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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to lack the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords -- however, there's a paragraph with a matching beginning. Boilerplate error? (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). == 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: when value is set to 0 then last 4 bytes of this TLV MUST not be present in the packet, Auth Len MUST be set to 8 bytes. When set to 1 Auth Len MUST be set to 12. -- The document date (June 10, 2015) is 3240 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) == Unused Reference: 'RFC2119' is defined on line 262, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Routing Working Group A. Mishra 3 Internet-Draft M. Jethanandani 4 Intended status: Standards Track A. Saxena 5 Expires: December 12, 2015 Ciena Corporation 6 S. Pallagatti 7 Juniper Networks 8 M. Chen 9 Huawei 10 P. Fan 11 China Mobile 12 June 10, 2015 14 BFD Stability 15 draft-ashesh-bfd-stability-03.txt 17 Abstract 19 This document describes extensions to the Bidirectional Forwarding 20 Detection (BFD) protocol to measure BFD stability. Specifically, it 21 describes a mechanism for detection of BFD frame loss. 23 Requirements Language 25 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 26 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 27 document are to be interpreted as described in RFC 2119. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on December 12, 2015. 47 Copyright Notice 49 Copyright (c) 2015 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3 66 3. BFD Null-Authentication TLV . . . . . . . . . . . . . . . . . 3 67 4. Theory of Operations . . . . . . . . . . . . . . . . . . . . 4 68 4.1. Loss Measurement . . . . . . . . . . . . . . . . . . . . 4 69 4.2. Delay Measurement . . . . . . . . . . . . . . . . . . . . 5 70 5. IANA Requirements . . . . . . . . . . . . . . . . . . . . . . 5 71 6. Security Consideration . . . . . . . . . . . . . . . . . . . 6 72 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 73 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 74 9. Normative References . . . . . . . . . . . . . . . . . . . . 6 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 77 1. Introduction 79 The Bidirectional Forwarding Detection (BFD) protocol operates by 80 transmitting and receiving control frames, generally at high 81 frequency, over the datapath being monitored. In order to prevent 82 significant data loss due to a datapath failure, the tolerance for 83 lost or delayed frames (the Detection Time as described in RFC 5880) 84 is set to the smallest feasible value. 86 This document proposes a mechanism to detect delayed or lost frames 87 in a BFD session in addition to the datapath fault detection 88 mechanisms of BFD. Such a mechanism presents significant value with 89 the ability to measure the stability of BFD sessions and provides 90 data to the operators. 92 This document does not propose BFD extension to measure data traffic 93 loss or delay on a link or tunnel and the scope is limited to BFD 94 frames. 96 2. Use cases 98 Legacy BFD can't detect any BFD frame delay or loss if delay or loss 99 does not last for dead interval. Frequent delay or loss of BFD 100 frames could potentially lead to flap. 102 It may be possible that network has healthy link or tunnel but only 103 BFD frames are getting dropped or delayed. This potentially leads to 104 network convergence or use of suboptimal path when fast reroute is 105 enabled such as: 107 Routing protocols with LFA enabled, BFD is used to monitor the 108 link. 110 Aggregate Ethernet with BFD to monitor each member link. 112 Primary and protected tunnels with BFD to monitor tunnels. 114 This proposal will help BFD session to give more information to 115 operator about the health of BFD session that could be used to avoid 116 BFD session flap with faulty BFD path on a healthy link or tunnel. 118 In a faulty link or tunnel scenario operator can use BFD health 119 information to dynamically run delay and loss measurement OAM 120 protocol (CFM or LM-DM) to further isolate the issue. 122 3. BFD Null-Authentication TLV 124 The functionality proposed for BFD stability measurement is achieved 125 by appending the Null-Authentication TLV to the BFD control frame. 127 The Null-Authentication TLV (called 0-Auth in this document) extends 128 the existing BFD Authentication TLV structure by adding a new Auth- 129 Type of . This TLV carries the Sequence Number for 130 frame loss measurement and optional sender timestmap. 132 0 1 2 3 133 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | Auth Type | Auth Len | Auth Key ID | Reserved | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 | Sequence Number | 138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 | Sender timestmap | 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 142 where: 144 Auth Type: The Authentication Type, which in this case is (Null Authentication). 147 Auth Len: The length of the Authentication Section, in bytes. Length 148 depends on the Auth Key ID. 150 Auth Key ID: The Authentication Key ID is used to control optional 151 feature. Vales are: 153 0 -- BFD loss measurement 154 1 -- BFD loss and delay measurement 155 2-255 -- Reserved for future use 157 when value is set to 0 then last 4 bytes of this TLV MUST not be 158 present in the packet, Auth Len MUST be set to 8 bytes. When set to 159 1 Auth Len MUST be set to 12. 