Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

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If you specify a BGP peer group by using the peerGroupName argument, all the members
of the peer group inherit the characteristic configured with this command unless it is
overridden for a specific peer.
•
You can set a weight value for inbound routes filtered with a filter list.
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Example
host1# test ip bgp neighbor 10.12.54.21 advertised-routes distribute-list boston5 fields
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There is no no version.
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See test bgp ipv6 neighbor.
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See test ip bgp neighbor.
Selecting the Best Path
BGP selects only one route to a destination as the best path . When multiple routes to a
given destination exist, BGP must determine which of these routes is the best. BGP puts
the best path in its routing table and advertises that path to its BGP neighbors.
If only one route exists to a particular destination, BGP installs that route. If multiple
routes exist for a destination, BGP uses tie-breaking rules to decide which one of the
routes to install in the BGP routing table.
BGP Path Decision Algorithm
BGP determines the best path to each destination for a BGP speaker by comparing path
attributes according to the following selection sequence:
1.
Select a path with a reachable next hop .
2.
Select the path with the highest weight .
3.
If path weights are the same, select the path with the highest local preference value.
4.
Prefer locally originated routes (network routes, redistributed routes, or aggregated
routes) over received routes.
5.
Select the route with the shortest AS-path length.
6.
If all paths have the same AS-path length, select the path based on origin : IGP is
preferred over EGP; EGP is preferred over Incomplete.
7.
If the origins are the same, select the path with lowest MED value.
8.
If the paths have the same MED values, select the path learned by means of EBGP
over one learned by means of IBGP.
9.
Select the path with the lowest IGP cost to the next hop.
10.
Select the path with the shortest route reflection cluster list. Routes without a cluster
list are treated as having a cluster list of length 0.
Copyright © 2010, Juniper Networks, Inc. 104
JunosE 11.2.x BGP and MPLS Configuration Guide