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S600-E V200R013C00 Configuration Guide - IP Unicast Routing

This document describes the configurations of IP Unicast Routing, including IP Routing, Static Route, RIP, RIPng, OSPF, OSPFv3, Routing Policy, IP Routing Table Management, and PBR.
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Routing Policy Fundamentals

Routing Policy Fundamentals


A filter is the core of a routing policy and is used to define a set of matching rules. The switch provides the filters listed in Table 7-2.

Table 7-2  Comparisons between filters


Applicable Scope

Matching Rules

Access control list (ACL)

Dynamic routing protocols

Inbound interface, source or destination IP address, protocol type, and source or destination port number

IP prefix list

Dynamic routing protocols

Source and destination IP addresses and next hop address


Dynamic routing protocols

Destination IP address, next-hop address, cost, interface information, route type, ACL, IP prefix list, AS_Path filter, community filter, extcommunity filter, and RD filter

The ACL, IP prefix list, AS_Path filter, community filter, extcommunity filter, and RD filter can be used only to filter routes but not modify attributes of filtered routes. A route-policy is a comprehensive filter, and it can use the matching rules of the ACL, IP prefix list, AS_Path filter, community filter, extcommunity filter, and RD filter to filter routes. In addition, attributes of filtered routes can be modified using the route-policy. The following describes these filters.


An ACL is a set of sequential filtering rules. Users can define rules based on packet information, such as inbound interfaces, source or destination IP addresses, protocol types, and source or destination port numbers, and specify an action to deny or permit packets. After an ACL is configured, the system classifies received packets based on the rules defined in the ACL and denies or permits the packets accordingly.

An ACL only classifies packets based on defined rules and can be used to filter packets only when it is applied to a routing policy.

ACLs can be configured for both IPv4 packets and IPv6 packets. Users can specify the IP address and subnet address range in an ACL to match the source IP address, destination network segment address, or next-hop address of a route.

IP Prefix List

An IP prefix list contains a group of route filtering rules. Users can specify the prefix and mask length range to match the destination network segment address or next-hop address of a route. An IP prefix list is used to filter routes that are advertised and received by dynamic routing protocols.

An IP prefix list is easier to configure and more flexible than an ACL. However, if a large number of routes with different prefixes need to be filtered, it is complex to configure an IP prefix list to filter these routes.

IP prefix lists can be configured for both IPv4 routes and IPv6 routes, and these IP prefix lists share the same implementation process. An IP prefix list filters routes based on the mask length or mask length range.
  • Mask length: An IP prefix list filters routes based on IP address prefixes. An IP address prefix is defined by an IP address and a mask length. For example, for the route to, the mask length is 16 bits, and the valid prefix is 16 bits (
  • Mask length range: If routes have the same IP address prefix but different masks, the prefix mask length range can be specified for exact match or for matching routes within the specified mask length range.
NOTE: is a wildcard address. If the IP prefix is, either a mask or a mask length range can be specified following the prefix:
  • If a mask is specified, all routes with this mask are permitted or denied.
  • If a mask length range is specified, all routes with the mask length in this range are permitted or denied.


A route-policy is a complex filter. It is used to match attributes of specified routes and change route attributes when specific conditions are met. A route-policy can use the preceding six filters to define its matching rules.

Invoking Between Tools in Routing Policy

In applications, to control routes, tools used in routing policy must be used together. Figure 7-3 shows invoking between these tools.

Figure 7-3  Invoking between tools in routing policy

InFigure 7-3, all the tools used in routing policy are classified into the following types:

  • Conditional tool: captures required routes.
  • Policy tool: performs an action on the captured routes, for example, permit, deny, and modify attributes.
  • Invoking tool: applies a routing policy to a specific routing protocol to make the routing policy to take effect.

Among the invoking tools, filter-policy and peer have the policy tool function, so they can directly invoke conditional tools. Other invoking tools must invoke conditional tools through route-policy.

The invoking tool, peer, can invoke all conditional tools except ACL.

Updated: 2019-04-08

Document ID: EDOC1100066165

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