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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 date (April 04, 2011) is 4763 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Internet Engineering Task Force G. Karagiannis 2 Internet-Draft University of Twente 3 Intended status: Informational T. Taylor 4 Expires: October 04, 2011 K. Chan 5 Huawei Technologies 6 M. Menth 7 University of Tuebingen 8 P. Eardley 9 BT 10 April 04, 2011 12 Requirements for Signaling of (Pre-) Congestion Information in a 13 DiffServ Domain 14 draft-ietf-pcn-signaling-requirements-03 16 Abstract 18 Precongestion notification (PCN) is a means for protecting quality of 19 service for inelastic traffic admitted to a Diffserv domain. The 20 overall PCN architecture is described in RFC 5559. This memo 21 describes the requirements for the signaling applied within the PCN 22 domain: (1) PCN-feedback-information is carried from the PCN-egress- 23 node to the decision point;(2) the decision point may ask the PCN- 24 ingress-node to measure, and report back, the rate of PCN-traffic 25 between this pair of PCN-boundary-nodes. The decision point may be 26 either collocated with the PCN-ingress-node or a centralized node (in 27 the latter case, (2) is not required). The signaling requirements 28 pertain in particular to two edge behaviours, "controlled load (CL)" 29 and "single marking (SM)" [draft-ietf-pcn-cl-edge-behaviour-08], 30 [draft-ietf-pcn-sm-edge-behaviour-05]. 32 Status of this Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at http://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on September 02, 2011. 49 Copyright Notice 51 Copyright (c) 2010 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 Copyright (c) 2011 IETF Trust and the persons identified as the 55 document authors. All rights reserved. 57 This document is subject to BCP 78 and the IETF Trust's Legal 58 Provisions Relating to IETF Documents 59 (http://trustee.ietf.org/license-info) in effect on the date of 60 publication of this document. Please review these documents 61 carefully, as they describe your rights and restrictions with respect 62 to this document. Code Components extracted from this document must 63 include Simplified BSD License text as described in Section 4.e of 64 the Trust Legal Provisions and are provided without warranty as 65 described in the Simplified BSD License. 67 Requirements Language 69 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 70 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 71 document are to be interpreted as described in RFC 2119 [RFC2119]. 73 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 75 2. Signaling Requirements for Messages from the PCN-Egress-Nodes to 76 Decision Point(s) . . . . . . . . . . . . . . . . . . . . . . . . 3 77 2.1. Specification of Flow Identifiers . . . . . . . . . . . . . 4 78 3. Signaling Requirements for Messages between Decision Point(s) and 79 PCN-Ingress-Nodes . . . . . . . . . . . . . . . . . . . . . . . . 5 80 4. Security Considerations . . . . . . . . . . . . . . . . . . . . . 5 81 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . . 6 82 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6 83 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 84 7.1. Normative References . . . . . . . . . . . . . . . . . . . . 6 85 7.2. Informative References . . . . . . . . . . . . . . . . . . . 6 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 88 1. Introduction 90 The main objective of Pre-Congestion Notification (PCN) is to support 91 the quality of service (QoS) of inelastic flows within a Diffserv 92 domain in a simple, scalable, and robust fashion. Two mechanisms 93 are used: admission control and flow termination. Admission control 94 is used to decide whether to admit or block a new flow request while 95 flow termination is used in abnormal circumstances to decide 96 whether to terminate some of the existing flows. To support these 97 two features, the overall rate of PCN-traffic is metered on every 98 link in the domain, and PCN-packets are appropriately marked when 99 certain configured rates are exceeded. These configured rates are 100 below the rate of the link thus providing notification to boundary 101 nodes about overloads before any congestion occurs (hence "pre- 102 congestion" notification). The PCN-egress-nodes measure the rates of 103 differently marked PCN traffic in periodic intervals and report these 104 rates to the decision points for admission control and flow 105 termination, based on which they take their decisions. The decision 106 points may be collocated with the PCN-ingress-nodes or their function 107 may be implemented in a centralized node. 108 For more details see[RFC5559, [draft-ietf-pcn-cl-edge-behaviour-08], 109 [draft-ietf-pcn-sm-edge-behaviour-05]. 