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Versions: 00 01 02 03 04 draft-ietf-ippm-multipoint-alt-mark

IPPM Working Group                                      G. Fioccola, Ed.
Internet-Draft                                          M. Cociglio, Ed.
Intended status: Experimental                             Telecom Italia
Expires: May 3, 2018                                       A. Sapio, Ed.
                                                           R. Sisto, Ed.
                                                   Politecnico di Torino
                                                        October 30, 2017


 Multipoint Alternate Marking method for passive and hybrid performance
                               monitoring
               draft-fioccola-ippm-multipoint-alt-mark-01

Abstract

   The Alternate Marking method, as presented in
   [I-D.ietf-ippm-alt-mark], can be applied only to point-to-point flows
   because it assumes that all the packets of the flow measured on one
   node are measured again by a single second node.  This document aims
   to generalize and expand this methodology to measure any kind of
   unicast flows, whose packets can follow several different paths in
   the network, in wider terms a multipoint-to-multipoint network.  For
   this reason the technique here described is called Multipoint
   Alternate Marking.  Some definitions here introduced extend the scope
   of RFC 5644 [RFC5644] in the context of alternate marking schema.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 3, 2018.



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Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Correlation with RFC5644  . . . . . . . . . . . . . . . . . .   3
   3.  Flow classification . . . . . . . . . . . . . . . . . . . . .   3
   4.  Multipoint Performance Measurement  . . . . . . . . . . . . .   6
     4.1.  Monitoring Network  . . . . . . . . . . . . . . . . . . .   6
     4.2.  Multipoint Packet Loss  . . . . . . . . . . . . . . . . .   7
     4.3.  Network Clustering  . . . . . . . . . . . . . . . . . . .   8
     4.4.  Multipoint Delay and Jitter . . . . . . . . . . . . . . .  10
       4.4.1.  Single and Double Marking measurement . . . . . . . .  10
       4.4.2.  Mean Delay and Jitter . . . . . . . . . . . . . . . .  11
       4.4.3.  Hashing selection method  . . . . . . . . . . . . . .  11
   5.  Examples of application . . . . . . . . . . . . . . . . . . .  12
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The Alternate Marking methodology described in
   [I-D.ietf-ippm-alt-mark] has the property to synchronize measurements
   in different points maintaining the coherence of the counters.  So it
   is possible to show what is happening in every marking period for
   each monitored flow.  The monitoring parameters are the packet
   counter and timestamps of a flow for each marking period.

   There are some applications of the alternate marking method where
   there are a lot of monitored flows and nodes.



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   For instance, by considering n measurement points and n monitored
   flows, the order of magnitude of the packet counters for each time
   interval is n*n*2 (1 per color).

   Multipoint Alternate Marking aims to reduce this value and makes the
   performance monitoring more flexible in case a detailed analysis is
   not needed.  It can be applied only to unicast flows.

   In some circumstances it is possible to monitor a Multipoint Network
   by analyzing the Network Clustering, without examining in depth.  In
   case there is packet loss or the delay is too high the filtering
   criteria could be specified more in order to perform a per flow
   detailed analysis, as described in [I-D.ietf-ippm-alt-mark].

   An application could be the software defined network (SDN) paradigm
   where the SDN Controllers are the brains of the network and can
   manage flow control to the switches and routers and, in the same way,
   can calibrate the performance measurements depending on the
   necessity.

2.  Correlation with RFC5644

   RFC 5644 [RFC5644] is limited to active measurements using a single
   source packet or stream, and observations of corresponding packets
   along the path (spatial), at one or more destinations (one-to-group),
   or both.  Instead, the scope of this memo is to define multiparty
   metrics for passive and hybrid measurements in a group-to-group
   topology with multiple sources and destinations.

   RFC 5644 [RFC5644] introduces metric names that can be reused also
   here but have to be extended and rephrased to be applied to the
   alternate marking schema:

   o  the multiparty metrics are not only one-to-group metrics but can
      be also group-to-group metrics;

   o  the spatial metrics, used for measuring the performance of
      segments of a source to destination path, are applied here to
      group-to-group segments (called Clusters).

3.  Flow classification

   A flow is identified by all the packets having a set of common
   characteristics.  This definition is inspired by RFC 7011 [RFC7011].

