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Network Working Group                                          A. LindemRequest for Comments: 4167                            Cisco Systems, IncCategory: Informational                                     October 2005Graceful OSPF Restart Implementation ReportStatus of This Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2005).Abstract   Graceful OSPF Restart, as specified inRFC 3623, provides a mechanism   whereby an OSPF router can stay on the forwarding path even as its   OSPF software is restarted.  This document provides an implementation   report for this extension to the base OSPF protocol.Table of Contents1. Overview ........................................................22. Implementation Experience .......................................22.1. Implementation Differences .................................23. MIB Reference ...................................................34. Authentication Mechanisms .......................................35. List of Implementations .........................................36. Test Scenarios ..................................................37. Operational Experience ..........................................48. Security Considerations .........................................49. Normative References ............................................410. Informative References .........................................411. Acknowledgments ................................................5Lindem                       Informational                      [Page 1]

RFC 4167      Graceful OSPF Restart Implementation Report   October 20051.  Overview   Today, many Internet routers implement a separation of control and   forwarding functions.  Certain processors are dedicated to control   and management tasks such as OSPF routing, while other processors   perform the data forwarding tasks.  This separation creates the   possibility of maintaining a router's data forwarding capability   while the router's control software is restarted/reloaded.  For the   OSPF protocol [OSPF], the protocol mechanisms necessary to accomplish   this are described in Graceful OSPF Restart [GRACE].   This document satisfies theRFC 1264 [CRITERIA] requirement for a   report on implementation experience for Graceful OSPF Restart.Section 2 of this document contains the results of an implementation   survey.  It also documents implementation differences between the   vendors responding to the survey.Section 3 contains a MIB   reference.Section 4 provide an authentication reference.Section 5   simply refers to the implementations listed insection 2.Section 6   includes a minimal set of test scenarios.  Finally,section 7   includes a disclaimer with respect to operational experience.2.  Implementation Experience   Eleven vendors have implemented graceful OSPF and have completed the   implementation survey.  These include Redback, Juniper, Motorola   Computer Group (formerly Netplane Systems), Mahi Networks, Nexthop   technologies, Force10 Networks, Procket, Alcatel, Laurel Networks,   DCL (Data Connection Limited), and Ericsson.  All have implemented   restart from the perspective of both a restarting and helper router.   All but one vendor implemented both planned and unplanned restart.   All implementations are original.  Seven successfully tested   interoperability with Juniper.  Juniper successfully tested   interoperability with Force10 Networks.  One vendor tested with John   Moy's GNU Public License implementation [OSPFD].  Two vendors had not   tested interoperability at the time of the survey.2.1.  Implementation Differences   The first difference was whether strict LSA checking was implemented   and, if so, whether it was configurable.  In the context of graceful   OSPF restart, strict LSA checking indicates whether a changed LSA   will result in the termination of graceful restart by a helping   router.  Four vendors made it configurable (three defaulted it to   enabled and one to disabled), another made it a compile option   (shipping with strict LSA checking disabled), another didn't   implement it at all, and five implemented strict LSA checking with no   configuration option to disable it.Lindem                       Informational                      [Page 2]

