draft-ietf-ippm-multipoint-alt-mark-06.txt   draft-ietf-ippm-multipoint-alt-mark-07.txt 
IPPM Working Group G. Fioccola, Ed. IPPM Working Group G. Fioccola, Ed.
Internet-Draft Huawei Technologies Internet-Draft Huawei Technologies
Intended status: Experimental M. Cociglio Intended status: Experimental M. Cociglio
Expires: August 27, 2020 Telecom Italia Expires: September 10, 2020 Telecom Italia
A. Sapio A. Sapio
R. Sisto R. Sisto
Politecnico di Torino Politecnico di Torino
February 24, 2020 March 9, 2020
Multipoint Alternate Marking method for passive and hybrid performance Multipoint Alternate Marking method for passive and hybrid performance
monitoring monitoring
draft-ietf-ippm-multipoint-alt-mark-06 draft-ietf-ippm-multipoint-alt-mark-07
Abstract Abstract
The Alternate Marking method, as presented in RFC 8321, can be The Alternate Marking method, as presented in RFC 8321, can be
applied only to point-to-point flows because it assumes that all the 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 packets of the flow measured on one node are measured again by a
single second node. This document aims to generalize and expand this single second node. This document aims to generalize and expand this
methodology to measure any kind of unicast flows, whose packets can methodology to measure any kind of unicast flows, whose packets can
follow several different paths in the network, in wider terms a follow several different paths in the network, in wider terms a
multipoint-to-multipoint network. For this reason the technique here multipoint-to-multipoint network. For this reason the technique here
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 27, 2020. This Internet-Draft will expire on September 10, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Correlation with RFC5644 . . . . . . . . . . . . . . . . . . 4 2. Correlation with RFC5644 . . . . . . . . . . . . . . . . . . 4
3. Flow classification . . . . . . . . . . . . . . . . . . . . . 4 3. Flow classification . . . . . . . . . . . . . . . . . . . . . 4
4. Multipoint Performance Measurement . . . . . . . . . . . . . 7 4. Multipoint Performance Measurement . . . . . . . . . . . . . 7
4.1. Monitoring Network . . . . . . . . . . . . . . . . . . . 7 4.1. Monitoring Network . . . . . . . . . . . . . . . . . . . 7
5. Multipoint Packet Loss . . . . . . . . . . . . . . . . . . . 8 5. Multipoint Packet Loss . . . . . . . . . . . . . . . . . . . 8
6. Network Clustering . . . . . . . . . . . . . . . . . . . . . 9 6. Network Clustering . . . . . . . . . . . . . . . . . . . . . 10
6.1. Algorithm for Cluster partition . . . . . . . . . . . . . 10 6.1. Algorithm for Cluster partition . . . . . . . . . . . . . 10
7. Timing Aspects . . . . . . . . . . . . . . . . . . . . . . . 13 7. Timing Aspects . . . . . . . . . . . . . . . . . . . . . . . 14
8. Multipoint Delay and Delay Variation . . . . . . . . . . . . 15 8. Multipoint Delay and Delay Variation . . . . . . . . . . . . 15
8.1. Delay measurements on multipoint paths basis . . . . . . 15 8.1. Delay measurements on multipoint paths basis . . . . . . 16
8.1.1. Single Marking measurement . . . . . . . . . . . . . 15 8.1.1. Single Marking measurement . . . . . . . . . . . . . 16
8.2. Delay measurements on single packets basis . . . . . . . 15 8.2. Delay measurements on single packets basis . . . . . . . 16
8.2.1. Single and Double Marking measurement . . . . . . . . 15 8.2.1. Single and Double Marking measurement . . . . . . . . 16
8.2.2. Hashing selection method . . . . . . . . . . . . . . 16 8.2.2. Hashing selection method . . . . . . . . . . . . . . 17
9. An Intelligent Performance Management approach . . . . . . . 18 9. An Intelligent Performance Management approach . . . . . . . 18
10. Examples of application . . . . . . . . . . . . . . . . . . . 19 10. Examples of application . . . . . . . . . . . . . . . . . . . 20
11. Security Considerations . . . . . . . . . . . . . . . . . . . 20 11. Security Considerations . . . . . . . . . . . . . . . . . . . 21
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
14.1. Normative References . . . . . . . . . . . . . . . . . . 20 14.1. Normative References . . . . . . . . . . . . . . . . . . 21
14.2. Informative References . . . . . . . . . . . . . . . . . 20 14.2. Informative References . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
The alternate marking method, as described in RFC 8321 [RFC8321], is The alternate marking method, as described in RFC 8321 [RFC8321], is
applicable to a point-to-point path; so the extension proposed in applicable to a point-to-point path; so the extension proposed in
this document explains the most general case of multipoint-to- this document explains the most general case of multipoint-to-
multipoint path and enables flexible and adaptive performance multipoint path and enables flexible and adaptive performance
measurements in a managed network. measurements in a managed network.