111 This memo specifies the requirements on signaling protocols: 112 o to carry reports from a PCN-egress-node to the decision point, 113 o to carry requests from the decision point to a PCN-ingress-node that 114 trigger the PCN-ingress-node to measure the PCN-sent-rate, 115 o to carry reports, from a PCN-ingress-node to the decision 116 point. 118 The latter two messages are only needed if the decision point and PCN- 119 ingress-node are not collocated. 121 2. Signaling Requirements for Messages from the PCN-Egress-Nodes to 122 Decision Point(s) 124 The PCN-egress-node measures, per ingress-egress-aggregate, the rates 125 of differently marked PCN-traffic in regular intervals. The 126 measurement intervals are recommended to take a fixed value between 127 100 ms and 500 ms, see [draft-ietf-pcn-cl-edge-behaviour-08], 128 [draft-ietf-pcn-sm-edge-behaviour-05]. At the end of each measurement 129 interval, the PCN-egress-node calculates the congestion-level-estimate 130 (CLE) based on these quantities. The PCN-egress-node MAY be configured 131 to record a set of identifiers of PCN-flows for which it received 132 excess-traffic-marked packets during the last measurement interval. 133 The latter may be useful to perform flow termination in networks with 134 multipath routing. 136 At the end of each measurement interval, or less frequently if 137 "optional report suppression" is activated, see 138 [draft-ietf-pcn-cl-edge-behaviour-08], [draft-ietf-pcn-sm-edge- 139 behaviour-05], the PCN-egress-node sends a report to the decision 140 point. 142 For the SM edge behaviour, the report MUST contain: 143 o the identifier of the PCN-ingress-node and the identifier of the 144 PCN-egress-node (typically their IP addresses); together they 145 specify the ingress-egress-aggregate to which the report refers, 146 o the rate of not-marked PCN-traffic (NM-rate) in octets/second, 147 o rate of PCN-marked traffic in octets/second, 148 o the congestion-level-estimate, which is a number between zero and 149 one. 151 For the CL edge behaviour, the report MUST contain: 152 o the identifier of the PCN-ingress-node and the identifier of the 153 PCN-egress-node (typically their IP addresses); together they 154 specify the ingress-egress-aggregate to which the report refers, 155 o the rate of threshold-marked PCN traffic (ThM-rate) in 156 octets/second, 157 o rate of excess-traffic-marked traffic (ETM-rate) in octets/second, 159 For both CL and SM edge behaviours, the report MAY also contain: 160 o a set of flow identifiers (see Section 2.1). 162 The signaling report can either be sent directly to the decision 163 point or it can "piggy-back", i.e. be included within some other 164 message that passes through the PCN-egress-node and then the decision 165 point. 167 Signaling messages SHOULD have a higher priority than data packets to 168 deliver them quickly and to avoid that they are dropped in case of 169 overload. 171 The load generated by the signaling protocol SHOULD be minimized. We 172 give three examples that may help to achieve that goal: 173 o Piggy-backing the reports by the PCN-egress-nodes to the decision 174 point(s) onto other signaling messages that are already in place. 175 o Reducing the amount of reports to be sent by optional report 176 suppression. 177 o combining reports for different ingress-egress-aggregates in a 178 single message (if they are for the same decision point). 180 As PCN reports are sent regularly, additional reliability mechanisms 181 are not needed. This also holds in the presence of optional report 182 suppression, as reports are sent periodically if actions by the 183 decision point(s) are needed, see [draft-ietf-pcn-cl-edge-behaviour- 184 -08], [draft-ietf-pcn-sm-edge-behaviour-05]. 186 2.1 Specification of Flow Identifiers 188 The representation of a flow identifier depends on the surrounding 189 environment, e.g., pure IP, MPLS, GMPLS, etc. Examples of such flow 190 identifier representations can be found in [RFC2205], [RFC3175] 191 [RFC3209], [RFC3473], [RFC4804]. 