idnits 2.17.1 draft-basavaraj-lsr-ospf-gr-enhancements-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- -- The abstract seems to indicate that this document updates RFC3623, but the header doesn't have an 'Updates:' line to match this. -- The abstract seems to indicate that this document updates RFC5187, but the header doesn't have an 'Updates:' line to match this. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: For this scenario, if no OSPF control packets are received within the dead interval on a link in Area 1 as per the above network scenario, Router-2 MUST mark the link as stub and MUST not wait for the grace period to form an adjacency on this link to successfully Exit GR. -- The document date (December 27, 2020) is 1188 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 LSR Working Group S. Boutros 3 Internet-Draft A. Dubey 4 Intended status: Standards Track V. Basavaraj 5 Expires: June 30, 2021 VMware 6 A. Lindem 7 Cisco Systems 8 December 27, 2020 10 OSPF Graceful Restart Enhancements 11 draft-basavaraj-lsr-ospf-gr-enhancements-02 13 Abstract 15 This document describes enhancements to the OSPF graceful restart 16 procedures to improve routing convergence in some OSPF network 17 deployments. This document updates RFC 3623 and RFC 5187. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on June 30, 2021. 36 Copyright Notice 38 Copyright (c) 2020 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 2. Conventions used in this document . . . . . . . . . . . . . . 2 55 3. Graceful Restart Enhancements . . . . . . . . . . . . . . . . 2 56 3.1. Stub-Link Network Scenarios . . . . . . . . . . . . . . . 2 57 3.2. Multiple Failure Scenarios . . . . . . . . . . . . . . . 3 58 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 59 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 60 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3 61 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 63 7.2. Informative References . . . . . . . . . . . . . . . . . 4 64 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4 66 1. Introduction 68 This document describes the enhancements to the current OSPF 69 [RFC2328] and OSPFv3 [RFC5340] graceful restart procedures as 70 respectively defined in OSPF Graceful Restart [RFC3623] and OSPFv3 71 Graceful Restart [RFC5187] to improve routing convergence in certain 72 OSPF network deployment scenarios. The goal is for both the 73 restarting OSPF node and the helper OSPF node to terminate the OSPF 74 graceful restart procedure faster and not wait for the grace period 75 expiry in those network scenarios and hence improve the overall OSPF 76 network convergence. 78 2. Conventions used in this document 80 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 81 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 82 "OPTIONAL" in this document are to be interpreted as described in BCP 83 14 [RFC2119] [RFC8174] when, and only when, they appear in all 84 capitals, as shown here. 86 3. Graceful Restart Enhancements 88 3.1. Stub-Link Network Scenarios 90 +--------+ +--------+ +--------+ 91 |Router-1|---Area 0----|Router-2|---Area 1---|Router-3| 92 +------=-+ +--------+ +--------+ 94 Figure 1: OSPF topology with Graceful Restart 96 As graphically depicted in figure 1, Router-2 is an area border 97 router (ABR) with OSPF links in 2 areas. Furthermore, Router-2 has 98 formed full adjacencies only in Area 0. In Area 1, Router-2 has an 99 OSPF link enabled but Router2 could not form an adjacency either 100 because Router-3 is down or Router-3 does not have OSPF enabled. 101 Hence, Router-2 will only have a stub link in Area 1. 103 On restart, the ABR router Router-2, having only a stub link in the 104 Area 1, will never receive its pre-restart LSA in this area and will 105 never form an adjacency and will have to wait for the grace period 106 expiry leading to slower OSPF routing convergence. 108 For this scenario, if no OSPF control packets are received within the 109 dead interval on a link in Area 1 as per the above network scenario, 110 Router-2 MUST mark the link as stub and MUST not wait for the grace 111 period to form an adjacency on this link to successfully Exit GR. 113 3.2. Multiple Failure Scenarios 115 In scenarios where more than one router is restarting at the same 116 time in the same OSPF area and StrictLSAChecking is disabled, 117 restarting OSPF routers will end up waiting the entire grace interval 118 to exit GR. If the restarting routers receive a Grace Link State 119 Advertisement (LSA) from another router in a given area after 120 restart, and the helper routers receive grace LSAs from more than one 121 router, this will indicate that there have been multiple failures. 122 Therefore, the helper and restarting routers MUST terminate GR and 123 avoid any unnecessary delay in OSPF routing convergence. 125 4. Security Considerations 127 The security considerations in OSPF Graceful Restart [RFC3623] and 128 OSPFv3 Graceful Restart [RFC5187] are applicable. This document does 129 not introduce any additional security considerations. 131 5. IANA Considerations 133 This specification doesn not require any IANA assignments. 135 6. Acknowledgements 137 TBD 139 7. References 140 7.1. Normative References 142 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 143 Requirement Levels", BCP 14, RFC 2119, 144 DOI 10.17487/RFC2119, March 1997, 145 . 147 [RFC3623] Moy, J., Pillay-Esnault, P., and A. Lindem, "Graceful OSPF 148 Restart", RFC 3623, DOI 10.17487/RFC3623, November 2003, 149 . 151 [RFC5187] Pillay-Esnault, P. and A. Lindem, "OSPFv3 Graceful 152 Restart", RFC 5187, DOI 10.17487/RFC5187, June 2008, 153 . 155 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 156 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 157 May 2017, . 159 7.2. Informative References 161 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 162 DOI 10.17487/RFC2328, April 1998, 163 . 165 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 166 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 167 . 169 Authors' Addresses 171 Sami Boutros 172 VMware 174 Email: sboutros@vmware.com 176 Ankur Dubey 177 VMware 179 Email: adubey@vmware.com 181 Vijayalaxmi Basavaraj 182 VMware 184 Email: vbasavaraj@vmware.com 185 Acee Lindem 186 Cisco Systems 187 301 Midenhall Way 188 Cary, NC 27513 189 USA 191 Email: acee@cisco.com