The Alternate Marking methodology described in RFC 8321 [RFC8321] has The Alternate Marking methodology described in RFC 8321 [RFC8321] has
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multipoint, while a multipoint-to-point can be the result of a multipoint, while a multipoint-to-point can be the result of a
matching on a single destination address. In case a selection rule matching on a single destination address. In case a selection rule
and its reverse are used for bidirectional measurements, they can and its reverse are used for bidirectional measurements, they can
correspond to a point-to-multipoint in one direction and a correspond to a point-to-multipoint in one direction and a
multipoint-to-point in the opposite direction. multipoint-to-point in the opposite direction.
In this way the flows to be monitored are selected into the In this way the flows to be monitored are selected into the
monitoring points using packet selection rules, that can also change monitoring points using packet selection rules, that can also change
the pattern of the monitored network. the pattern of the monitored network.
Note that, more in general, the flow can be defined at different
levels based on the encapsulation considered and additional
conditions that are not in the packet header can also be included as
part of matching criteria.
The alternate marking method is applicable only to a single path (and The alternate marking method is applicable only to a single path (and
partially to a one-to-one multipath), so the extension proposed in partially to a one-to-one multipath), so the extension proposed in
this document is suitable also for the most general case of this document is suitable also for the most general case of
multipoint-to-multipoint, which embraces all the other patterns of multipoint-to-multipoint, which embraces all the other patterns of
Figure 1. Figure 1.
point-to-point single path point-to-point single path
+------+ +------+ +------+ +------+ +------+ +------+
---<> R1 <>----<> R2 <>----<> R3 <>--- ---<> R1 <>----<> R2 <>----<> R3 <>---
+------+ +------+ +------+ +------+ +------+ +------+
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The same is applicable also for the delay but it will be described in The same is applicable also for the delay but it will be described in
the following sections. the following sections.
5. Multipoint Packet Loss 5. Multipoint Packet Loss
Since all the packets of the considered flow leaving the network have Since all the packets of the considered flow leaving the network have
previously entered the network, the number of packets counted by all previously entered the network, the number of packets counted by all
the input nodes is always greater or equal than the number of packets the input nodes is always greater or equal than the number of packets
counted by all the output nodes. counted by all the output nodes.
And in case of no packet loss occurring in the marking period, if all The assumption is the use of the Alternate Marking Method. And in
the input and output points of the network domain to be monitored are 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 sum of the number of packets on all the measurement points, the sum of the number of packets on all the
ingress interfaces equals the number on egress interfaces for the ingress interfaces equals the number on egress interfaces for the
monitored flow. In this circumstance, if no packet loss occurs, the monitored flow. In this circumstance, if no packet loss occurs, the
intermediate measurement points have only the task to split the intermediate measurement points have only the task to split the
measurement. measurement.
It is possible to define the Network Packet Loss of one monitored It is possible to define the Network Packet Loss of one monitored
flow for a single period: <<In a packet network, the number of lost flow for a single period: <<In a packet network, the number of lost
packets is the number of packets counted by the input nodes minus the packets is the number of packets counted by the input nodes minus the
number of packets counted by the output nodes>>. This is true for number of packets counted by the output nodes>>. This is true for
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criteria adopted. criteria adopted.
Moreover, sometimes Clusters can be optionally simplified. For Moreover, sometimes Clusters can be optionally simplified. For
example when two monitored interfaces are divided by a single router example when two monitored interfaces are divided by a single router
(one is the input interface and the other is the output interface and (one is the input interface and the other is the output interface and
the router has only these two interfaces), instead of counting the router has only these two interfaces), instead of counting
exactly twice, upon entering and leaving, it is possible to consider exactly twice, upon entering and leaving, it is possible to consider
a single measurement point (in this case we do not care of the a single measurement point (in this case we do not care of the
internal packet loss of the router). internal packet loss of the router).
It is worth highlighting that it might also be convenient to define
Clusters based on the topological information and applicable to all
the possible flows in the monitored network.
6.1. Algorithm for Cluster partition 6.1. Algorithm for Cluster partition
A simple algorithm can be applied in order to split our monitoring A simple algorithm can be applied in order to split our monitoring
network into Clusters. It is a two-step algorithm: network into Clusters. It is a two-step algorithm:
o Group the links where there is the same starting node; o Group the links where there is the same starting node;
o Join the grouped links with at least one ending node in common. o Join the grouped links with at least one ending node in common.
