idnits 2.17.1 draft-xu-isis-flooding-reduction-in-msdc-00.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 : ---------------------------------------------------------------------------- ** There is 1 instance of too long lines in the document, the longest one being 1 character in excess of 72. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (January 6, 2017) is 2664 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC4136' is defined on line 216, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group X. Xu 3 Internet-Draft Huawei 4 Intended status: Standards Track January 6, 2017 5 Expires: July 10, 2017 7 IS-IS Flooding Reduction in MSDC 8 draft-xu-isis-flooding-reduction-in-msdc-00 10 Abstract 12 IS-IS is commonly used as a underlay routing protocol for MSDC 13 (Massively Scalable Data Center) networks. This document proposes 14 some extensions to IS-IS so as to reduce the IS-IS flooding within 15 MSDC networks greatly. The reduction of the IS-IS flooding is much 16 beneficial to improve the scalability of MSDC networks. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on July 10, 2017. 35 Copyright Notice 37 Copyright (c) 2017 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 54 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 3. Modifications to Current IS-IS Behaviors . . . . . . . . . . 4 56 3.1. IS-IS Routers as Non-DIS . . . . . . . . . . . . . . . . 4 57 3.2. Controllers as DIS . . . . . . . . . . . . . . . . . . . 5 58 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 59 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 60 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 61 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 63 7.2. Informative References . . . . . . . . . . . . . . . . . 5 64 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 66 1. Introduction 68 IS-IS is commonly used as a underlay routing protocol for Massively 69 Scalable Data Center (MSDC) networks. In addition, centrolized 70 controllers are becoming fundamental network elements in most MSDCs. 71 One or more controllers are usually connected to all routers within 72 the MSDC network via a Local Area Network (LAN) which is dedicated 73 for network management purpose (called management LAN), as shown in 74 Figure 1. 76 +----------+ +----------+ 77 |Controller| |Controller| 78 +----+-----+ +-----+----+ 79 |DIS |Candidate DIS 80 | | 81 | | 82 ---+---------+---+----------+-----------+---+---------+-Management LAN 83 | | | | | 84 |Non-DIS |Non-DIS |Non-DIS |Non-DIS |Non-DIS 85 | | | | | 86 | +---+--+ | +---+--+ | 87 | |Router| | |Router| | 88 | *------*- | /*---/--* | 89 | / \ -- | // / \ | 90 | / \ -- | // / \ | 91 | / \ --|// / \ | 92 | / \ /*- / \ | 93 | / \ // | -- / \ | 94 | / \ // | -- / \ | 95 | / /X | -- \ | 96 | / // \ | / -- \ | 97 | / // \ | / -- \ | 98 | / // \ | / -- \ | 99 | / // \ | / -- \ | 100 | / // \ | / -- \ | 101 | / // \ | / -- \ | 102 +-+- //* +\\+-/-+ +---\-++ 103 |Router| |Router| |Router| 104 +------+ +------+ +------+ 106 Figure 1 108 With the assistance of a controller acting as IS-IS Designated 109 Intermediate System (DIS) for the management LAN, IS-IS routers 110 within the MSDC network don't need to exchange any IS-IS Protocl 111 Datagram Units (PDUs) other than Hello packets among them. In order 112 to obtain the full topology information (i.e., the fully synchronized 113 link-state database) of the MSDC's network, these IS-IS routers would 114 exchange the link-state information with the controller being elected 115 as IS-IS DIS for the management LAN instead. 117 To further suppress the flooding of multicast IS-IS PDUs originated 118 from IS-IS routers over the management LAN, IS-IS routers would not 119 send multicast IS-IS Hello packets over the management LAN. 120 Insteads, they just wait for IS-IS Hello packets originated from the 121 controller being elected as IS-IS DIS initially. Once an IS-IS DIS 122 for the management LAN has been discovered, they start to send IS-IS 123 Hello packets directly (as unicasts) to the IS-IS DIS periodically. 