193 In pure IP networks, the identifier may consist of a subset of the 194 following information: 196 o source IP address; 197 o destination IP address; 199 o protocol identifier and higher layer (port) addressing; 201 o flow label (typical for IPv6); 203 o SPI field for IPsec encapsulated data; 205 o DSCP/TOS field; 207 o IP address of PCN-ingress-node; 209 o IP address of PCN-egress-node 211 3. Signaling Requirements for Messages between Decision Point(s) and 212 PCN-Ingress-Nodes 214 Through request-response signaling between the decision point and PCN- 215 ingress-node, the decision point requests and in response the PCN- 216 ingress-node measures and reports the PCN-sent-rate for a specific 217 ingress-egress-aggregate. Signaling is needed only if the decision 218 point and PCN-ingress-node are not collocated. 220 The request MUST contain: 221 o an indication that the PCN-sent-rate is requested, 222 o the identifier of the PCN-ingress-node and the identifier of the 223 PCN-egress-node; together they determine the ingress-egress- 224 aggregate for which the PCN-sent-rate is requested, 225 o the identifier of the decision point that requests the PCN-sent- 226 rate. 228 The report MUST contain: 229 o an indication that the reported data is a PCN-sent-rate, 230 o the PCN-sent-rate in octets/second, 231 o the identifier of the PCN-ingress-node and the identifier of the 232 PCN-egress-node. 234 The request MUST be addressed to the PCN-ingress-node, and the report 235 MUST be addressed to the decision point that requested it. 237 The request and the report SHOULD be sent with high priority and 238 reliably, because they are sent only when flow termination is needed, 239 which is an urgent action. 241 4. Security Considerations 243 [RFC5559] provides a general description of the security 244 considerations for PCN. This memo does not introduce additional 245 security considerations. 247 5. IANA Considerations 249 This memo includes no request to IANA. 251 6. Acknowledgements 253 We would like to acknowledge the members of the PCN working group for 254 the discussions that generated the contents of this memo. 256 7. References 258 7.1. Normative References 260 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 261 Requirement Levels", BCP 14, RFC 2119, March 1997. 263 [RFC5559] Eardley, P., "Pre-Congestion Notification (PCN) 264 Architecture", RFC 5559, June 2009. 266 [draft-ietf-pcn-cl-edge-behaviour-08] T. Taylor, A, Charny, 267 F. Huang, G. Karagiannis, M. Menth, "PCN Boundary Node 268 Behaviour for the Controlled Load (CL) Mode of Operation 269 (Work in progress)", December 2010. 271 [draft-ietf-pcn-sm-edge-behaviour-05] A. Charny, J. Zhang, 272 G. Karagiannis, M. Menth, T. Taylor, "PCN Boundary Node 273 Behaviour for the Single Marking (SM) Mode of Operation 274 (Work in progress)", December 2010. 276 7.2. Informative References 278 [RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S. 279 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 280 Functional Specification", RFC 2205, September 1997. 281 [RFC3175] Baker, F., Iturralde, C. Le Faucher, F., Davie, B., 282 "Aggregation of RSVP for IPv4 and IPv6 Reservations", 283 RFC 3175, 2001. 285 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 286 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 287 Tunnels", RFC 3209, December 2001. 289 [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching 290 (GMPLS) Signaling Resource ReserVation Protocol-Traffic 291 Engineering (RSVP-TE) Extensions", RFC 3473, 292 January 2003. 294 [RFC4804] F. Le Faucheur, "Aggregation of Resource ReSerVation 295 Protocol (RSVP) Reservations over MPLS TE/DS-TE Tunnels", 296 RFC 4804, February 2007. 298 Authors' Addresses 300 Georgios Karagiannis 301 University of Twente 302 P.O. Box 217 303 7500 AE Enschede, 304 The Netherlands 305 EMail: g.karagiannis@ewi.utwente.nl 307 Tom Taylor 308 Huawei Technologies 309 1852 Lorraine Ave. 310 Ottawa, Ontario K1H 6Z8 311 Canada 312 Phone: +1 613 680 2675 313 Email: tom111.taylor@bell.net 315 Kwok Ho Chan 316 Huawei Technologies 317 125 Nagog Park 318 Acton, MA 01720 319 USA 320 Email: khchan@huawei.com 322 Michael Menth 323 University of Tuebingen 324 Department of Computer Science 325 Chair of Communication Networks 326 Sand 13 327 Tuebingen 72076 328 Germany 329 Phone: +49 7071 29 70505 330 Email: menth@informatik.uni-tuebingen.de 332 Philip Eardley 333 BT 334 B54/77, Sirius House Adastral Park Martlesham Heath 335 Ipswich, Suffolk IP5 3RE 336 United Kingdom 337 EMail: philip.eardley@bt.com