H3C S3610-28P Operation Manual page 487

Operation Manual – IPv4 Routing
H3C S3610&S5510 Series Ethernet Switches
AGGREGATOR
COMMUNITY
MULTI_EXIT_DISC (MED)
ORIGINATOR_ID
CLUSTER_LIST
II. Usage of BGP path attributes
1) ORIGIN
ORIGIN is a well-known mandatory attribute and defines the origin of routing
information and how a route becomes a BGP route. It involves three types:
IGP: Has the highest priority. Routes added to the BGP routing table using the
network command have the IGP attribute.
EGP: Has the second highest priority. Routes obtained via EGP have the EGP
attribute.
incomplete: Has the lowest priority. The source of routes with this attribute is
unknown, which does not mean such routes are unreachable. The routes
redistributed from other routing protocols have the incomplete attribute.
2) AS_PATH
AS_PATH is a well-known mandatory attribute. This attribute identifies the autonomous
systems through which routing information carried in this Update message has passed.
When a route is advertised from the local AS to another AS, each passed AS number is
added into the AS_PATH attribute, thus the receiver can determine ASs to route the
massage back. The number of the AS closest to the receiver's AS is leftmost, as shown
below:
Name
5-6
Chapter 5 BGP Configuration
Category
Optional transitive
Optional transitive
Optional non-transitive
Optional non-transitive
Optional non-transitive