autonomous system
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... BGP systems. This network
reachability information includes information on the list of
Autonomous Systems (ASs) that reachability information traverses.
This information is sufficient to construct a graph of AS
connectivity ...
...
This document uses the term `Autonomous System' (AS) throughout. The
classic definition of an Autonomous System ...
... Autonomous System' (AS) throughout. The
classic definition of an Autonomous System is a set of routers under
a single technical administration, using an interior gateway protocol ...
... interior gateway protocols and sometimes several
sets of metrics within an AS. The use of the term Autonomous System
here stresses the fact that, even when multiple IGPs and metrics are
...
... BGP to exchange routing information with a border
router in another Autonomous System. The implications and
applications of this architecture are for further study.
...
... Version |
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| My Autonomous System |
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| Hold Time ...
... BGP
peers. The information in the UPDATE packet can be used to construct
a graph describing the relationships of the various Autonomous
Systems. By applying rules to be discussed, routing information
loops and some other anomalies may be detected and removed from
...
... be used by a BGP speaker's decision process to discriminate
among multiple exit points to a neighboring autonomous
system.
Its usage is defined in 5.1.4.
...
... BGP speaker
to inform other BGP speakers in its own autonomous system of
the originating speaker's degree of preference for an
advertised route ...
... well-known mandatory attribute. The ORIGIN attribute
shall be generated by the autonomous system that originates the
associated routing information. It shall be included in the UPDATE
messages ...
... PATH is a well-known mandatory attribute. This attribute
identifies the autonomous systems through which routing information
carried in this UPDATE message ...
... BGP speaker advertises the route to another BGP
speaker located in its own autonomous system, the advertising
speaker shall not modify the AS_PATH attribute ...
... route to a BGP speaker
located in a neighboring autonomous system, then the advertising
speaker shall update the AS ...
... PATH attribute of all UPDATE messages sent to BGP
speakers located in neighboring autonomous systems. (In this
case, the AS number of the originating speaker's autonomous
system ...
... autonomous systems. (In this
case, the AS number of the originating speaker's autonomous
system will be the only entry in the AS_PATH attribute).
...
... UPDATE messages sent to BGP speakers located
in its own autonomous system. (An empty AS_PATH attribute is
...
... route to a BGP speaker located in
its own autonomous system, the advertising speaker shall not modify
the NEXT_HOP attribute associated with the route ...
... BGP speaker sends to the
other BGP speakers located in its own autonomous system. A BGP
speaker shall calculate the degree of preference for each external
route ...
... UPDATE messages
that it sends to BGP speakers located in a neighboring autonomous
system. If it is contained in an UPDATE message that is received from
a BGP speaker ...
... UPDATE message that is received from
a BGP speaker which is not located in the same autonomous system as
the receiving speaker, then this attribute shall be ignored by the
...
... Error Subcode is set to Bad Peer AS. The determination of
acceptable Autonomous System numbers is outside the scope of this
protocol.
...
... KeepAlive timers are not started. If the value of
the Autonomous System field is the same as the local Autonomous
System number, then the connection is an "internal" connection ...
... timers are not started. If the value of
the Autonomous System field is the same as the local Autonomous
System number, then the connection is an "internal" connection;
...
... - selection of routes to be advertised to BGP speakers located in
the local speaker's autonomous system
- selection of routes to be advertised to BGP speakers ...
... - selection of routes to be advertised to BGP speakers located in
neighboring autonomous systems
- route ...
... route received from a BGP speaker located in a
neighboring autonomous system, and for advertising to the other
BGP speakers in the local autonomous system ...
... autonomous system, and for advertising to the other
BGP speakers in the local autonomous system the routes that have
the highest degree of preference for each distinct destination.
...
... responsible for disseminating routes in the Loc-RIB to each peer
located in a neighboring autonomous system, according to the
policies contained in the PIB. Route aggregation ...
... BGP
speaker receives an UPDATE message from a peer located in a
neighboring autonomous system that advertises a new route, a
replacement route ...
... route is
learned from a BGP speaker in the local autonomous system, either the
value of the LOCAL_PREF attribute shall be taken as the degree of
...