After the application of the previous two steps, each one of the After the application of the previous two steps, each one of the
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Obviously, by combining some Clusters in a new connected subnetwork Obviously, by combining some Clusters in a new connected subnetwork
(called Super Cluster) the Packet Loss Rule is still true. (called Super Cluster) the Packet Loss Rule is still true.
In this way in a very large network there is no need to configure In this way in a very large network there is no need to configure
detailed filter criteria to inspect the traffic. You can check detailed filter criteria to inspect the traffic. You can check
multipoint network and only in case of problems you can go deep with multipoint network and only in case of problems you can go deep with
a step-by-step cluster analysis, but only for the cluster or a step-by-step cluster analysis, but only for the cluster or
combination of clusters where the problem happens. combination of clusters where the problem happens.
In summary, once defined a flow, the algorithm to build the Cluster
Partition considers all the possible links and nodes crossed by the
given flow, even if there is no traffic. It is based on topological
information. So, if the flow do not enter or traverse all the nodes,
the counters has a non-zero value for the involved nodes, while a
zero value for the other nodes without traffic, but, in the end all
the formulas are still valid.
The algorithm described above is an Iterative clustering algorithm, The algorithm described above is an Iterative clustering algorithm,
but it is also possible to apply a Recursive clustering algorithm by but it is also possible to apply a Recursive clustering algorithm by
using the node-node adjacency matrix representation. using the node-node adjacency matrix representation.
The complete and mathematical analysis of the possible Algorithms for The complete and mathematical analysis of the possible Algorithms for
Cluster partition, including the considerations in terms of Cluster partition, including the considerations in terms of
efficiency and a comparison between the different methods, is in the efficiency and a comparison between the different methods, is in the
paper [IEEE-ACM-ToN-MPNPM]. paper [IEEE-ACM-ToN-MPNPM].
7. Timing Aspects 7. Timing Aspects
It is important to consider the timing aspects, since out of order It is important to consider the timing aspects, since out of order
packets happen and have to be handled as well as described in RFC packets happen and have to be handled as well as described in RFC
8321 [RFC8321]. But, in a multi-source situation an additional issue 8321 [RFC8321]. But, in a multi-source situation an additional issue
has to be considered. has to be considered. With multipoint path, the egress nodes will
receive alternate marked packets in random order from different
ingress nodes, and this must not affect the measurement.
So, if we analyse a multipoint-to-multipoint path with more than one So, if we analyse a multipoint-to-multipoint path with more than one
marking node, it is important to recognize the reference measurement marking node, it is important to recognize the reference measurement
interval. In general the measurement interval for describing the interval. In general the measurement interval for describing the
results is the interval of the marking node that is more aligned with results is the interval of the marking node that is more aligned with
the start of the measurement, as reported in the following figure. the start of the measurement, as reported in the following figure.
Note that the mark switching approach based on a fixed timer is Note that the mark switching approach based on a fixed timer is
considered in this document. considered in this document.
time -> start stop time -> start stop
T(R1) |-------------| T(R1) |-------------|
T(R2) |-------------| T(R2) |-------------|
T(R3) |------------| T(R3) |------------|
Figure 4: Measurement Interval Figure 4: Measurement Interval
In the figure it is assumed that the node with the earliest clock In the figure it is assumed that the node with the earliest clock
(R1) identifies the right starting and ending time of the (R1) identifies the right starting and ending time of the
measurement, but it is just an assumption and other possibilities measurement, but it is just an assumption and other possibilities
could occurr. So, in this case, T(R1) is the measurement interval could occur. So, in this case, T(R1) is the measurement interval and
and its recognition is essential in order to be compatible and make its recognition is essential in order to be compatible and make
comparison with other active/passive/hybrid Packet Loss metrics. comparison with other active/passive/hybrid Packet Loss metrics.
Therefore, when we expand to multipoint-to-multipoint flows, we have Therefore, when we expand to multipoint-to-multipoint flows, we have
to consider that all source nodes mark the traffic and this adds more to consider that all source nodes mark the traffic and this adds more
complexity. complexity.
Regarding the timing aspects of the methodology, RFC 8321 [RFC8321] Regarding the timing aspects of the methodology, RFC 8321 [RFC8321]
already describes two contributions that are taken into account: the already describes two contributions that are taken into account: the
clock error between network devices and the network delay between clock error between network devices and the network delay between
measurement points. measurement points.
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can reduce the order of magnitude of the packet counters. This can reduce the order of magnitude of the packet counters. This
allows an SDN Orchestrator to supervise, control and manage PM in allows an SDN Orchestrator to supervise, control and manage PM in
large networks. large networks.
The monitoring network can be considered as a whole or can be split The monitoring network can be considered as a whole or can be split
in Clusters, that are the smallest subnetworks (group-to-group in Clusters, that are the smallest subnetworks (group-to-group
segments), maintaining the packet loss property for each subnetwork. segments), maintaining the packet loss property for each subnetwork.
