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'5' on line 637 looks like a reference -- Missing reference section? '9' on line 649 looks like a reference Summary: 9 errors (**), 0 flaws (~~), 4 warnings (==), 11 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Real Time Flow Measurement Working Group S.W. Handelman 3 Internet-draft IBM 4 Hawthorne, NY USA 6 Nevil Brownlee 7 U of Auckland, NZ 9 Greg Ruth 10 GTE Laboratories, Inc 11 Waltham, MA USA 13 S. Stibler 14 IBM 15 Hawthorne, NY USA 17 September 29, 1998 18 expires 19 March 1, 1999 21 RTFM Working Group - New Attributes for Traffic Flow Measurement 23 25 1. Status of this Memo 27 This document is an Internet-Draft. Internet-Drafts are working 28 documents of the Internet Engineering Task Force (IETF), its areas, 29 and its working groups. Note that other groups may also distribute 30 working documents as Internet-Drafts. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet- Drafts as reference 35 material or to cite them other than as "work in progress." 37 To view the entire list of current Internet-Drafts, please check the 38 "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow 39 Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern 40 Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific 41 Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). 43 2. Introduction 45 The Real-Time Flow Measurement (RTFM) Working Group (WG) has 46 developed a system for measuring and reporting information about 47 traffic flows in the Internet. This document explores the definition 48 of extensions to the flow measurements as currently defined in [1]. 49 The new attributes described in this document will be useful for 50 monitoring network performance and will expand the scope of RTFM 51 beyond simple measurement of traffic volumes. A companion document 52 to this draft will be written to define MIB structures for the new 53 attributes. 55 This draft was started in 1996 to advance the work of the RTFM group. 56 The goal of this work is to produce a simple set of abstractions, 57 which can be easily implemented and at the same time enhance the 58 value of RTFM Meters. This document also defines a method for 59 organising the flow abstractions to augment the existing RTFM flow 60 table. 62 Implementations of the RTFM Meter have been done by Nevil Brownlee in 63 the University of Auckland, NZ, and Stephen Stibler and Sig Handelman 64 at IBM in Hawthorne, NY, USA. The RTFM WG has also defined the role 65 of the Meter Reader whose role is to retrieve flow data from the 66 Meter. 68 Note on flows and positioning of meters. 70 A flow as it traverses the Internet, may have some of its 71 characteristics altered as it travels through Routers, Switches, and 72 other network units. It is important to note the spatial location of 73 the Meter when referring to attributes of a flow. An example, a 74 server may send a sequence of packets with a definite order, and 75 inter-packet timing with a leaky bucket algorithm. A meter reading 76 downstream of the leaky bucket would record a set with minimal inter 77 packet timing due to the leaky bucket. At the client's location, the 78 packets may arrive out of sequence, with the timings altered. A meter 79 at the client's location would record different attributes for the 80 same flow. 82 2.1 RTFM's Definition of Flows 84 The RTFM Meter architecture views a flow as a set of packets between 85 two endpoints (as defined by their source and destination attribute 86 values and start and end times), and as BI-DIRECTIONAL (i.e. the 87 meter effectively monitors two sub-flows, one in each direction). 89 Reasons why RTFM flows are bi-directional: 91 - The WG is interested in understanding the behaviour of sessions 92 between endpoints. 94 - The endpoint attribute values (the "Address" and "Type" ones) are 95 the same for both directions; storing them in bi-directional flows 96 reduces the meter's memory demands. 98 - 'One-way' (uni-directional) flows are a degenerate case. Existing 99 RTFM meters can handle this by using one of the computed attributes 100 e.g. FlowKind) to indicate direction. 102 2.2 RTFM's Current Definition of Flows and their Attributes 104 Flows, as described in the "Architecture" document [1] have the 105 following properties: 107 a. They occur between two endpoints, specified as sets of attribute 108 values in the meter's current rule set. A flow is completely 109 identified by its set of endpoint attribute values. 111 b. Each flow may also have values for "computed" attributes (Class 112 and Kind). These are directly derived from the endpoint attribute 113 values. 115 c. A new flow is created when a packet is to be counted that does not 116 match the attributes of an existing flow. The meter records the time 117 when this new flow is created. 