This article explains how to configure filter setup for OSPF and RIP. A filter is required for example when redistributing routes from one protocol to another. Route maps can be used to modify routing information. In route maps, the filter is applied to match the routes. Some set actions can be applied to the matching routes.
Example: The RIP learned route 10.0.0.0 /24 with metric 4 hops should have metric 6 instead. The match condition in the route map must be a filter matching 10.0.0.0/24 and the set condition must be metric 6.
When applying route filters in the RIP or OSPF section, only ACLs or Prefix-lists but no route maps are needed.
- Go to CONFIGURATION > Configuration Tree > Box > Virtual Servers > your virtual server > Assigned Services > OSPF-RIP-BGP-Service > OSPF/RIP/BGP Settings.
- Click Lock.
In the left menu, click Filter Setup IPv4 (when using IPv6 addresses, select Filter Setup IPv6 and configure the settings for IPv6).
Access List IPv4 Filters
This section allows the definition of filters which can be referenced within the OSPF Area Setup (see: How to Configure OSPF Routers and Areas) and within the RIP Route Update Filtering section (see: How to Configure RIP Router Setup).Setting Description Name This is the ACL name / ID. Description A short description of the ACL. Network Prefix Enter the network prefix. Type Specifies if the traffic is allowed or blocked: permit (default) / deny Route Map IPv4 Filters
Route maps are used to control and modify routing information that is exchanged between routing domains.
Setting Description Name This is the Route Map Name. Route Map IPv4 Configuration A short description of the route map. OSPF Specific Conditions Sequence Number Unique identifier for a route map entry. Type Action for route map: permit (default) / deny Match Condition
The route map entry matches when the route matches the configured criteria or filter:- ACL (default)
- PREFIXLIST
- Gateway-IP
- Interface-Name
- ACL Name – Name of ACL defined in the Access-Lists section above.
- IP Prefix List – Name of IP prefix list defined in OSPF/RIP Settings - Filter Setup - IPv4 Prefix List Filters.
- Gateway IP – IP address of the next hop in the route.
- Out Interface Name – See interfaces to gain available interface names.
- Set Action – Defines action to set: Metric / Metric-Type
- Set OSPF Metric – Set metric for route map.
- Set OSPF External Metric – Set external metric-type for route map.
RIP Specific Conditions Sequence Number Unique identifier for a route map entry. Type Action for route map: permit (default) / deny Match Condition
The route map entry matches when the route matches the configured criteria or filter:
- ACL (default)
- PREFIXLIST
- Gateway-IP
- Interface-Name
- Metric
- ACL Name – Name of ACL defined in the Access-Lists section above.
- IP Prefix List – Name of IP prefix list defined in OSPF/RIP Settings - Filter Setup - IP Prefix List Filters.
- Gateway IP – IP of the Next Hop in the route.
- Out Interface Name – See interfaces to gain available interface names.
- Match Metric – Defines when a route map is used.
- Set Action – Defines action to set: Next Hop / Metric
- Set RIP Metric – Set metric for route map.
- Set RIP Next-Hop IP – Set next-hop IP address.
IPv4 Prefix List Filters
Prefix lists are easier to understand for route-filters than ACLs. Example for IP prefix list filter usage:
Network Prefix
Type
Extent Type
Deny default route 0.0.0.0/32
0.0.0.0/32
deny none permit prefix 10.0.0.0/24
10.0.0.0/24
permit none Setting Description Name This is the name of the IP prefix list. IPv4 Prefix List Configuration Description A short description of the IP prefix list. Sequence Number Unique identifier for a prefixlist item. Network Prefix Network/Netmask Type Action for prefixterm: permit / deny Extent Type
Matching condition:- none (default)
- greater-than
- less-than
Prefix Length Minimum or maximum prefix length to be matched. - Click OK to confirm your settings.
- Click Send Changes and Activate.