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Use these commands to create route map instances. There is no limit to the number of set and match
commands per route map, but the convention is to keep the number of match and set filters in a route map
low.
Set commands do not require a corresponding match command.
Configure a Route Map for Route Redistribution
Route maps on their own cannot affect traffic and must be included in different commands to affect routing
traffic. To apply a route map to traffic, you must call or include that route map in a command such as the
redistribute or default-information originate commands in OSPF and BGP.
Route redistribution occurs when FTOS learns the advertising routes from static or directly connected
routes or another routing protocol. Different protocols assign different values to redistributed routes to
identify either the routes and their origins. The metric value is the most common attribute that is changed
to properly redistribute other routes into a routing protocol. Other attributes that can be changed include
the metric type (for example, external and internal route types in OSPF) and the route tag. Use the
redistribute command in OSPF, RIP, and BGP to set some of these attributes for routes that are redistributed
into those protocols.
Route maps add to that redistribution capability by allowing you to match specific routes and set or change
more attributes when redistributing those routes.
In Figure 5-27, the
redistribute command calls the route map static ospf to redistribute only certain
static routes into OSPF. According to the route map static ospf, only routes that have a next hop of
TenGigabitethernet interface 0/0 and that have a metric of 255 are redistributed into the OSPF backbone
area.
Figure 5-27. Route Redistribution into OSPF
Configure a Route Map for Route Tagging
One method for identifying routes from different routing protocols is to assign a tag to routes from that
protocol. As the route enters a different routing domain, it is tagged and that tag is passed along with the
route as it passes through different routing protocols. Use this tag when the route leaves a routing domain
to redistribute those routes again.
Note: When re-distributing routes using route-maps, you must take care to create the route-map defined
in the redistribute command under the routing protocol. If no route-map is created, then NO routes are
redistributed.
router ospf 34
default-information originate metric-type 1
redistribute static metric 20 metric-type 2 tag 0 route-map staticospf
!
route-map staticospf permit 10
match interface TenGigabitEthernet 0/0
match metric 255
set level backbone
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