions
- Understanding How to Define BGP Communities and Extended Communities
- How BGP Communities and Extended Communities Are Evaluated in Routing Policy Match Conditions
- Example: Configuring Communities in a Routing Policy
- Example: Configuring Extended Communities in a Routing Policy
- Example: Configuring BGP Large Communities
- Example: Configuring a Routing Policy Based on the Number of BGP Communities
- Example: Configuring a Routing Policy That Removes BGP Communities
- play_arrow Increasing Network Stability with BGP Route Flapping Actions
- play_arrow Tracking Traffic Usage with Source Class Usage and Destination Class Usage Actions
- Understanding Source Class Usage and Destination Class Usage Options
- Source Class Usage Overview
- Guidelines for Configuring SCU
- System Requirements for SCU
- Terms and Acronyms for SCU
- Roadmap for Configuring SCU
- Roadmap for Configuring SCU with Layer 3 VPNs
- Configuring Route Filters and Source Classes in a Routing Policy
- Applying the Policy to the Forwarding Table
- Enabling Accounting on Inbound and Outbound Interfaces
- Configuring Input SCU on the vt Interface of the Egress PE Router
- Mapping the SCU-Enabled vt Interface to the VRF Instance
- Configuring SCU on the Output Interface
- Associating an Accounting Profile with SCU Classes
- Verifying Your SCU Accounting Profile
- SCU Configuration
- SCU with Layer 3 VPNs Configuration
- Example: Grouping Source and Destination Prefixes into a Forwarding Class
- play_arrow Avoiding Traffic Routing Threats with Conditional Routing Policies
- Conditional Advertisement and Import Policy (Routing Table) with certain match conditions
- Conditional Advertisement Enabling Conditional Installation of Prefixes Use Cases
- Example: Configuring a Routing Policy for Conditional Advertisement Enabling Conditional Installation of Prefixes in a Routing Table
- play_arrow Protecting Against DoS Attacks by Forwarding Traffic to the Discard Interface
- play_arrow Improving Commit Times with Dynamic Routing Policies
- play_arrow Testing Before Applying Routing Policies
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- play_arrow Configuring Traffic Policers
- play_arrow Understanding Traffic Policers
- Policer Implementation Overview
- ARP Policer Overview
- Example: Configuring ARP Policer
- Understanding the Benefits of Policers and Token Bucket Algorithms
- Determining Proper Burst Size for Traffic Policers
- Controlling Network Access Using Traffic Policing Overview
- Traffic Policer Types
- Order of Policer and Firewall Filter Operations
- Understanding the Frame Length for Policing Packets
- Supported Standards for Policing
- Hierarchical Policer Configuration Overview
- Understanding Enhanced Hierarchical Policers
- Packets-Per-Second (pps)-Based Policer Overview
- Guidelines for Applying Traffic Policers
- Policer Support for Aggregated Ethernet Interfaces Overview
- Example: Configuring a Physical Interface Policer for Aggregate Traffic at a Physical Interface
- Firewall and Policing Differences Between PTX Series Packet Transport Routers and T Series Matrix Routers
- Hierarchical Policers on ACX Series Routers Overview
- Guidelines for Configuring Hierarchical Policers on ACX Series Routers
- Hierarchical Policer Modes on ACX Series Routers
- Processing of Hierarchical Policers on ACX Series Routers
- Actions Performed for Hierarchical Policers on ACX Series Routers
- Configuring Aggregate Parent and Child Policers on ACX Series Routers
- play_arrow Configuring Policer Rate Limits and Actions
- play_arrow Configuring Layer 2 Policers
- Hierarchical Policers
- Configuring a Policer Overhead
- Two-Color and Three-Color Policers at Layer 2
- Layer 2 Traffic Policing at the Pseudowire Overview
- Configuring a Two-Color Layer 2 Policer for the Pseudowire
- Configuring a Three-Color Layer 2 Policer for the Pseudowire
- Applying the Policers to Dynamic Profile Interfaces
- Attaching Dynamic Profiles to Routing Instances
- Using Variables for Layer 2 Traffic Policing at the Pseudowire Overview
- Configuring a Policer for the Complex Configuration
- Creating a Dynamic Profile for the Complex Configuration
- Attaching Dynamic Profiles to Routing Instances for the Complex Configuration
- Verifying Layer 2 Traffic Policers on VPLS Connections
- Understanding Policers on OVSDB-Managed Interfaces
- Example: Applying a Policer to OVSDB-Managed Interfaces
- play_arrow Configuring Two-Color and Three-Color Traffic Policers at Layer 3
- Two-Color Policer Configuration Overview