   As an example, by considering a flow as all the packets sharing the
   same source IP address or the same destination IP address, it is easy
   to understand that the resulting pattern will not be a point-to-point



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   connection, but a point-to-multipoint or multipoint-to-point
   connection.

   In general a flow can be defined by a set of selection rules used to
   match a subset of the packets processed by the network device.  These
   rules specify a set of headers fields (Identification Fields) and the
   relative values that must be found in matching packets.

   The choice of the identification fields directly affects the type of
   paths that the flow would follow in the network.  In fact, it is
   possible to relate a set of identification fields with the pattern of
   the resulting graphs, as listed in Figure 1.


          point-to-point single path
              +------+      +------+      +------+
          ---<>  R1  <>----<>  R2  <>----<>  R3  <>---
              +------+      +------+      +------+

          point-to-point multipath
                           +------+
                          <>  R2  <>
                         / +------+ \
                        /            \
              +------+ /              \ +------+
          ---<>  R1  <>                <>  R4  <>---
              +------+ \              / +------+
                        \            /
                         \ +------+ /
                          <>  R3  <>
                           +------+

          point-to-multipoint
                                      +------+
                                     <>  R4  <>---
                                    / +------+
                          +------+ /
                         <>  R2  <>
                        / +------+ \
              +------+ /            \ +------+
          ---<>  R1  <>              <>  R5  <>---
              +------+ \              +------+
                        \ +------+
                         <>  R3  <>
                          +------+ \
                                    \ +------+
                                     <>  R6  <>---
                                      +------+



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          multipoint-to-point
              +------+
          ---<>  R1  <>
              +------+ \
                        \ +------+
                        <>  R4  <>
                        / +------+ \
              +------+ /            \ +------+
          ---<>  R2  <>              <>  R4  <>---
              +------+              / +------+
                          +------+ /
                         <>  R5  <>
                        / +------+
              +------+ /
          ---<>  R3  <>
              +------+

          multipoint-to-multipoint
              +------+                +------+
          ---<>  R1  <>              <>  R6  <>---
              +------+ \            / +------+
                        \ +------+ /
                         <>  R4  <>
                          +------+ \
              +------+              \ +------+
          ---<>  R2  <>             <>  R7  <>---
              +------+ \            / +------+
                        \ +------+ /
                         <>  R5  <>
                        / +------+ \
              +------+ /            \ +------+
          ---<>  R3  <>              <>  R8  <>---
              +------+                +------+



                       Figure 1: Flow classification

   A TCP 5-tuple usually identifies flows following either a single path
   or a point-to-point multipath (in case of load balancing).  On the
   contrary, a single source address selects flows following a point-to-
   multipoint, while a multipoint-to-point can be the result of a
   matching on a single destination address.  In case a selection rule
   and its reverse are used for bidirectional measurements, they can
   correspond to a point-to-multipoint in one direction and a
   multipoint-to-point in the opposite direction.





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   In this way the flows to be monitored are selected into the
   monitoring points using packet selection rules, that can also change
   the pattern of the monitored network.

   The alternate marking method is applicable only to a single path (and
   partially to a one-to-one multipath), so the extension proposed in
   this document is suitable also for the most general case of
   multipoint-to-multipoint, which embraces all the other patterns of
   Figure 1.

4.  Multipoint Performance Measurement

   By Using the "traditional" alternate marking method only point-to-
   point paths can be monitored.  To have an IP (TCP/UDP) flow that
   follows a point-to-point path we have to define, with a specific
   value, 5 identification fields (IP Source, IP Destination, Transport
   Protocol, Source Port, Destination Port).

   Multipoint Alternate Marking enables the performance measurement for
   multipoint flows selected by identification fields without any
   constraints (even the entire network production traffic).  It is also
   possible to use multiple marking points for the same monitored flow.

4.1.  Monitoring Network

   The Monitoring Network is deduced from the Production Network, by
   identifying the nodes of the graph, that are the measurement points,
   and the links, that are the connections between measurement points.

   So a model of the monitoring network can be built according to the
   alternate marking method: the monitored interfaces and links are
   identified.  Only the measurement points and links where the traffic
   has flowed have to be represented in the graph.

