Global RIP Settings Overview
A global RIP setting affects operations on all RIP-enabled interfaces. You configure global settings in the virtual router.
For instructions for configuring RIP settings on the virtual router and on the interface, see the Network and Security Manager Online Help.
Configuring RIP Parameters
You can configure the RIP instance parameters displayed in Table 1.
Table 1: RIP Instance Parameters
RIP Version (ScreenOS 5.1 and later only)
Select the version of RIP you want to use for this virtual router. When you configure RIP on the individual interfaces, you can override this setting.
Reject Default Route
Select this option to prevent route detour attacks in which a router injects a default route (0.0.0.0/0) into the routing domain to detour packets to itself. During a route detour attack, a compromised router can drop the packets, causing service disruption, or can obtain sensitive information in the packets before forwarding them. By default, this option is disabled, meaning RIP accepts any default routes that are learned in RIP and adds the default route to the routing table.
Ignore Same Subnet Checking
Select this option to allow RIP neighbors on different subnets.
Advertising Default Route
Select this option to direct the VR to advertise an active default route (0.0.0.0/0) in the VR route table to all RIP areas.
Configure the default metric for routes that RIP imports from other protocols, such as OSPF and BGP. By default, RIP assigns a metric of 10 to all imported routes.
Number of Alternate Routes for Prefix Allowed (ScreenOS 5.1 and later only)
Configure the maximum number of RIP routes for the same prefix that RIP can add to the RIP route database. By default, RIP does not allow alternate routes.
Hold Down Time for Routes (ScreenOS 5.1 and later only)
Configure the number of seconds that RIP waits before updating the routing table. Use this option to prevent route flapping when handling high metric routes. By default, RIP waits 120 seconds between routing table updates. When configuring this option:
Retransmit Interval for Demand Circuits (ScreenOS 5.1 and later only)
Configure the number of seconds that elapse before RIP resends the RIP routing table to a demand circuit neighbor that did not respond. You can also configure the number of times RIP attempts to retransmit the routing table. By default, RIP resends every 5 seconds.
Poll Interval for Demand Circuits (ScreenOS 5.1 and later only)
Configure the number of seconds between demand circuit checks. By default, RIP sends a request through the demand circuit every three minutes to verify that the tunnel interface is up. You can also configure the number of times a demand circuit must fail to respond before RIP considers the circuit down. By default, RIP never considers an unresponsive circuit down (Number of Retries is 0).
Configure the following timers:
Maximum Route Update Packets
Configure the maximum number of packets that the VR can receive per RIP update.
Maximum Neighbors Allowed on One Interface
Configure the maximum number of RIP neighbors allowed on a single interface. By default, RIP allows up to 16 neighbors for the same interface.
Access List for Filtering Trusted Neighbors
Configure the access list that defines trusted RIP neighbors. If you do not select an access list, RIP uses multicasting or broadcasting to detect neighbors on a RIP-enabled interface.
To control which routes RIP learns and advertises, configure the following:
Configuring RIP Redistribution Rules
Use route redistribution to exchange route information between routing protocols. You can redistribute the following types of routes into the RIP routing instance in the same VR:
Routes learned from BGP
Routes learned from OSPF
Directly connected routes
Statically configured routes
When you configure route redistribution, you must first specify a route map to filter the routes that are redistributed.
Configuring RIP Summary Import (ScreenOS 5.1 and later only)
In large internetworks where hundreds or even thousands of network addresses can exist, routers can become overly congested with route information. After you have redistributed a series of routes from an external protocol to the current RIP routing instance, you can bundle the routes into one generalized or summarized network route. By summarizing multiple addresses, you enable a series of routes to be recognized as one route, simplifying the process.
Using route summarization in a large, complex network can isolate topology changes from other routers. An intermittently failing link in a domain does not affect the summary route, so no router external to the domain needs to modify its routing table due to the link failure.
You can summarize inter area routes or external routes.