119 d. Attribute values in (a), (b) and (c) described above are set when 120 the meter sees the first packet for the flow, and are never changed. 122 e. Each flow has a "LastTime" attribute, which indicates the time the 123 meter last saw a packet for the flow. 125 f. Each flow has two packet and two byte counters, one for each flow 126 direction (Forward and Backward). These are updated as packets for 127 the flow are observed by the meter. 129 g. ALL the attributes have (more or less) the same meaning for a 130 variety of protocols; IPX, AppleTalk, DECnet and CLNS as well as 131 TCP/IP. 133 Current flow attributes - as described above - fit very well into the 134 SNMP data model. They are either static, or are continuously updated 135 counters. They are NEVER reset. In this document they will be 136 referred to as "old-style" attributes. 138 It is easy to add further "old-style" attributes, since they don't 139 require any new features in the architecture. For example: 141 - Count of the number of "lost" packets (inferred by watching 142 sequence number fields for packets in each direction; only available 143 for protocols which have such sequence numbers). 145 - In the future, RTFM could coordinate directly with the Flow Label 146 from the IPv6 header. 148 2.3 RTFM Flows, Integrated Services, IPPM and Research in Flows 150 The concept of flows has been studied in various different contexts. 151 For the purpose of extending RTFM, a starting point is the work of 152 the Integrated Services WG. We will measure quantities that are often 153 set by Integrated Services configuration programs. We will look at 154 the work of the Benchmarking / IP Performance Metrics Working Group, 155 and also look at the work of Claffy, Braun and Polyzos [4]. We will 156 demonstrate how RTFM can compute throughput, packet loss, and delays 157 from flows. 159 An example of the use of capacity and performance information is 160 found in "The Use of RSVP with IETF Integrated Services" [2]. RSVP's 161 use of Integrated Services revolves around Token Bucket Rate, Token 162 Bucket Size, Peak Data Rate, Minimum Policed Unit, Maximum Packet 163 Size, and the Slack term. These are set by TSpec, ADspec and FLowspec 164 (Integrated Services Keywords), and are used in configuration and 165 operation of Integrated Services. RTFM could monitor explicitly Peak 166 Data Rate, Minimum Policed Unit, Maximum Packet Size, and the Slack 167 term. RTFM could infer details of the Token Bucket. The WG will 168 develop measures to work with these service metrics. An initial 169 implementation of IIS Monitoring has been developed at CEFRIEL in 170 Italy [8]. 172 RTFM will work with several traffic measurements identified by IPPM 173 [3]. There are three broad areas in which RTFM is useful for IPPM. 174 An RTFM Meter could act as a passive device, gathering traffic and 175 performance statistics at appropriate places in networks (server or 176 client locations). RTFM could give detailed analyses of IPPM test 177 flows that pass through the Network segment that RTFM is monitoring. 178 RTFM could be used to identify the most-used paths in a network mesh, 179 so that detailed IPPM work could be applied to these most used paths. 181 3.0 Flow Abstractions 183 Performance attributes include throughput, packet loss, delays, 184 jitter, and congestion measures. RTFM will calculate these attributes 185 in the form of extensions to the RTFM flow attributes according to 186 three general classes: 188 - 'trace' attributes of individual packets in a flow or a segment of 189 a flow (e.g. last packet size, last packet arrival time). 191 - 'aggregates' statistics derived from the flow taken as a whole 192 (e.g. mean rates, max packet size, packet size distribution). 194 - 'group' attributes that depend on groups of packet values within 195 the flow (e.g. inter-arrival times, short-term traffic rates). 197 Note that attributes within each of these classes may have various 198 types of values - numbers, distributions, time series, and so on. 200 3.1 Meter Readers and Meters 202 A note on the relation between Meter Readers and Meters. 204 Several of the measurements enumerated below can be implemented by a 205 Meter Reader that is tied to the meter with very short response time 206 and very high bandwidth. If the Meter Reader and Meter can be 207 arranged in such a way, RTFM could collect Packet Traces with time 208 stamps and provide them directly to the Meter Reader for further 209 processing. 211 A more useful alternative is to have the Meter calculate some flow 212 statistics locally. This allows a looser coupling between the Meter 213 and Meter Reader. RTFM will monitor an 'extended attribute' depending 214 upon settings in its Rule table. RTFM will not create any "extended 215 attribute" data without explicit instructions in the Rule table. 