   The following figure shows a simple example of a Monitoring Network
   graph:















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                                                    +------+
                                                   <>  R6  <>---
                                                  / +------+
                           +------+     +------+ /
                          <>  R2  <>---<>  R4  <>
                         / +------+ \   +------+ \
                        /            \            \ +------+
              +------+ /   +------+   \ +------+   <>  R7  <>---
          ---<>  R1  <>---<>  R3  <>---<>  R5  <>   +------+
              +------+ \   +------+ \   +------+ \
                        \            \            \ +------+
                         \            \            <>  R8  <>---
                          \            \            +------+
                           \            \
                            \            \ +------+
                             \            <>  R9  <>---
                              \            +------+
                               \
                                \ +------+
                                 <>  R10 <>---
                                  +------+


                       Figure 2: Monitoring Network

   Each monitoring point is characterized by the packet counter that
   refers only to a marking period of the monitored flow.

   The same is applicable also for the delay but it will be described in
   the following sections.

4.2.  Multipoint Packet Loss

   Since all the packets of the considered flow leaving the network have
   previously entered the network, the number of packets counted by all
   the input nodes is always greater or equal than the number of packets
   counted by all the output nodes.

   And in case of no packet loss occurring in the marking period, if all
   the input and output points of the network domain to be monitored are
   measurement points, the number of packets is the same on all the
   ingress interfaces and on all the egress interfaces.  The
   intermediate measurement points have only the task to split the
   measurement.

   It is possible to define the Network Packet Loss (for 1 flow, for 1
   period): <<In a packet network, the number of lost packets is the
   number of packets counted by the input nodes minus the number of



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   packets counted by the output nodes>>.  This is true for every packet
   flow in each marking period.

   The Monitored Network Packet Loss with n input nodes and m output
   nodes is given by:

   PL = (PI1 + PI2 +...+ PIn) - (POi + PO2 +...+ POm)

   where:

   PL is the Network Packet Loss (number of lost packets)

   PIi is the Number of packets flowed through the i-th Input node in
   this period

   POj is the Number of packets flowed through the j-th Output node in
   this period

4.3.  Network Clustering

   The previous Equation can determine the number of packets lost
   globally in the monitored network, exploiting only the data provided
   by the counters in the input and output nodes.

   In addition it is also possible to leverage the data provided by the
   other counters in the network to converge on the smallest
   identifiable subnetworks where the losses occur.  These subnetworks
   are named Clusters.

   A Cluster is a subnetwork of the entire Monitoring Network graph that
   still satisfies the packet loss equation where PL in this case is the
   number of packets lost in the Cluster.

   For this reason a Cluster should contain all the arcs emanating from
   its input nodes and all the arcs terminating at its output nodes.
   This ensures that we can count all the packets (and only those)
   exiting an input node again at the output node, whatever path they
   follow.

   In a completely monitored network (a network where every network
   interface is monitored), each network device corresponds to a Cluster
   and each physical link corresponds to two Clusters (one for each
   direction).

   Clusters can have different sizes depending on flow filtering
   criteria adopted.





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   Moreover, sometimes Clusters can be simplified; for example when two
   monitored interfaces are divided by a single router (one is the input
   interface and the other is the output interface and the router has
   only these two interfaces), instead of counting exactly twice, upon
   entering and leaving, in this case it is possible to consider a
   single measurement point.

   In our monitoring network graph example it is possible to identify 4
   Clusters:


          Cluster 1
                           +------+
                          <>  R2  <>---
                         / +------+
                        /
              +------+ /   +------+
          ---<>  R1  <>---<>  R3  <>---
              +------+ \   +------+
                        \
                         \
                          \
                           \
                            \
                             \
                              \
                               \
                                \ +------+
                                 <>  R10 <>---
                                  +------+


          Cluster 2
              +------+     +------+
          ---<>  R2  <>---<>  R4  <>---
              +------+ \   +------+
                        \
              +------+   \ +------+
          ---<>  R3  <>---<>  R5  <>---
              +------+ \   +------+
                        \
                         \
                          \
                           \
                            \ +------+
                             <>  R9  <>---
                              +------+




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          Cluster 3
                          +------+
                         <>  R6  <>---
                        / +------+
              +------+ /
          ---<>  R4  <>
              +------+ \
                        \ +------+
                         <>  R7  <>---
                          +------+


          Cluster 4
              +------+
          ---<>  R5  <>
              +------+ \
                        \ +------+
                         <>  R8  <>---
                          +------+


                        Figure 3: Clusters example

   There are Clusters with more than 2 nodes and two-nodes Clusters.  In
   the two-nodes Clusters the loss is on the link (Cluster 4).  In more-
   than-2-nodes Clusters the loss is on the Cluster but we cannot know
   in which link (Cluster 1, 2, 3).

