Juniper JUNOSE, Configuration Manual

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test ip bgp neighbor
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Use to test the effect of BGP policies on a router without implementing the policy.
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You can apply the test to routes advertised to peers or received from peers.
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You can test the following kinds of policies: distribute lists, filter lists, prefix lists,
prefix trees, or route maps. If you do not specify a policy, then the test uses
whatever policies are currently in effect on the router.
NOTE: If you test the current policies, the results might vary for routes learned before
the current policies were activated if you did not clear the forwarding table when
the policies changed.
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The following three items apply to the test ip bgp neighbor command only:
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The address-family identifier for the route is the same as is used for identifying
the neighbor.
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If you do not specify a route, the test is performed for all routes associated
with the
address-family identifier .
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Specifying only an address and mask without a route distinguisher causes
all routes sharing the address and mask to be considered. Specifying only
an address causes a best match to be performed for the route.
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If you completely specify a route with IP address, mask, and route distinguisher,
the command displays detailed route information. Otherwise only summary
information is shown. Use the
fields option to select particular fields of interest.
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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.
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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.
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Selecting the Best Path
JUNOSe 11.0.x BGP and MPLS Configuration Guide