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Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: For this we propose, if no OSPF control packets were received within the dead interval on a link in Area 1 as per the above network scenario, Router2 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. (Using the creation date from RFC3623, updated by this document, for RFC5378 checks: 2001-02-20) -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (July 7, 2019) is 1753 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Missing Reference: 'RFC2119' is mentioned on line 85, but not defined == Unused Reference: 'KEYWORDS' is defined on line 145, but no explicit reference was found in the text == Unused Reference: 'RFC3623' is defined on line 148, but no explicit reference was found in the text == Unused Reference: 'RFC5187' is defined on line 151, but no explicit reference was found in the text == Unused Reference: 'RFC2328' is defined on line 156, but no explicit reference was found in the text Summary: 0 errors (**), 0 flaws (~~), 7 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 INTERNET-DRAFT Vijayalaxmi Basavaraj 3 Intended Status: Informational Ankur Dubey 4 Updates: 3623, 5187 Sami Boutros 5 VMware 7 Acee Lindem 8 Cisco 9 Expires: January 8, 2020 July 7, 2019 11 OSPF Graceful Restart Enhancements 12 draft-basavaraj-ospf-graceful-restart-enhancements-01 14 Abstract 16 This document describes enhancements to the OSPF graceful restart 17 procedures to improve routing convergence in some OSPF network 18 deployments. This document updates RFC 3623 and RFC 5187. 20 Status of this Memo 22 This Internet-Draft is submitted to IETF in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF), its areas, and its working groups. Note that 27 other groups may also distribute working documents as 28 Internet-Drafts. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 The list of current Internet-Drafts can be accessed at 36 http://www.ietf.org/1id-abstracts.html 38 The list of Internet-Draft Shadow Directories can be accessed at 39 http://www.ietf.org/shadow.html 41 Copyright and License Notice 43 Copyright (c) 2019 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 60 2 Graceful Restart Enhancements . . . . . . . . . . . . . . . . . 3 61 2.1 Stub Link Network Scenarios . . . . . . . . . . . . . . . . 3 62 2.2 Multiple Failure Scenarios . . . . . . . . . . . . . . . . . 4 63 3 Security Considerations . . . . . . . . . . . . . . . . . . . . 4 64 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 65 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4 66 5.1 Normative References . . . . . . . . . . . . . . . . . . . 4 67 5.2 Informative References . . . . . . . . . . . . . . . . . . 4 68 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 5 70 1 Introduction 72 This document describes the enhancements to the current Graceful 73 restart OSPF procedure to improve routing convergence in certain OSPF 74 network deployment scenarios. The goal is for both the restarting 75 OSPF node and the helper OSPF node to terminate the OSPF graceful 76 restart procedure faster and not wait for the grace period expiry in 77 those network scenarios and hence improve the overall OSPF network 78 convergence. 80 1.1 Terminology 82 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 83 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 84 document are to be interpreted as described in RFC 2119 [RFC2119]. 86 2 Graceful Restart Enhancements 88 In this section we will describe couple of issues with OSPF Graceful 89 Restart (GR) in some network deployment scenarios, and a proposal to 90 enhance the OSPF GR procedure to achieve faster OSPF routing 91 convergence in those scenarios. 93 2.1 Stub Link Network Scenarios 95 --------- --------- --------- 96 |Router1|---Area 0----|Router2|---Area 1---|Router3| 97 --------- --------- --------- 99 Figure1: OSPF topology with Graceful restart 101 As described in figure 1, Router2 is an area border router (ABR) with 102 OSPF links in 2 areas. Furthermore. Router2 has formed full 103 adjacencies only in Area 0. In Area 1, Router2 has an OSPF link 104 enabled but Router2 couldn't form any adjacency either because 105 Router3 is down or Router3 does not have OSPF enabled. Hence, Router2 106 will only have a stub link in Area 1. 108 On restart, the ABR router Router2, having only a stub link in the 109 Area 1, will never receive its pre-restart LSA in this area and will 110 never form an adjacency, Router2 will have to wait for the grace 111 period expiry leading to slower OSPF routing convergence. 113 For this we propose, if no OSPF control packets were received within 114 the dead interval on a link in Area 1 as per the above network 115 scenario, Router2 MUST mark the link as stub and MUST not wait for 116 the grace period to form an adjacency on this link to successfully 117 Exit GR. 119 2.2 Multiple Failure Scenarios 121 In scenarios where more than one router is restarting at the same 122 time in the same OSPF area and StrictLSAChecking is disabled, 123 restarting OSPF routers will end up waiting the entire grace interval 124 to exit GR. 126 If the restarting routers receive a Grace Link State Advertisements 127 (LSA) from another router in a given area after restart, and the 128 helper routers receive grace LSAs from more than one router, this 129 will indicate that there have been multiple failures. Therefore, the 130 helper and restarting routers MUST terminate GR and avoid any 131 unnecessary delay in OSPF routing convergence. 133 3 Security Considerations 135 This document does not introduce any additional security constraints. 137 4. IANA Considerations 139 None 141 5. References 143 5.1 Normative References 145 [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate 146 Requirement Levels", BCP 14, RFC 2119, March 1997. 148 [RFC3623] Moy, J., Pillay-Esnault, P., and A. Lindem, "Graceful OSPF 149 Restart", RFC 3623, November 2003. 151 [RFC5187] Pillay-Esnault, P., and A. Lindem, "OSPFv3 Graceful 152 Restart", RFC 5187, June 2008. 154 5.2 Informative References 156 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 158 Authors' Addresses 160 Sami Boutros 161 VMware 162 Email: boutross@vmware.com 164 Ankur Dubey 165 VMware 166 Email: adubey@vmware.com 168 Vijayalaxmi Basavaraj 169 VMware 170 Email: vbasavaraj@vmware.com 172 Acee Lindem 173 Cisco 174 Email: acee@cisco.com