They can also be combined in new connected subnetworks at different They can also be combined in new connected subnetworks at different
levels depending on the detail we want to achieve. levels depending on the detail we want to achieve.
An SDN Controller can calibrate Performance Measurements since it is An SDN Controller or a Network Management System (NMS) can calibrate
aware of the network topology. It can start without examining in Performance Measurements since it is aware of the network topology.
depth. In case of necessity (packet loss is measured or the delay is It can start without examining in depth. In case of necessity
too high), the filtering criteria could be immediately specified more (packet loss is measured or the delay is too high), the filtering
in order to perform a partition of the network by using Clusters and/ criteria could be immediately specified more in order to perform a
or different combinations of Clusters. In this way the problem can partition of the network by using Clusters and/or different
be localized in a specific Cluster or in a single combination of combinations of Clusters. In this way the problem can be localized
Clusters and a more detailed analysis can be performed step-by-step in a specific Cluster or in a single combination of Clusters and a
by successive approximation up to a point-to-point flow detailed more detailed analysis can be performed step-by-step by successive
analysis. approximation up to a point-to-point flow detailed analysis.
This approach can be called Network Zooming and can be performed in This approach can be called Network Zooming and can be performed in
two different ways: two different ways:
1) change the traffic filter and select more detailed flows; 1) change the traffic filter and select more detailed flows;
2) activate new measurement points by defining more specified 2) activate new measurement points by defining more specified
clusters. clusters.
The Network Zooming approach implies that the some filters or rules The Network Zooming approach implies that the some filters or rules
are changed and there is a transient time to wait once the new are changed and there is a transient time to wait once the new
network configuration takes effect and it can be determined by the network configuration takes effect and it can be determined by the
Network Orchestrator/Controller, based on the network conditions. Network Orchestrator/Controller, based on the network conditions.
For example, if the Network Zooming identifies the performance
problem for the traffic coming from a specific source, we need to
recognize the marked signal from this specific source node and its
relative path. For this purpose we can activate all the available
measurement points and specify better the flow filter criteria (i.e.
5-tuple). As an alternative, it can be enough to select packets from
the specific source for delay measurements, and in this case it is
possible to apply the hashing technique as mentioned in the previous
sections.
[I-D.song-opsawg-ifit-framework] defines an architecture where the [I-D.song-opsawg-ifit-framework] defines an architecture where the
centralized Data Collector and Network Management can apply the centralized Data Collector and Network Management can apply the
intelligent and flexible Alternate Marking algorithm as previously intelligent and flexible Alternate Marking algorithm as previously
described. described.
As for RFC 8321 [RFC8321], it is possible to classify the traffic and As for RFC 8321 [RFC8321], it is possible to classify the traffic and
mark a portion of the total traffic. For each period the packet rate mark a portion of the total traffic. For each period the packet rate
and bandwidth are calculated from the number of packets. In this way and bandwidth are calculated from the number of packets. In this way
the Network Orchestrator becomes aware if the traffic rate overcomes the Network Orchestrator becomes aware if the traffic rate overcomes
limits. In addition more precision can be obtained by reducing the limits. In addition more precision can be obtained by reducing the
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o Enterprise SD-WAN: SD-WAN allows to connect remote branch offices o Enterprise SD-WAN: SD-WAN allows to connect remote branch offices
to Data Centers and build higher-performance WANs. A centralized to Data Centers and build higher-performance WANs. A centralized
controller is used to set policies and prioritize traffic. The controller is used to set policies and prioritize traffic. The
SD-WAN takes into account these policies and the availability of SD-WAN takes into account these policies and the availability of
network bandwidth to route traffic. This helps ensure that network bandwidth to route traffic. This helps ensure that
application performance meets service level agreements (SLAs). application performance meets service level agreements (SLAs).
This methodology can also help the path selection for the WAN This methodology can also help the path selection for the WAN
connection based on per Cluster and per flow performance. connection based on per Cluster and per flow performance.
Note that the list is just an example and it is not exhaustive. More
applications are possible.
11. Security Considerations 11. Security Considerations
This document specifies a method to perform measurements that does This document specifies a method to perform measurements that does
not directly affect Internet security nor applications that run on not directly affect Internet security nor applications that run on
the Internet. However, implementation of this method must be mindful the Internet. However, implementation of this method must be mindful
of security and privacy concerns, as explained in RFC 8321 [RFC8321]. of security and privacy concerns, as explained in RFC 8321 [RFC8321].
12. Acknowledgements 12. Acknowledgements
The authors would like to thank Al Morton, Tal Mizrahi, Rachel Huang The authors would like to thank Al Morton, Tal Mizrahi, Rachel Huang
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