rfc9494v4.txt | rfc9494.txt | |||
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skipping to change at line 82 ¶ | skipping to change at line 82 ¶ | |||
3.1. Long-Lived Graceful Restart Capability | 3.1. Long-Lived Graceful Restart Capability | |||
3.2. LLGR_STALE Community | 3.2. LLGR_STALE Community | |||
3.3. NO_LLGR Community | 3.3. NO_LLGR Community | |||
4. Theory of Operation | 4. Theory of Operation | |||
4.1. Use of the Graceful Restart Capability | 4.1. Use of the Graceful Restart Capability | |||
4.2. Session Resets | 4.2. Session Resets | |||
4.3. Processing LLGR_STALE Routes | 4.3. Processing LLGR_STALE Routes | |||
4.4. Route Selection | 4.4. Route Selection | |||
4.5. Errors | 4.5. Errors | |||
4.6. Optional Partial Deployment Procedure | 4.6. Optional Partial Deployment Procedure | |||
4.7. Procedures: BGP Is the PE-CE Protocol in a VPN | 4.7. Procedures When BGP Is the PE-CE Protocol in a VPN | |||
4.7.1. Procedures: EBGP Is the PE-CE Protocol in a VPN | 4.7.1. Procedures When EBGP Is the PE-CE Protocol in a VPN | |||
4.7.2. Procedures: IBGP Is the PE-CE Protocol in a VPN | 4.7.2. Procedures When IBGP Is the PE-CE Protocol in a VPN | |||
5. Deployment Considerations | 5. Deployment Considerations | |||
5.1. When BGP Is the PE-CE Protocol in a VPN | 5.1. When BGP Is the PE-CE Protocol in a VPN | |||
5.2. Risks of Depreferencing Routes | 5.2. Risks of Depreferencing Routes | |||
6. Security Considerations | 6. Security Considerations | |||
7. Examples of Operation | 7. Examples of Operation | |||
8. IANA Considerations | 8. IANA Considerations | |||
9. References | 9. References | |||
9.1. Normative References | 9.1. Normative References | |||
9.2. Informative References | 9.2. Informative References | |||
Acknowledgements | Acknowledgements | |||
skipping to change at line 535 ¶ | skipping to change at line 535 ¶ | |||
If this strategy for partial deployment is used, the network operator | If this strategy for partial deployment is used, the network operator | |||
should set the LOCAL_PREF to zero for all long-lived stale routes | should set the LOCAL_PREF to zero for all long-lived stale routes | |||
throughout the Autonomous System. This trades off a small reduction | throughout the Autonomous System. This trades off a small reduction | |||
in flexibility (ordering may not be preserved between competing long- | in flexibility (ordering may not be preserved between competing long- | |||
lived stale routes) for consistency between routers that do, and do | lived stale routes) for consistency between routers that do, and do | |||
not, support this specification. Since the consistency of route | not, support this specification. Since the consistency of route | |||
selection can be important for preventing forwarding loops, the | selection can be important for preventing forwarding loops, the | |||
latter consideration dominates. | latter consideration dominates. | |||
4.7. Procedures: BGP Is the PE-CE Protocol in a VPN | 4.7. Procedures When BGP Is the PE-CE Protocol in a VPN | |||
4.7.1. Procedures: EBGP Is the PE-CE Protocol in a VPN | 4.7.1. Procedures When EBGP Is the PE-CE Protocol in a VPN | |||
In VPN deployments (for example, [RFC4364]), External BGP (EBGP) is | In VPN deployments (for example, [RFC4364]), External BGP (EBGP) is | |||
often used as a PE-CE protocol. It may be a practical necessity in | often used as a PE-CE protocol. It may be a practical necessity in | |||
such deployments to accommodate interoperation with peer routers that | such deployments to accommodate interoperation with peer routers that | |||
cannot easily be upgraded to support specifications such as this one. | cannot easily be upgraded to support specifications such as this one. | |||
This leads to a problem: the procedures defined elsewhere in this | This leads to a problem: the procedures defined elsewhere in this | |||
document generally prevent LLGR stale routes from being sent across | document generally prevent LLGR stale routes from being sent across | |||
EBGP sessions that don't support LLGR, but this could prevent the VPN | EBGP sessions that don't support LLGR, but this could prevent the VPN | |||
routes from being used for their intended purpose. | routes from being used for their intended purpose. | |||
skipping to change at line 566 ¶ | skipping to change at line 566 ¶ | |||
continue to apply. Finally, if this exception is used, the | continue to apply. Finally, if this exception is used, the | |||
implementation SHOULD, by default, attach the NO_EXPORT community to | implementation SHOULD, by default, attach the NO_EXPORT community to | |||
the routes in question, as an additional protection against stale | the routes in question, as an additional protection against stale | |||
routes spreading without limit. Attachment of the NO_EXPORT | routes spreading without limit. Attachment of the NO_EXPORT | |||
community MAY be disabled by explicit configuration in order to | community MAY be disabled by explicit configuration in order to | |||
accommodate exceptional cases. | accommodate exceptional cases. | |||
See further discussion of using an explicitly configured policy to | See further discussion of using an explicitly configured policy to | |||
mitigate this issue in Section 5.1. | mitigate this issue in Section 5.1. | |||
4.7.2. Procedures: IBGP Is the PE-CE Protocol in a VPN | 4.7.2. Procedures When IBGP Is the PE-CE Protocol in a VPN | |||
If IBGP is used as the PE-CE protocol, following the procedures of | If IBGP is used as the PE-CE protocol, following the procedures of | |||
[RFC6368], then when a PE router imports a VPN route that contains | [RFC6368], then when a PE router imports a VPN route that contains | |||
the ATTR_SET attribute into a destination VRF and subsequently | the ATTR_SET attribute into a destination VRF and subsequently | |||
advertises that route to a CE router: | advertises that route to a CE router: | |||
* If the CE router supports the procedures of this document (in | * If the CE router supports the procedures of this document (in | |||
other words, if the CE router has advertised the LLGR Capability): | other words, if the CE router has advertised the LLGR Capability): | |||
In addition to including the path attributes derived from the | In addition to including the path attributes derived from the | |||
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