Route Maps - Cisco Catalyst 9500 series Configuration Manual
Cisco ios xe everest 16.6.x
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Configuring IP Unicast Routing
router configuration command. You can disable next-hop processing by using route maps or the neighbor
next-hop-self router configuration command.
2 Prefer the path with the largest weight (a Cisco proprietary parameter). The weight attribute is local to the
router and not propagated in routing updates. By default, the weight attribute is 32768 for paths that the
router originates and zero for other paths. Routes with the largest weight are preferred. You can use access
lists, route maps, or the neighbor weight router configuration command to set weights.
3 Prefer the route with the highest local preference. Local preference is part of the routing update and
exchanged among routers in the same AS. The default value of the local preference attribute is 100. You
can set local preference by using the bgp default local-preference router configuration command or by
using a route map.
4 Prefer the route that was originated by BGP running on the local router.
5 Prefer the route with the shortest AS path.
6 Prefer the route with the lowest origin type. An interior route or IGP is lower than a route learned by EGP,
and an EGP-learned route is lower than one of unknown origin or learned in another way.
7 Prefer the route with the lowest multi -exit discriminator (MED) metric attribute if the neighboring AS is
the same for all routes considered. You can configure the MED by using route maps or by using the
default-metric router configuration command. When an update is sent to an IBGP peer, the MED is
included.
8 Prefer the external (EBGP) path over the internal (IBGP) path.
9 Prefer the route that can be reached through the closest IGP neighbor (the lowest IGP metric). This means
that the router will prefer the shortest internal path within the AS to reach the destination (the shortest path
to the BGP next-hop).
10 If the following conditions are all true, insert the route for this path into the IP routing table:
Both the best route and this route are external.
Both the best route and this route are from the same neighboring autonomous system.
Maximum-paths is enabled.
11 If multipath is not enabled, prefer the route with the lowest IP address value for the BGP router ID. The
router ID is usually the highest IP address on the router or the loopback (virtual) address, but might be
implementation-specific.
Route Maps
Within BGP, route maps can be used to control and to modify routing information and to define the conditions
by which routes are redistributed between routing domains. See the "Using Route Maps to Redistribute Routing
Information" section for more information about route maps. Each route map has a name that identifies the
route map (map tag) and an optional sequence number.
BGP Filtering
You can filter BGP advertisements by using AS-path filters, such as the as-path access-list global configuration
command and the neighbor filter-list router configuration command. You can also use access lists with the
neighbor distribute-list router configuration command. Distribute-list filters are applied to network numbers.
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
Route Maps
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