125 In addition, IS-IS routers would send IS-IS PDUs to the IS-IS DIS for 126 the management LAN as unicasts as well. In contrast, the controller 127 being elected as IS-IS DIS would send IS-IS PDUs as before. As a 128 result, IS-IS routers would not receive IS-IS PDUs from one another 129 unless these IS-IS PDUs are forwarded as unknown unicasts over the 130 management LAN. Through the above modifications to the current IS-IS 131 router behaviors, the IS-IS flooding is greatly reduced which is much 132 beneficial to improve the scalability of MSDC networks. 134 1.1. Requirements Language 136 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 137 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 138 document are to be interpreted as described in RFC 2119 [RFC2119]. 140 2. Terminology 142 This memo makes use of the terms defined in [RFC1195]. 144 3. Modifications to Current IS-IS Behaviors 146 3.1. IS-IS Routers as Non-DIS 148 After the bidirectional exchange of IS-IS Hello packets among IS-IS 149 routers, IS-IS routers would originate Link State PDUs (LSPs) 150 accordingly. However, these self-originated LSPs need not to be 151 exchanged directly among them anymore. Instead, these LSPs just need 152 to be sent solely to the controller being elected as IS-IS DIS for 153 the management LAN. 155 To further reduce the flood of multicast IS-IS PDUs over the 156 management LAN, IS-IS routers SHOULD send IS-IS PDUs as unicasts. 157 More specifically, IS-IS routers SHOULD send unicast IS-IS Hello 158 packets periodically to the controller being elected as IS-IS DIS. 159 In other words, IS-IS routers would not send any IS-IS Hello packet 160 over the management LAN until they have found an IS-IS DIS for the 161 management LAN. Note that IS-IS routers SHOULD NOT be elected as IS- 162 IS DIS for the management LAN (This is done by setting the DIS 163 Priority of those IS-IS routers to zero). As a result, IS-IS routers 164 would not see each other over the management LAN. In other word, IS- 165 IS routers would not establish adjacencies with one other. 166 Furthermore, IS-IS routers SHOULD send all the types of IS-IS PDUs to 167 the controller being elected as IS-IS DIS as unicasts as well. 169 To advoid the data traffic from being forwarded across the management 170 LAN, the cost of all IS-IS routers' interfaces to the management LAN 171 SHOULD be set to the maximum value. 173 3.2. Controllers as DIS 175 The controller being elected as IS-IS DIS would send IS-IS PDUs as 176 multicasts or unicasts as before. And it SHOULD accept and process 177 those unicast IS-IS PDUs originated from IS-IS routers. Upon 178 receiving any new LSP from a given IS-IS router, the controller being 179 elected as DIS MUST flood it immediately to the management LAN for 180 two purposes: 1) implicitly acknowledging the receipt of that LSP; 2) 181 synchronizing that LSP to all the other IS-IS routers. 183 Futhermore, to decrease the frequency of advertising Complete 184 Sequence Number PDU (CSNP) on the controller being elected as DIS, 185 it's RECOMMENDED that IS-IS routers SHOULD send an explicit 186 acknowledgement with a Partial Sequence Number PDU (PSNP) upon 187 receiving a new LSP from the controller being elected as DIS. 189 4. Acknowledgements 191 TBD. 193 5. IANA Considerations 195 TBD. 197 6. Security Considerations 199 TBD. 201 7. References 203 7.1. Normative References 205 [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and 206 dual environments", RFC 1195, DOI 10.17487/RFC1195, 207 December 1990, . 209 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 210 Requirement Levels", BCP 14, RFC 2119, 211 DOI 10.17487/RFC2119, March 1997, 212 . 214 7.2. Informative References 216 [RFC4136] Pillay-Esnault, P., "OSPF Refresh and Flooding Reduction 217 in Stable Topologies", RFC 4136, DOI 10.17487/RFC4136, 218 July 2005, . 220 Author's Address 222 Xiaohu Xu 223 Huawei 225 Email: xuxiaohu@huawei.com