Juniper JUNOSE 11.2.X BGP AND MPLS, Руководство по настройке

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Behavior is different for outbound policies configured for peer groups for which you
have enabled Adj-RIBs-Out. If you change the outbound policy for such a peer group
and want to fill the Adj-RIBs-Out table for that peer group with the results of the new
policy, you must use the
clear ip bgp peer-group command to perform a hard clear or
outbound soft clear of the peer group. You cannot merely perform a hard clear or
outbound soft clear for individual peer group members because that causes BGP to
resend only the contents of the Adj-RIBs-Out table.
•
Issuing this command automatically removes the neighbor next-hop-unchanged
configuration (enabled or disabled) on the peer or peer group. Issuing the no or default
version of this command has no effect on the neighbor next-hop-unchanged
configuration.
•
Use the no version to disable this feature (and therefore enable next-hop processing
of BGP updates). Use the default version to remove the explicit configuration from
the peer or peer group and reestablish inheritance of the feature configuration.
•
See neighbor next-hop-self.
Assigning a Weight to a Route
You can assign a weight to a route when more than one route exists to the same
destination. A weight indicates a preference for that particular route over the other routes
to that destination. The higher the assigned weight, the more preferred the route. By
default, the route weight is 32768 for paths originated by the router, and 0 for other paths.
In the configuration shown in Figure 31 on page 109, routers Boston and NY both learn
about network 192.68.5.0/24 from AS 200. Routers Boston and NY both propagate the
route to router LA. Router LA now has two routes for reaching 192.68.5.0/24 and must
decide the appropriate route. If you prefer that router LA direct traffic through router
Boston, you can configure router LA so that the weight of routes coming from router
Boston are higher—more preferred—than the routes coming from router NY. Router LA
subsequently prefers routes received from router Boston and therefore uses router Boston
as the next hop to reach network 192.68.5.0/24.
Figure 31: Assigning a Weight to a Neighbor Connection
109 Copyright © 2010, Juniper Networks, Inc.
Chapter 1: Configuring BGP Routing