217 3.2. Attribute Types 219 Section 3.0 described three different classes of attributes; this 220 section considers the "data types" of these attributes. 222 Packet Traces (as described below) are a special case in that they 223 are tables with each row containing a sequence of values, each of 224 varying type. They are essentially 'compound objects' i.e. lists of 225 attribute values for a string of packets. 227 Aggregate attributes are like the 'old-style' attributes. The types 228 are 230 - Addresses, represented as byte strings (1 to 20 bytes long) 231 - Counters, represented as 64-bit unsigned integers 233 - Times, represented as 32-bit unsigned integers 235 Addresses are saved when the first packet of a flow is observed. They 236 do not change with time, and they are used as a key to find the 237 flow's entry in the meter's flow table. 239 Counters are incremented for each packet, and are never reset. An 240 analysis application can compute differences between readings of the 241 counters, so as to determine rates for these attributes. For 242 example, if we read flow data at five-minute intervals, we can 243 calculate five-minute packet and byte rates for the flow's two 244 directions. 246 Times - the FirstTime for a flow is set when its first packet is 247 observed. LastTime is updated as each packet in the flow is observed. 249 All the above types have the common feature that they are expressed 250 as single values. At least some of the new attributes will require 251 multiple values. If, for example, we are interested in inter-packet 252 time intervals, we can compute an interval for every packet after 253 the first. If we are interested in packet sizes, a new value is 254 obtained as each packet arrives. When it comes to storing this data 255 we have two options: 257 - As a sequence of single values. This saves all the information, 258 but does not fit well with the RTFM goal of doing as much data 259 reduction as possible within the meter. 261 - As a distribution, i.e. in an array of 'buckets.' This method is 262 a compact representation of the data, with the values being stored as 263 counters between a minimum and maximum, with defined steps in each 264 bucket. This fits the RTFM goal of compact data storage. 266 Studies which would be limited by the use of distributions might well 267 use packet traces instead. 269 A method for specifying the distribution parameters, and for encoding 270 the distribution so that it can be easily read, is described in 271 section 4.2. 273 3.3 Packet Traces 275 The simplest way of collecting a trace in the meter would be to have 276 a new attribute called, say, "PacketTrace." Data could be stored in 277 a table, with a column for each property of interest. For example, 278 one could trace: 280 - Packet Arrival time (TimeTicks from sysUpTime, or microseconds from 281 FirstTime for the flow). 283 - Packet Direction (Forward or Backward) 285 - Packet Sequence number (for protocols with sequence numbers) 287 - Packet Flags (for TCP at least) 289 Note: The following implementation proposal is for the user who is 290 familiar with the writing of rule sets for the RTFM Meter. 292 To add a row to the table, we only need a rule which PushPkts the 293 PacketTrace attribute. To use this, one would write a rule set which 294 selected out a small number of flows of interest, with a 'PushPkt 295 PacketTrace' rule for each of them. A MaxTraceRows default value of 296 2000 would be enough to allow a Meter Reader to read one-second ping 297 traces every 10 minutes or so. More realistically, a MaxTraceRows of 298 500 would be enough for one-minute pings, read once each hour. Note 299 that packet traces are already implemented in the RMON MIB [6], in 300 the Packet Capture Group. They are therefore a low priority for RTFM. 302 3.4 Aggregate Attributes 304 RTFM's "old-style" flow attributes count the bytes and packets for 305 those packets which match the rule set for an individual flow. In 306 addition to these totals, RTFM could calculate Packet Size 307 statistics. This data can be stored as distributions, though it may 308 sometimes be sufficient to simply keep a single e.g. maximum value. 310 Packet Size - RTFM's packet flows can be examined to determine the 311 maximum packet size found in a flow. This will give the Network 312 Operator an indication of the MTU being used in a flow. It will also 313 give an indication of the sensitivity to loss of a flow, as losing 314 large packets causes more data to be retransmitted. 