RFC 4167      Graceful OSPF Restart Implementation Report   October 2005   The second was whether a received grace LSA would be taken to apply   only to the adjacency on which it was received or to all adjacencies   with the restarting router.  This is a rather subtle difference since   it only applies to helping and restarting routers with more than one   full adjacency at the time of restart.  Eight vendors implemented the   option of the received grace LSA only applying to the adjacency on   which it was received.  Three vendors applied the grace LSA to all   adjacencies with the grace LSA originator (i.e., the restarting   router).   The final difference was in whether additional extensions were   implemented to accommodate other features such as protocol   redistribution or interaction with MPLS VPNs [VPN].  Five vendors   implemented extensions and six did not.  It should be noted that such   extensions are beyond the scope of Graceful OSPF Restart [GRACE].3.  MIB Reference   MIB objects for the Graceful OSPF Restart have been added to the OSPF   Version 2 Management Information Base [OSPFMIB].  Additions include:   -  Objects ospfRestartSupport, ospfRestartInterval, ospfRestartAge,      ospfRestartExitReason, and ospfRestartStrictLsaChecking to      ospfGeneralGroup.   -  Objects ospfNbrRestartHelperStatus, ospfNbrRestartHelperAge, and      ospfNbrRestartHelperExitReason to ospfNbrEntry.   -  Objects ospfVirtNbrRestartHelperStatus,      ospfVirtNbrRestartHelperAge, and      ospfVirtNbrRestartHelperExitReason to ospfVirtNbrEntry.4.  Authentication Mechanisms   The authentication mechanisms are the same as those implemented by   the base OSPF protocol [OSPF].5.  List of Implementations   Refer tosection 2.6.  Test Scenarios   A router implementing graceful restart should test, at a minimum, the   following scenarios as both a restarting and helping router.  For all   scenarios, monitoring data plane traffic may be used to ensure that   the restart is non-disruptive:Lindem                       Informational                      [Page 3]

RFC 4167      Graceful OSPF Restart Implementation Report   October 2005   1. Operation over a broadcast network.   2. Operation over a P2P network.   3. Operation over a virtual link.   4. Operation using OSPF MD5 authentication.   5. Early graceful restart termination when an LSA inconsistency is      detected.   6. Early graceful restart termination when a flooded LSA changes (if      implemented).7.  Operational Experience   Since OSPF graceful restart is configurable, it is difficult to gage   operational experience at this juncture.  However, multiple service   providers have tested and evaluated it.8.  Security Considerations   This document does not discuss implementation and interoperability   aspects of the security mechanisms in great detail, as no new   security mechanisms are introduced with Graceful OSPF Restart.   Security considerations for the OSPF protocol are included inRFC2328 [OSPF].  Security considerations for Graceful OSPF Restart are   included in [GRACE].9.  Normative References   [OSPF]      Moy, J., "OSPF Version 2", STD 54,RFC 2328, April 1998.   [GRACE]     Moy, J., Pillay-Esnault, P., and A. Lindem, "Graceful               OSPF Restart",RFC 3623, November 2003.   [CRITERIA]  Hinden, R., "Internet Engineering Task Force Internet               Routing Protocol Standardization Criteria",RFC 1264,               October 1991.10.  Informative References   [VPN]       Rosen, E. and Y Rekhter,"BGP/MPLS IP VPNs", Work in               Progress, September 2003.   [OSPFD]     Moy, J., "OSPF Complete Implementation", Addison-Wesley,               1991, ISBN 0-201-30966-1Lindem                       Informational                      [Page 4]

RFC 4167      Graceful OSPF Restart Implementation Report   October 2005   [OSPFMIB]   Joyal, D., et al, "OSPF Version 2 Management Information               Base", Work in Progress, December 2003.11.  Acknowledgments   The author wishes to acknowledge the individuals/vendors who have   completed the implementation survey.      - Anand Oswal (Redback Networks)      - Padma Pillay-Esnault (Juniper Networks)      - Vishwas Manral (Motorola Computer Group, formerly Netplane        System).      - Sriganesh Kini (Mahi Networks)      - Jason Chen (Force10 Networks)      - Daniel Gryniewicz (NextHop Technologies)      - Hasmit Grover (Procket Networks)      - Pramoda Nallur (Alcatel)      - Ardas Cilingiroglu (Laurel Networks)      - Philip Crocker (Data Connection Limited)      - Le-Vinh Hoang (Ericsson)Author's Address   Acee Lindem   Cisco Systems, Inc   7025 Kit Creek Road   Research Triangle Park, NC  27709   USA   EMail: acee@cisco.comLindem                       Informational                      [Page 5]

RFC 4167      Graceful OSPF Restart Implementation Report   October 2005Full Copyright Statement   Copyright (C) The Internet Society (2005).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at ietf-   ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Lindem                       Informational                      [Page 6]