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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-17) exists of draft-ietf-ippm-ioam-data-00 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ippm H. Song, Ed. 3 Internet-Draft T. Zhou 4 Intended status: Standards Track Huawei 5 Expires: April 20, 2018 October 17, 2017 7 In-situ OAM Data Type Extension 8 draft-song-ippm-ioam-data-extension-00 10 Abstract 12 This document describes a proposal which extends in-situ OAM to 13 support potential future standard tracing data in addition to those 14 currently defined. We provide use cases to motivate our proposal and 15 base the modifications on the latest in-situ OAM header format 16 specification. 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 https://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 April 20, 2018. 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 (https://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. Motivation for Data Type Extension . . . . . . . . . . . . . 2 53 2. Scalable Data Type Extension . . . . . . . . . . . . . . . . 3 54 2.1. Data Type Bitmap . . . . . . . . . . . . . . . . . . . . 3 55 2.2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 4 56 2.3. Consideration for Efficient Data Packing . . . . . . . . 5 57 2.4. Alternative Data Extension Possibilities . . . . . . . . 5 58 3. Security Considerations . . . . . . . . . . . . . . . . . . . 6 59 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 60 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 61 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 62 7. Informative References . . . . . . . . . . . . . . . . . . . 6 63 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 65 1. Motivation for Data Type Extension 67 In-situ OAM (iOAM) [I-D.brockners-inband-oam-requirements] records 68 OAM information within user packets while the packets traverse a 69 network. The data types and data formats for in-situ OAM data 70 records have been defined in [I-D.ietf-ippm-ioam-data]. 72 Currently 12 data types and associated formats (including wide format 73 and short format of the same data) are defined in 74 [I-D.ietf-ippm-ioam-data] . The presence of data is indicated by a 75 16-bit bitmap in the "OAM-Trace-Type" field. 77 In the current specification only five bits are left to identify new 78 standard data types. Moreover, some data is forced to be bundled 79 together as a single unit to save bitmap space and pack data to the 80 ideal size (e.g., the hop limit and the node id are bundled, and the 81 ingress interface id and the egress interface id are bundled), 82 regardless of the fact that an application may only ask for a part of 83 the data. Last but not the least, each data is forced to be 4-byte 84 aligned for easier access, resulting in waste of header space in many 85 cases. 87 Since the data plane bandwidth, the data plane packet processing, and 88 the management plane data handling are all precious yet scarce 89 resource, the scheme should strive to be simple and precise. The 90 application should be able to control the exact type and format of 91 data it needs to collect and analyze. It is conceivable that more 92 types of data may be introduced in the future. However, the current 93 scheme cannot support it after all the bits in the bitmap are used 94 up. 96 For example, when a flow traverses a series of middleboxes (e.g., 97 Firewall, NAT, and load balancer), its identity (e.g., the 5-tuple) 98 is often altered, which makes the OAM system lose track of the flow 99 trace. In this case, we may want to copy some of the original packet 100 header fields into the iOAM header so the original flow can be 101 identified at any point of the network. 103 For another example, in wireless, mobile, and optical network 104 environments, some physical data associated with a flow (e.g., power, 105 temperature, signal strength, GPS location) need to be collected to 106 monitor the service performance. 108 Both cases require new iOAM data types. More examples are listed in 109 Section 2.2. 111 Currently, bit 7 is used to indicate the presence of variable length 112 opaque state snapshot data; Bit 5 and bit 10 are used to indicate the 113 presence of the application specific data. While these data fields 114 can be used to store arbitrary data, the data is difficult to be 115 standardized and another schema is needed to decode the data, which 116 may lead to low data plane performance as well as interoperability 117 issues. 119 2. Scalable Data Type Extension 121 Based on the observation in Section 1, we propose a method for data 122 type encoding which can solve the current limitation and address 123 future data requirements. 125 2.1. Data Type Bitmap 127 Bitmap is simple and efficient data structure for high performance 128 data plane implementation. The base bitmap size is kept to be 16 129 bits. We use one bit to indicate a single type of data in a single 130 format. The last bit in the bitmap (i.e., bit 15), if set, is used 131 to indicate the presence of the next data type bitmap, which is 32 132 bits long. In the second bitmap, bit 31 is again reserved to 133 indicate a third bitmap, and so on. With each extra bitmap, 31 more 134 data types can be defined. 136 Figure 1 shows an example of the in-situ OAM header format with two 137 extended OAM trace type fields. Except the OAM Trace Type fields, 138 all other fields remain the same as defined in 139 [I-D.ietf-ippm-ioam-data]. 