161 Sequence Number: This indicates the sequence number for this packet 162 and MUST be present in every 0-Auth TLV. This value is incremented 163 by 1 for every frame transmitted while the session state is UP. A 164 value of 0 indicates a request by sender to reset the sequence number 165 correlation logic at the receiver. The first frame transmitted by 166 the sender MAY set this field to 0. 168 Sender timestamp: MUST be set to time when packet is about to leave 169 the sender system. Sender system MAY time stamp this as close to 170 wire when packet is about to leave system. Details of how sender 171 system timestamps is out of the scope of this document. 173 4. Theory of Operations 175 This mechanism allows operator to measure the loss and delay of BFD 176 CC frames. 178 4.1. Loss Measurement 180 This measurement counts the number of BFD control frames missed at 181 the receiver due to a transient change in the network such as 182 congestion. Frame-loss is detected by comparing the Sequence Number 183 field in the 0-Auth TLV in successive BFD CC frames. The Sequence 184 Number in each successive control frame generated on a BFD session by 185 the transmitter is incremented by one. 187 The first BFD 0-Auth TLV processed by the receiver that has a non- 188 zero sequence number is used for bootstrapping the logic. Each 189 successive frame after this is expected to have a Sequence Number 190 that is one greater than the Sequence Number in the previous frame. 192 BFD being aggressive protocol, sequence number may wrap to 0 within 193 few hundred days. Sender MUST ensure that when sequence number is 194 wrapped, it starts with value 1. Receiver MUST accept this BFD 195 packet and adjust his next anticipated sequence number. 197 4.2. Delay Measurement 199 Delay measurement can be done in two ways. 201 Using sender timestamp in 0-Auth TLV: 203 If AuthKey ID in 0-Auth TLV is set to 1 then sender timestamp 204 MUST be set. Delay measurement is the difference between the 205 sender timestamp on any two consecutive BFD CC frames that 206 carry the 0-Auth TLV with AuthKey ID set to 1 for a session. 207 This is a key metric to determine transient changes in 208 stability of BFD transmission engine or to determine the 209 systems capability of handling the existing load. A 210 significant deviation from the negotiated transmission interval 211 on the local node indicates potential instabilities in the BFD 212 transmission engine. Based on the timestamp measurements, the 213 operator MAY take action to configure the system to maintain 214 normal operation of the node. 216 Similar delay measurements on the receiver can be made using 217 timestamps in the meta data when packet is received. In 218 conjunction with sender delay measurements, these can indicate 219 delays caused by data-path. While a constant delay may not be 220 indicator of instability, large transient delays can decrease 221 the BFD session stability significantly. 223 Using centralized controller: 225 When AuthKey ID in 0-Auth TLV is set to 0 then sender timestmap 226 will not be present in the packet. Peers MAY still choose to 227 do delay measurement by sending their packet sent timestamps to 228 central control unit. Central control unit MAY gather all 229 timestamp information and can do delay calculation for a BFD 230 session. Details of how BFD component sends timestamps to 231 central unit is outside the scope of this document. 233 5. IANA Requirements 235 IANA is requested to assign new Auth-Type for the Null-Authentication 236 TLV for BFD Stability Measurement. The following number is 237 suggested. 239 Value Meaning 240 6 Null-Authentication TLV 242 6. Security Consideration 244 Other than concerns raised in [RFC5880] there are no new concerns 245 with this proposal. 247 7. Contributors 249 Manav Bhatia 250 manav@ionosnetworks.com 251 Ionos Networks 252 Bangalore, India 254 8. Acknowledgements 256 Authors would like to thank Nobo Akiya, Jeffery Haas, Peng Fan, 257 Dileep Singh, Basil Saji, Sagar Soni and Mallik Mudigonda who also 258 contributed to this document. 260 9. Normative References 262 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 263 Requirement Levels", BCP 14, RFC 2119, March 1997. 265 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 266 (BFD)", RFC 5880, June 2010. 268 Authors' Addresses 270 Ashesh Mishra 271 Ciena Corporation 272 3939 North 1st Street 273 San Jose, CA 95134 274 USA 276 Email: mishra.ashesh@gmail.com 277 URI: www.ciena.com 279 Mahesh Jethanandani 280 Ciena Corporation 281 3939 North 1st Street 282 San Jose, CA 95134 283 USA 285 Email: mjethanandani@gmail.com 286 URI: www.ciena.com 287 Ankur Saxena 288 Ciena Corporation 289 3939 North 1st Street 290 San Jose, CA 95134 291 USA 293 Email: ankurpsaxena@gmail.com 295 Santosh Pallagatti 296 Juniper Networks 297 Juniper Networks, Exora Business Park 298 Bangalore, Karnataka 560103 299 India 301 Phone: + 302 Email: santoshpk@juniper.net 304 Mach Chen 305 Huawei 307 Email: mach.chen@huawei.com 309 Peng Fan 310 China Mobile 311 32 Xuanwumen West Street 312 Beijing, Beijing 313 China 315 Email: fanp08@gmail.com