- Basic Single-Rate Two-Color Policers
- Bandwidth Policers
- Prefix-Specific Counting and Policing Actions
- Policer Overhead to Account for Rate Shaping in the Traffic Manager
- Three-Color Policer Configuration Overview
- Applying Policers
- Three-Color Policer Configuration Guidelines
- Basic Single-Rate Three-Color Policers
- Basic Two-Rate Three-Color Policers
- Example: Configuring a Two-Rate Three-Color Policer
- play_arrow Configuring Logical and Physical Interface Traffic Policers at Layer 3
- play_arrow Configuring Policers on Switches
- Overview of Policers
- Traffic Policer Types
- Understanding the Use of Policers in Firewall Filters
- Understanding Tricolor Marking Architecture
- Configuring Policers to Control Traffic Rates (CLI Procedure)
- Configuring Tricolor Marking Policers
- Understanding Policers with Link Aggregation Groups
- Understanding Color-Blind Mode for Single-Rate Tricolor Marking
- Understanding Color-Aware Mode for Single-Rate Tricolor Marking
- Understanding Color-Blind Mode for Two-Rate Tricolor Marking
- Understanding Color-Aware Mode for Two-Rate Tricolor Marking
- Example: Using Two-Color Policers and Prefix Lists
- Example: Using Policers to Manage Oversubscription
- Assigning Forwarding Classes and Loss Priority
- Configuring Color-Blind Egress Policers for Medium-Low PLP
- Configuring Two-Color and Three-Color Policers to Control Traffic Rates
- Verifying That Two-Color Policers Are Operational
- Verifying That Three-Color Policers Are Operational
- Troubleshooting Policer Configuration
- Troubleshooting Policer Configuration
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- play_arrow Configuration Statements and Operational Commands
- play_arrow Troubleshooting
- play_arrow Knowledge Base
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Understanding How to Use Standard Firewall Filters
Using Standard Firewall Filters to Affect Local Packets
On a router, you can configure one physical loopback interface, lo0, and one or more addresses on the interface. The loopback interface is the interface to the Routing Engine, which runs and monitors all the control protocols. The loopback interface carries local packets only. Standard firewall filters applied to the loopback interface affect the local packets destined for or transmitted from the Routing Engine.
When you create an additional loopback interface, it is important to apply a filter to it so the Routing Engine is protected. We recommend that when you apply a filter to the loopback interface, you include the apply-groups statement. Doing so ensures that the filter is automatically inherited on every loopback interface, including lo0 and other loopback interfaces.
Trusted Sources
The typical use of a standard stateless firewall filter is to protect the Routing Engine processes and resources from malicious or untrusted packets. To protect the processes and resources owned by the Routing Engine, you can use a standard stateless firewall filter that specifies which protocols and services, or applications, are allowed to reach the Routing Engine. Applying this type of filter to the loopback interface ensures that the local packets are from a trusted source and protects the processes running on the Routing Engine from an external attack.
Flood Prevention
You can create standard stateless firewall filters that limit certain TCP and ICMP traffic destined for the Routing Engine. A router without this kind of protection is vulnerable to TCP and ICMP flood attacks, which are also called denial-of-service (DoS) attacks. For example:
A TCP flood attack of SYN packets initiating connection requests can overwhelm the device until it can no longer process legitimate connection requests, resulting in denial of service.
An ICMP flood can overload the device with so many echo requests (ping requests) that it expends all its resources responding and can no longer process valid network traffic, also resulting in denial of service.
Applying the appropriate firewall filters to the Routing Engine protects against these types of attacks.
Using Standard Firewall Filters to Affect Data Packets
Standard firewall filters that you apply to your router’s transit interfaces evaluate only the user data packets that transit the router from one interface directly to another as they are being forwarded from a source to a destination. To protect the network as a whole from unauthorized access and other threats at specific interfaces, you can apply firewall filters router transit interfaces .