316 Note that aggregate attributes are a simple extension of the 'old- 317 style' attributes; their values are never reset. For example, an 318 array of counters could hold a 'packet size' distribution. The 319 counters continue to increase, a meter reader will collect their 320 values at regular intervals, an analysis application will compute and 321 display distributions of the packet size for each collection 322 interval. 324 If we are interested in '10-second' forward data rates, the meter 325 might compute this for each flow of interest as follows: 327 - maintain an array of counters to hold the flow's 10-second data 328 rate distribution. 330 - every 10 seconds, compute and save 10-second octet rate. 332 To achieve this, the meter will have to keep a list of aggregate 333 flows and the intervals at which they require processing. Careful 334 programming is needed to achieve this, but provided the meter is not 335 asked to do it for very large numbers of flows, it has been 336 successfully implemented. 338 3.5 Group Attributes 340 The notion of group attributes is to keep simple statistics for 341 measures that involve more than one packet. This section describes 342 some group attributes which are feasible to implement in a traffic 343 meter, and which seem interesting and useful. 345 Short-term bit rate. (This data could also be recorded as the maximum 346 and minimum data rate of the flow, found over specific time periods 347 during the lifetime of a flow; this is a special kind of 348 'distribution'.) Bit rate could be used to define the throughput of a 349 flow, and if the RTFM flow is defined to be the sum of all traffic in 350 a network, one can find the throughput of the network. 352 Inter-arrival times. The Meter knows the time that it encounters each 353 individual packet. Statistics can be kept to record the inter-arrival 354 times of the packets, which would give an indication of the jitter 355 found in the Flow. 357 Turn-around statistics. Sine the Meter knows the time that it 358 encounters each individual packet, it can produce statistics of the 359 time intervals between packets of a flow observed travelling in 360 positive directions on the network. For protocols such as SNMP 361 (where every packet request packet elicits an answering packet) this 362 gives a good indication of turn-around times. 364 Subflow analysis. Since the choice of flow endpoints is controlled 365 by the meter's rule set, it is easy to define an aggregate flow, e.g 366 "all the TCP streams between hosts A and B." Preliminary 367 implementation work suggests that - at least for this case - it 368 should be possible for the meter to maintain a table of information 369 about all the active streams. This could be used to produce at least 370 the following attributes: 371 - Number of streams, e.g. streams active for n-second intervals. 373 Determined for TCP and UDP using source-dest port number pairs. 374 - Number of TCP bytes, determined by taking difference of TCP 375 sequence numbers for each direction of the aggregate flow. 377 IIS attributes. Work at CEFRIEL [8] has produced a traffic meter 378 with a rule set modified 'on the fly' so as to maintain a list of 379 RSVP-reserved flows. For such flows the following attributes have 380 been implemented: 382 - QoSService: Service class for the flow 383 (guaranteed, controlled load) 384 - QoSStyle: Reservation setup style (wildcard 385 filter,fixed filter,shared explicit) 386 - QoSRate: [byte/s] rate for flows with guaranteed 387 service 388 - QoSSlackTerm: [microseconds] Slack Term QoS parameter for 389 flows with guaranteed service 390 - QoSTokenBucketRate: [byte/s] Token Bucket Rate QoS parameter 391 for flows with guaranteed service 393 3.6 Actions on Exceptions 395 Some users of RTFM have requested the ability to mark flows as having 396 High Watermarks. The existence of abnormal service conditions, such 397 as non-ending flow, a flow that exceeds a given limit in traffic 398 (e.g. a flow that is exhausting the capacity of the line that carries 399 it) would cause an ALERT to be sent to the Meter Reader for 400 forwarding to the Manager. Operations Support could define service 401 situations in many different environments. This is an area for 402 further discussion on Alert and Trap handling. 404 4. Extensions to the 'Basic' RTFM Meter 406 The WG has agreed that the basic RTFM Meter will not be altered by 407 the addition of the new attributes of this document. This section 408 describes the extensions needed to implement the new attributes. 410 4.1 Flow table extensions 412 The architecture of RTFM has defined the structure of flows, and this 413 draft does not change that structure. The flow table could have 414 ancillary tables called "Distribution Tables" and "Trace Tables," 415 these would contain rows of values and or actions as defined above. 