... the route is learned from a BGP speaker in a neighboring autonomous
system, then the degree of preference shall be computed based on
preconfigured policy information. The exact nature of this policy
information and the computation involved is a local matter. The
...
... Adj-RIBs-In, including those received
from BGP speakers located in its own autonomous system and those
received from BGP speakers located in neighboring autonomous systems ...
... autonomous system and those
received from BGP speakers located in neighboring autonomous systems.
...
... preferable routes, both those received from BGP speakers located in
neighboring autonomous systems, and those received from other BGP
speakers located in the local speaker's autonomous system.
...
... neighboring autonomous systems, and those received from other BGP
speakers located in the local speaker's autonomous system.
...
... route all the BGP speakers within an autonomous system can ascertain
the cost of a path (interior distance) to the address depicted by the
...
... candidate routes was advertised by the
BGP speaker in a neighboring autonomous system, select the
route that was advertised by the BGP speaker ...
... route that was advertised by the BGP speaker in a neighboring
autonomous system whose BGP Identifier has the lowest value
among all other BGP speakers ...
... BGP Identifier has the lowest value
among all other BGP speakers in neighboring autonomous systems;
- otherwise, select the route ...
... by the Decision Process to other BGP speakers which may be located in
either the same autonomous system or a neighboring autonomous system.
rules for information exchange ...
... BGP speakers which may be located in
either the same autonomous system or a neighboring autonomous system.
rules for information exchange between BGP speakers ...
... information exchange between BGP speakers located in
different autonomous systems are given in 9.2.2; rules for
information exchange between BGP speakers ...
... information exchange between BGP speakers located in the same
autonomous system are given in 9.2.1.
...
... routing information between a set of BGP speakers,
all of which are located in the same autonomous system, is referred
to as internal distribution.
...
... BGP speaker receives an UPDATE message from another BGP
speaker located in its own autonomous system, the receiving BGP
speaker shall not re-distribute the routing information ...
... route from a BGP speaker in a
neighboring autonomous system, it shall advertise that route to all
other BGP speakers ...
... route to all
other BGP speakers in its autonomous system by means of an UPDATE
message if any of the following conditions occur:
...
... that the local speaker has assigned to other routes that have been
received from BGP speakers in neighboring autonomous systems, or
2) there are no other routes that have been received from BGP
speakers ...
...
2) there are no other routes that have been received from BGP
speakers in neighboring autonomous systems, or
3) the newly received route ...
... connections to several BGP speakers in
neighboring autonomous systems, there will be multiple Adj-RIBs-In
associated with these peers. These Adj-RIBs-In ...
... destination, all of which were
advertised by BGP speakers located in neighboring autonomous systems.
The local BGP speaker shall select one of these routes according to
...
... routing information to BGP speakers located in neighboring autonomous
systems. As part of Phase 3 route selection process, the BGP speaker
...
... route shall be advertised to BGP speakers located in
neighboring autonomous systems by means of UPDATE message.
...
... removed.
Changes to the reachable destinations within its own autonomous
system shall also be advertised in an UPDATE message.
...
... feasible routes to some common set of destinations received from BGP
speakers in neighboring autonomous systems must be separated by at
least MinRouteAdvertisementInterval. Clearly, this can only be
...
... of destinations received from BGP speakers in neighboring autonomous
systems will be at least MinRouteAdvertisementInterval, and will also
ensure a constant upper bound on the interval is acceptable.
...
...
Since fast convergence is needed within an autonomous system, this
procedure does not apply for routes receives from other BGP speakers
...
... procedure does not apply for routes receives from other BGP speakers
in the same autonomous system. To avoid long-lived black holes, the
procedure does not apply to the explicit withdrawal of unfeasible
...
... UPDATE
messages that report changes within the advertising BGP speaker's own
autonomous systems.
...
... IP address
prefixes. In cases where there is a correspondence between the
address structure and the systems under control of an autonomous
system administrator, it will be possible to reduce the size of
the NLRI ...
... NLRI can be
reached through paths that traverse at least some of the
constituent autonomous systems. AS_SETs provide sufficient
information to avoid routing information ...
... IP
packet arrives at the edge of a group of autonomous systems, the
BGP speaker at that point is likely to have more detailed path
...