HPE FlexNetwork HSR6800 Configuration Manual page 200

Figure 62 LOCAL_PREF attribute
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COMMUNITY
The COMMUNITY attribute identifies the community of BGP routes. A BGP community is a
group of routes with the same characteristics. It has no geographical boundaries. Routes of
different ASs can belong to the same community.
A route can carry one or more COMMUNITY attribute values (each of which is represented by a
four-byte integer). A router uses the COMMUNITY attribute to determine whether to advertise
the route and the advertising scope without using complex filters, such as ACLs. This
mechanism simplifies routing policy configuration, management, and maintenance.
Well-known community attributes involve the following:
Internet—By default, all routes belong to the Internet community. Routes with this attribute can be
advertised to all BGP peers.
No_Export—Routes with this attribute cannot be advertised out of the local AS or out of the local
confederation, but can be advertised to other sub ASs in the confederation. For confederation information, see
"Settlements for problems in large-scale BGP
No_Advertise—Routes with this attribute cannot be advertised to other BGP peers.
No_Export_Subconfed—Routes with this attribute cannot be advertised out of the local AS or other sub
ASs in the local confederation.
You can configure BGP community lists to filter BGP routes based on the BGP community
attribute.
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Extended community attribute
To meet new demands, BGP defines the extended community attribute. The extended
community attribute has the following advantages over the community attribute:
Provides more attribute values by extending the attribute length to eight bytes.
Allows for using different types of extended community attributes in different scenarios to enhance route
filtering and control and simplify configuration and management.
The device supports the Route-Target attribute for VPN and Source of Origin (SoO) attribute.
For more information, see MPLS Configuration Guide.
networks."
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