416 Each entry in these tables would be marked with the number of its 417 corresponding flow in the RTFM flow table. 419 Note: The following section is for the user who is familiar with the 420 writing of rule sets for the RTFM Meter. 422 In order to identify the data in a Packet Flow Table, the attribute 423 name could be pushed into a string at the head of each row. For 424 example, if a table entry has "To Bit Rate" for a particular flow, 425 the "ToBitRate" string would be found at the head of the row. (An 426 alternative method would be to code an identification value for each 427 extended attribute and push that value into the head of the row.) See 428 section 5.0 for an initial set of ten extended flow attributes. 430 4.2. Specifying Distributions in RuleSets 432 At first sight it would seem necessary to add extra features to the 433 RTFM Meter architecture to support distributions. This, however, is 434 not necessarily the case. 436 What is actually needed is a way to specify, in a ruleset, the 437 distribution parameters. These include the number of counters, the 438 lower and upper bounds of the distribution, whether it is linear or 439 logarithmic, and any other details (e.g. the time interval for 440 short-term rate attributes). 442 Any attribute which is distribution-valued needs to be allocated a 443 RuleAttributeNumber value. These will be chosen so as to extend the 444 list already in the RTFM Meter MIB document [7]. 446 Since distribution attributes are multi-valued it does not make sense 447 to test them. This means that a PushPkt (or PushPkttoAct) action 448 must be executed to add a new value to the distribution. The old- 449 style attributes use the 'mask' field to specify which bits of the 450 value are required, but again, this is not the case for 451 distributions. Lastly, the MatchedValue ('value') field of a PushPkt 452 rule is never used. Overall, therefore, the 'mask' and 'value' 453 fields in the PushPkt rule are available to specify distribution 454 parameters. 456 Both these fields are at least six bytes long, the size of a MAC 457 address. All we have to do is specify how these bytes should be 458 used! As a starting point, the following is proposed (bytes are 459 numbered left-to-right. 461 Mask bytes: 462 1 Transform 1 = linear, 2 = logarithmic 463 2 Scale Factor Power of 10 multiplier for Limits and Counts 464 3-4 Lower Limit Highest value for first bucket 465 5-6 Upper Limit Highest value for last bucket 467 Value bytes: 468 1-2 Buckets Number of buckets. Does not include 469 the 'overflow' bucket 471 3-4 Parameter-1 Parameter use depends on 472 5-6 Parameter-2 distribution attribute 474 For example: 476 ToPacketSize & 1.0,15,1500 = ,100,0,0: PushPkt, Next 478 FromBitrate & 2.3,16,2048 = ,7,5,0: PushPkt, Next 480 In these mask and value fields a dot indicates that the preceding 481 number is a one-byte integer, the commas indicate that the preceding 482 number is a two-byte integer, and the last number is two bytes wide 483 since this was the width of the preceding field. (Note that this 484 convention follows that for IP addresses - 130.216 means 130.216.0.0) 486 The first rule specifies that a distribution of packet sizes is 487 to be built. It uses an array of 100 buckets, storing values 488 from 1 to 1500 bytes (i.e. linear steps of 15 bytes each). Any 489 packets with size greater than 1500 will be counted in the 'overflow' 490 bucket, hence there are 101 counters for the distribution. 492 The second rule specifies a bit-rate distribution, with the rate 493 being calculated every 5 seconds (parameter 1). A logarithmic 494 array of 7 counters (and an overflow bucket) are used for 495 rates from 16,000 bps to 2,048,000 bps. The scale factor of 3 indicates 496 that the limits are given in thousands of bits per second. 498 These distribution parameters will need to be stored in the meter 499 so that they are available for building the distribution. They 500 will also need to be read from the meter and saved together with 501 the other flow data. 503 4.3 Reading Distributions 505 Since RTFM flows are bi-directional, each distribution-valued quantity 506 (e.g. packet size, bit rate, etc.) 507 will actually need two sets of counters, one for packets travelling in each direction. 508 It is 509 tempting to regard these as components of a single 'distribution,' but 510 in many cases only one of the two directions will be of interest; it 511 seems better to keep them in separate distributions. This is similar 512 to the old-style counter-valued attributes such as toOctets and fromOctets. 