Bgp route selection, Configuring bgp, Configuration prerequisites – H3C Technologies H3C SecPath F1000-E User Manual
Page 334: Configuration overview
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No_Export: After received, routes with this attribute cannot be advertised out the local AS or out the
local confederation but can be advertised to other sub-ASs in the confederation.
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No_Advertise: After received, routes with this attribute cannot be advertised to other BGP peers.
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No_Export_Subconfed: After received, routes with this attribute cannot be advertised out the local
AS or other ASs in the local confederation.
BGP Route Selection
The current BGP implementation supports the following route selection sequence:
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Discard routes with unreachable NEXT_HOPs first
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Select the route with the highest Preferred_value
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Select the route with the highest LOCAL_PREF
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Select the route originated by the local router
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Select the route with the shortest AS-PATH
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Select IGP, EGP, Incomplete routes in turn
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Select the route with the lowest MED value
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Select routes learned from eBGP, confederation, iBGP in turn
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Select the route with the smallest next hop cost
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Select the route with the shortest CLUSTER_LIST
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Select the route with the smallest ORIGINATOR_ID
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Select the route advertised by the router with the smallest Router ID
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Select the route with the lowest IP address
NOTE:
CLUSTER_IDs of route reflectors form a CLUSTER_LIST. If a route reflector receives a route that contains its
own CLUSTER ID in the CLUSTER_LIST, the router discards the route to avoid routing loops.
Configuring BGP
Configuration Prerequisites
Before configuring BGP, you need to configure the link layer protocol, and IP addresses for interfaces,
making neighboring nodes accessible with each other at the network layer.
Configuration Overview
Perform the tasks in
to configure BGP.
Table 2 BGP configuration task list
Task Remarks
Enable BGP
Required
Enable BGP and specify an AS number.