Huawei Quidway NetEngine80E Configuration Manual page 913

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
Figure 8-11 BGP route selection process
Multiple routes to the same
BGP selects routes by comparing route attributes in a fixed order. When a route attribute is a
sufficient condition for determining the optimal route, BGP does not compare the other
attributes; If BGP fails to select the optimal route after comparing all route attributes, the route
that was first received is selected as the optimal
route selection rules, and remarks of each matching item.
is directly proportional to the PreVal or Local_Pref value and inversely proportional to the rest
of the attribute values or lengths. In addition, the first column can be summarized as a character
string (PPAAA OMTCC RA), which helps memorize the matching sequence.
Issue 02 (2014-09-30)
destination are available.
Are PrefVal values
the same?
Yes
Are Local_Pref values
the same?
Yes
Are they generated
the same way?
Yes
Are AIGP values
the same?
Yes
Are AS_Path lengths
the same?
Yes
Are Origin types
the same?
Are MEDs
the same?
Yes
Are peer types
the same?
Yes
Are IGP costs
the same?
Yes
Are Cluster_List lengths
the same?
Yes
Are router IDs
the same?
Yes
Are peer addresses
the same?
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Is the next hop address reachable?
Yes
The route with the largest PrefVal
value is preferred.
No
The route with the largest
Local_Pref value is preferred.
No
Aggregate>Summary>Network
>Import>Learned from peers
No
The route with the smallest AIGP is
preferred, and the route with AIGP is
No
preferred to the route without AIGP.
The route with the shortest AS_Path
length is preferred.
No
IGP > EGP > Incomplete
No
The one with the smallest MED
value is preferred.
No
EBGP > IBGP
No
The one with the smallest IGP cost
value is preferred.
No
The route with the shortest
Cluster_List length is preferred.
No
The route with the smallest router ID
is preferred.
No
The route with the smallest peer
address is preferred.
No
route.Table 8-10
Table 8-10
8 BGP Configuration
No
The route is
ignored.
The optimal
route is selected.
lists the abbreviated alias,
shows that the route priority
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