   Obviously, by combining some Clusters in a new connected subnetwork
   (called Super Cluster) the Packet Loss Rule is still true.

4.4.  Multipoint Delay and Jitter

   The same line of reasoning can be applied to Delay and Jitter.

4.4.1.  Single and Double Marking measurement

   Delay and Jitter measurements relative to a picked packet (both
   single and double marked) cannot be performed in the Multipoint
   scenario, since they would not be representative of the entire flow.
   The packets can follow different paths with various delays and in
   general it is very difficult to recognize a marked packet in a
   multipoint-to-multipoint path.








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4.4.2.  Mean Delay and Jitter

   Mean delay and jitter measurements can also be generalized to the
   case of multipoint flows.  It is possible to compute the average one-
   way delay of packets, in one block, in a cluster or in the entire
   monitored network.

   The average latency can be measured as the difference between the
   weighted averages of the mean timestamps of the sets of output and
   input nodes.

4.4.3.  Hashing selection method

   RFC 5474 [RFC5474] and RFC 5475 [RFC5475] introduce sampling and
   filtering techniques for IP Packet Selection.

   The hash-based selection methodologies for delay measurement can work
   in a multipoint-to-multipoint path and can be used both coupled to
   mean delay or stand alone.

   [I-D.mizrahi-ippm-compact-alternate-marking] introduces how to use
   the Hash method combined with alternate maring method for point-to-
   point flows.  It is also called Mixed Hashed Marking: the coupling of
   marking method and hashing technique is very useful because the
   marking batches anchor the samples selected with hashing and this
   simplifies the correlation of the hashing packets along the path.

   It is possible to use a basic hash or a dynamic hash method.  One of
   the challenges of the basic approach is that the frequency of the
   sampled packets may vary considerably.  Fort this reason the dynamic
   approach has been introduced for point-to-point flow in order to have
   the desired and almost fixed number of samples for each measurement
   period.  In the hash-based sampling, alternate marking is used to
   create periods, so that hash-based samples are divided into batches,
   allowing to anchor the selected samples to their period.  Moreover in
   the dynamic hash-based sampling, by dynamically adapting the length
   of the hash value, the number of samples is bounded in each marking
   period.  This can be realized by choosing the maximum number of
   samples (NMAX) to be catched in a marking period.  The algorithm
   starts with only few hash bits, that permit to select a greater
   percentage of packets (e.g. with 0 bit of hash all the packets are
   sampled, with 1 bit of hash half of the packets are sampled, and so
   on).  When the number of selected packets reaches NMAX, a hashing bit
   is added.  As a consequence, the sampling proceeds at half of the
   original rate and also the packets already selected that don't match
   the new hash are discarded.  This step can be repeated iteratively.
   It is assumed that each sample includes the timestamp (used for DM)
   and the hash value, allowing the management system to match the



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   samples received from the two MPs.  The dynamic process statistically
   converges at the end of a marking period and the final number of
   selected samples is between NMAX/2 and NMAX.  Therefore, the dynamic
   approach paces the sampling rate, allowing to bound the number of
   sampled packets per sampling period.

   In a multipoint environment the behaviour is similar to point-to
   point flow.  In particular, in the context of multipoint-to-
   multipoint flow, the dynamic hash could be the solution to perform
   delay measurements on specific packets and to overcome the single and
   double marking limitations.

   The management system receives the samples including the timestamps
   and the hash value from all the MPs, and this happens both for point-
   to-point and for multipoint-to-multipoint flow.  Then the longest
   hash used by MPs is deduced and it is applied to couple timestamps of
   same packets of 2 MPs of a point-to-point path or of input and output
   MPs of a Cluster (or a Super Cluster or the entire network).  But
   some considerations are needed: if there isn't packet loss the set of
   input samples is always equal to the set of output samples.  In case
   of packet loss the set of output samples can be a subset of input
   samples but the method still works because, at the end, it is easy to
   couple the input and output timestamps of each catched packet using
   the hash (in particular the "unused part of the hash" that should be
   different for each packet).

