Technical information

ADC Telecommunications, Inc.
360 C
HAPTER 13: CREATING ROUTE FILTERS
Import and Export Route Filtering for RIP and OSPF
The Cuda 12000 uses route filtering functions to control the flow of routes
to and from other RIP and OSPF routers. Two filtering functions are
supported for control of RIP and OSPF routes; they are: import and export.
■ Import — Controls how routes are added to the Cuda 12000 routing
table.
■ Export — Controls which routes are advertised to other routers.
In addition, route filtering customizes connectivity, increase security, conserve
routing table space, or adjust route cost.
To understand route filtering, you must be familiar with these functions:
■ Access Control Element (ACE) — A structure that defines the match
criteria and the action that you want the Cuda 12000 to take for all
routes that match the specified criteria.
■ Access Control List (ACL) — A sequential grouping of ACEs. An incoming
or outgoing route is compared against all ACEs that comprise the ACL.
Whenever a route match is found, the system takes the action that is
defined in the ACE.
Defining RIP and OSPF route filtering is a two-step process:
■ First, you create the ACEs to define both the match criteria and the action
to take when a route match is found.
■ Second, you create the ACL by selecting ACEs from a pool, and making
them part of an ACL.
Following is an example that includes ACE templates 1, 2, and 3, and the
ACLs created with these ACEs. Note the following from the example:
■ ACLs are made up of one or more ACEs.
■ The same ACE may be shared in multiple ACLs.
■ ACEs within each ACL must be sorted in order of the specific-to-
general match criteria and action needs of the ACL.