514 A distribution should be read by a meter reader as a single, 515 structured object. The components of a distribution object are 517 - 'mask' and 'value' fields from the rule which created the distribution 518 - sequence of counters ('buckets' + overflow) 519 These can be easily collected into a BER-encoded octet string, 520 and would be read and referred to as a 'distribution.' 522 5. Extensions to the Rules Table, Attribute Numbers 524 The Rules Table of "old-style" attributes will be extended for the 525 new flow types. A list of actions, and keywords, such as "ToBitRate", 526 "ToPacketSize", etc. will be developed and used to inform an RTFM 527 meter to collect a set of extended values for a particular flow (or set of flows). 529 Note: An implementation suggestion. Value 65 is used for 'Distributions,' 530 which has one bit set for each distribution-valued attribute present 531 for the flow, using bit 0 for attribute 66, bit 1 for attribute 67, etc. 533 Here are ten possible distribution-valued attributes numbered according 534 to RTFM WG consensus at the 1997 meeting in Munich: 536 ToPacketSize(66) size of PDUs in bytes (i.e. number 537 FromPacketSize(67) of bytes actually transmitted) 539 ToInterarrivalTime(68) microseconds between successive packets 540 FromInterarrivalTime(69) travelling in the same direction 542 ToTurnaroundTime(70) microseconds between successive packets 543 FromTurnaroundTime(71) travelling in opposite directions 545 ToBitRate(72) short-term flow rate in bits per second 546 FromBitRate(73) Parameter 1 = rate interval in seconds 548 ToPDURate(74) short-term flow rate in PDUs per second 549 FromPDURate(75) Parameter 1 = rate interval in seconds 551 (76 .. 97) other distributions 553 It seems reasonable to allocate a further group of numbers 554 for the IIS attributes described above - 556 QoSService(98) 557 QoSStyle(99) 558 QoSRate(100) 559 QoSSlackTerm(101) 560 QoSTokenBucketRate(102) 562 The following attributes have also been implemented in NetFlowMet, a 563 version of the NeTraMet meter - 565 MeterID(105) Integer identifying the router producing NetFlow 566 data (needed when NetFlowMet takes data 567 from several routers) 568 SourceASN(106) Autonomous System Number for flow's source 569 SourcePrefix(107) CIDR width used by router for determining 570 flow's source network 571 DestASN(108) Autonomous System Number for flow's destination 572 DestPrefix(109) CIDR width used by router for determining 573 flow's destination network 575 Some of the above, e.g. SourceASN and DestASN, might sensibly be 576 allocated attribute numbers below 64, making them part of the 'base' 577 RTFM meter attributes. 579 To support use of the RTFM meter as an 'Edge Device' for implementing 580 Differentiated Services, and/or for metering traffic carried via such 581 services, two more attributes will be useful: 583 SourceDSfield(118) DS field value for S->D packets 584 DestDSfield(119) DS field value for D->S packets 586 6. Security Considerations 588 The attributes considered in this document represent properties 589 of traffic flows; they do not present any security issues in 590 themselves. The attributes may, however, be used in measuring the 591 behaviour of traffic flows, and the collected traffic flow data 592 could be of considerable value. 593 Suitable precautions should be taken to keep such data safe. 595 7. Acknowledgements 597 8. Author's Address: 599 Sig Handelman 600 IBM Research Division 601 Hawthorne, NY 602 Phone: 1-914-784-7626 603 E-mail: swhandel@us.ibm.com 605 Nevil Brownlee 606 The University of Auckland 607 New Zealand 608 Phone: +64 9 373 7599 x8941 609 E-mail: n.brownlee@auckland.ac.nz 611 Greg Ruth 612 GTE Laboratories 613 Waltham, MA 614 Phone: 1 781 466 2448 615 E-mail: grr1@gte.com 617 Stephen Stibler 618 IBM Research Division 619 Hawthorne, NY 620 Phone: 1-914-784-7191 621 E-mail: stibler@us.ibm.com 623 9. References: 625 [1] Brownlee, N., Mills, C., Ruth, G.: "Traffic Flow Measurement: 626 Architecture", RFC 2063, 1997 628 [2] Wroclawski, J.: "The Use of RSVP with IETF Integrated Services" 630 [3] Almes, G. et al: "Framework for IP Performance Metrics" Internet 631 Draft. July 1996 633 [4] Claffy, K., Braun, H-W, Polyzos, G.: "A Parameterizable 634 Methodology for Internet Traffic Flow Profiling," IEEE Journal on 635 Selected Areas in Communications, Vol. 13, No. 8, October 1995. 637 [5] Mills, C., Ruth, G.: "Internet Accounting Background," RFC 1272, 638 1992. 640 [6] Waldbusser, S.: "Remote Network Monitoring Management Information 641 Base," RFC 1757, 1995, and RFC 2021, 1997. 643 [7] Brownlee, N: "Traffic Flow Measurement: Meter MIB", RFC 2064, 644 1997 646 [8] Maiocchi, S: "NeTraMet & NeMaC for IIS Accounting: User's Guide", 647 CEFRIEL, Milan, 5 May 1998 649 [9] Shenker, S., Partridge, C., Guerin, R.: "Specification of 650 Guaranteed Quality of Service," RFC 2212, 1997.