141 0 1 2 3 142 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 1 143 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 | Base OAM Trace Type |1|NodeLen| Flags | Octets-left | 145 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 146 | Extended OAM Trace Type 1 |1| 147 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 148 | Extended OAM Trace Type 2 |0| 149 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 150 | | 151 | Node Data List [] | 152 | | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 155 Figure 1: Extended OAM Trace Type Header Format 157 The specification of the Base OAM Trace Type is the same as the OAM 158 Trace Type in [I-D.ietf-ippm-ioam-data] except the last bit, which is 159 defined as follows: 161 o Bit 15: When set indicates presence of next bit map. 163 The OAM trace type fields are labeled as Base OAM Trace Type, 164 Extended OAM Trace Type 1, Extended OAM Trace Type 2, and so on. The 165 Base OAM Trace Type is always present. If no data type is asked by 166 the application in Extended OAM Trace Type n and beyond, then the 167 last bit in the previous bitmap is set to 1 and these extended fields 168 are not included in the header. On the other hand, to eliminate 169 ambiguity, if any data is asked for by the application in Extended 170 OAM Trace Type n, then Extended OAM Trace Type 1 to (n-1) must be 171 included in the header, even though no data type in these bitmaps are 172 needed (i.e., all zero bitmap except the last bit). 174 The actual data in a node is packed together in the same order as 175 listed in the OAM Trace Type bitmap. Each node is padded to be the 176 multiple of 4 bytes. 178 2.2. Use Cases 180 New types of data can be potentially added and standardized, which 181 demand new bits allocated in the OAM Trace Type bitmaps. Some 182 examples are listed here. 184 o Metered flow bandwidth. 186 o Time gap between two consecutive flow packets. 188 o Remaining time budget to the packet delivery deadline. 190 o Buffer occupancy on the Node. 192 o Queue depth on each level of hierarchical QoS queues. 194 o Packet jitter at the Node. 196 o Current packet IP addresses. 198 o Current packet port numbers. 200 o Time using different network timing protocol. 202 o Other node statistics. 204 2.3. Consideration for Efficient Data Packing 206 The length of each data must be the multiple of 2 bytes. However, 207 allowing different data type to have different length, while 208 efficient in storage, makes data alignment and packing difficult. 210 If we can define the maximum number of data types that can be carried 211 per packet, the offset of each data in the node can be pre-calculated 212 and carried in the iOAM header. The overhead can be justified by the 213 overall space saving of the node data list. Otherwise, each data's 214 offset in the node must be calculated in each device, with the help 215 of a table which stores the size of each data type. We can also 216 arrange the bitmap to reflect the data availability order in the 217 system (e.g., the bit for egress_if_id must be after the bit for 218 ingress_if_id), so in a pipeline-based system, the required data can 219 be packed one after one. 221 2.4. Alternative Data Extension Possibilities 223 Bitmap is simple and support parallel processing in hardware. 224 However, it is not the only option to support data type extension. 225 For example, cascaded TLV can be used to support arbitrary number of 226 new data types. This can be implemented by using a flag bit to 227 indicate the presence of extra data types and packing the number of 228 types and the list of the type IDs after the trace option header. 229 The corresponding data is therefore added in each node data list in 230 the order as its type ID is listed in the extended trace option 231 header. 233 3. Security Considerations 235 There is no extra security considerations beyond those have been 236 identified by the original in-situ OAM proposals. 238 4. IANA Considerations 240 This memo includes no request to IANA. 242 5. Acknowledgments 244 We would like to thank Frank Brockners, Carlos Pignataro, and Shwetha 245 Bhandari for helpful comments and suggestions. 247 6. Contributors 249 The document is inspired by numerous discussions with James N. 250 Guichard. He also provided significant comments and suggestions to 251 help improve this document. 253 7. Informative References 255 [I-D.brockners-inband-oam-requirements] 256 Brockners, F., Bhandari, S., Dara, S., Pignataro, C., 257 Gredler, H., Leddy, J., Youell, S., Mozes, D., Mizrahi, 258 T., <>, P., and r. remy@barefootnetworks.com, 259 "Requirements for In-situ OAM", draft-brockners-inband- 260 oam-requirements-03 (work in progress), March 2017. 262 [I-D.ietf-ippm-ioam-data] 263 Brockners, F., Bhandari, S., Pignataro, C., Gredler, H., 264 Leddy, J., Youell, S., Mizrahi, T., Mozes, D., Lapukhov, 265 P., Chang, R., and d. daniel.bernier@bell.ca, "Data Fields 266 for In-situ OAM", draft-ietf-ippm-ioam-data-00 (work in 267 progress), September 2017. 269 Authors' Addresses 271 Haoyu Song (editor) 272 Huawei 273 2330 Central Expressway 274 Santa Clara, 95050 275 USA 277 Email: haoyu.song@huawei.com 278 Tianran Zhou 279 Huawei 280 156 Beiqing Road 281 Beijing, 100095 282 P.R. China 284 Email: zhoutianran@huawei.com