5.  Examples of application

   There are three application fields where it may be useful to take
   into consideration the Multipoint Alternate Marking:

   o  VPN: The IP traffic is selected on IP source basis in both
      directions.  At the end point WAN interface all the output traffic
      is counted in a single flow.  The input traffic is composed by all
      the other flows aggregated for source address.  So, by considering
      n end-points, the monitored flows are n (each flow with 1 ingress
      point and (n-1) egress points) instead of n*(n-1) flows (each
      flow, with 1 ingress point and 1 egress point);

   o  Mobile Backhaul: LTE traffic is selected, in the Up direction, by
      the EnodeB source address and, in Down direction, by the EnodeB
      destination address because the packets are sent from the Mobile
      Packet Core to the EnodeB.  So the monitored flow is only one per
      EnodeB in both directions;

   o  OTT(Over The Top) services: The traffic is selected, in the Down
      direction by the source addresses of the packets sent by OTT
      Servers.  In the opposite direction (Up) by the destination IP



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      addresses of the same Servers.  So the monitoring is based on a
      single flow per OTT Servers in both directions.

6.  Security Considerations

   tbc

7.  Acknowledgements

   tbc

8.  IANA Considerations

   tbc

9.  References

9.1.  Normative References

   [I-D.ietf-ippm-alt-mark]
              Fioccola, G., Capello, A., Cociglio, M., Castaldelli, L.,
              Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
              "Alternate Marking method for passive and hybrid
              performance monitoring", draft-ietf-ippm-alt-mark-13 (work
              in progress), October 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5644]  Stephan, E., Liang, L., and A. Morton, "IP Performance
              Metrics (IPPM): Spatial and Multicast", RFC 5644,
              DOI 10.17487/RFC5644, October 2009,
              <https://www.rfc-editor.org/info/rfc5644>.

9.2.  Informative References

   [I-D.mizrahi-ippm-compact-alternate-marking]
              Mizrahi, T., Arad, C., Fioccola, G., Cociglio, M., Chen,
              M., Zheng, L., and G. Mirsky, "Compact Alternate Marking
              Methods for Passive Performance Monitoring", draft-
              mizrahi-ippm-compact-alternate-marking-00 (work in
              progress), October 2017.







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   [RFC5474]  Duffield, N., Ed., Chiou, D., Claise, B., Greenberg, A.,
              Grossglauser, M., and J. Rexford, "A Framework for Packet
              Selection and Reporting", RFC 5474, DOI 10.17487/RFC5474,
              March 2009, <https://www.rfc-editor.org/info/rfc5474>.

   [RFC5475]  Zseby, T., Molina, M., Duffield, N., Niccolini, S., and F.
              Raspall, "Sampling and Filtering Techniques for IP Packet
              Selection", RFC 5475, DOI 10.17487/RFC5475, March 2009,
              <https://www.rfc-editor.org/info/rfc5475>.

   [RFC7011]  Claise, B., Ed., Trammell, B., Ed., and P. Aitken,
              "Specification of the IP Flow Information Export (IPFIX)
              Protocol for the Exchange of Flow Information", STD 77,
              RFC 7011, DOI 10.17487/RFC7011, September 2013,
              <https://www.rfc-editor.org/info/rfc7011>.

Authors' Addresses

   Giuseppe Fioccola (editor)
   Telecom Italia
   Via Reiss Romoli, 274
   Torino  10148
   Italy

   Email: giuseppe.fioccola@telecomitalia.it


   Mauro Cociglio (editor)
   Telecom Italia
   Via Reiss Romoli, 274
   Torino  10148
   Italy

   Email: mauro.cociglio@telecomitalia.it


   Amedeo Sapio (editor)
   Politecnico di Torino
   Corso Duca degli Abruzzi, 24
   Torino  10129
   Italy

   Email: amedeo.sapio@polito.it








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   Riccardo Sisto (editor)
   Politecnico di Torino
   Corso Duca degli Abruzzi, 24
   Torino  10129
   Italy

   Email: riccardo.sisto@polito.it












































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