Internet DRAFT - draft-fioccola-ippm-rfc6812-alt-mark-ext
draft-fioccola-ippm-rfc6812-alt-mark-ext
Network Working Group G. Fioccola
Internet-Draft Telecom Italia
Intended status: Informational A. Clemm
Expires: September 22, 2016 Cisco Systems
M. Cociglio
Telecom Italia
M. Chandramouli
Cisco Systems
A. Capello
Telecom Italia
March 21, 2016
Alternate Marking Extension to Cisco SLA Protocol RFC6812
draft-fioccola-ippm-rfc6812-alt-mark-ext-01
Abstract
Cisco's Service-Level Assurance Protocol (Cisco's SLA Protocol) RFC
6812 [RFC6812] is a Performance Measurement protocol that has been
widely deployed. The protocol is used to measure service-level
parameters such as network latency, delay variation, and packet/frame
loss. This document describes an extension to the Cisco SLA Protocol
Measurement-Type UDP-Measurement, in order to implement alternate
marking methodology detailed in [I-D.tempia-ippm-p3m]. The extension
is used to measure service level parameters by marking test traffic.
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 http://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."
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This Internet-Draft will expire on September 22, 2016.
Copyright Notice
Copyright (c) 2016 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
(http://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
to this document. Code Components extracted from this document must
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. Description of the method . . . . . . . . . . . . . . . . . . 3
2.1. Packet loss measurement . . . . . . . . . . . . . . . . . 4
2.2. Delay measurement . . . . . . . . . . . . . . . . . . . . 4
2.3. Delay variation measurement . . . . . . . . . . . . . . . 6
3. Hybrid measurement . . . . . . . . . . . . . . . . . . . . . 6
4. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Control Phase . . . . . . . . . . . . . . . . . . . . . . 8
4.1.1. Control Request . . . . . . . . . . . . . . . . . . . 9
4.1.1.1. Command Header . . . . . . . . . . . . . . . . . 9
4.1.1.2. CSLDs . . . . . . . . . . . . . . . . . . . . . . 9
4.1.2. Control Response Message . . . . . . . . . . . . . . 13
4.2. Measurement Phase . . . . . . . . . . . . . . . . . . . . 13
4.3. Calculation Phase . . . . . . . . . . . . . . . . . . . . 15
5. Implementation notes . . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
8. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 15
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. Normative References . . . . . . . . . . . . . . . . . . 17
10.2. Informative References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
Cisco SLA Protocol involves a system sending synthetic test traffic,
which is reflected by a responder back to the sender. In the course,
both sender and responder add a set of time stamps to the packet.
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The packet is first time stamped when it is sent. A second time
stamp is added by responder when it is received, and third time stamp
when packet is sent back. A fourth time stamp is added when the
sender receives the reflected packet. Based on time stamps and other
information, the sender computes performance metrics such as loss,
delay, and jitter.
One technique for passive performance measurements is described in
[I-D.tempia-ippm-p3m]. This technique involves marking production
flows as they traverse the network, then analyzing flow data
associated with those marked flows. Passive measurements are very
accurate in that they measure actual production traffic. However,
there are scenarios in which passive measurements are not an option.
For example, there may be no suitable flows currently occurring
between pairs of nodes to be measured, or traffic may be tunneled and
not be accessible to marking. In such cases, active measurements
using synthetic test traffic need to be considered.
This document specifies an extension to Cisco SLA Protocol which
allows to use Cisco SLA Protocol to generate synthetic traffic, but
allows subjecting test traffic to the same techniqe described in
[I-D.tempia-ippm-p3m]. Instead of time stamping test traffic, test
traffic is marked and measurements occur by analyzing resulting flow
data.
2. Description of the method
In order to perform packet loss, delay and jitter measurements on a
traffic flow, different approaches exist. The method proposed
consists in counting and timestamping the packets sent from one end,
the packets received on the other end, and compare the two values.
Therefore the devices performing the measurement have to refer
exactly to the same set of packets. So the flow is virtually spit in
consecutive blocks by coloring the packets so that the packets
belonging to the same block will have the same color, whilst
consecutive blocks will have different colors. Each change of color
represents a sort of auto-synchronization signal that guarantees the
consistency of measurements taken by different devices along the
path.
This approach, called Alternate Marking method, is efficient both for
passive performance monitoring and for active performance monitoring.
In this document we describe the implementation for Active
Measurement.
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+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| | | |
| Sender | | Responder |
| |===============================>| |
| |<===============================| |
+-+-+-+-+-+-+-+ Traffic flow +-+-+-+-+-+-+-+
. .
. .
<------------------------------>
End-to-End Packet loss, Delay and Jitter
Figure 1: Available measurements
Previous Figure represents two end points (Sender and Responder) that
exchange two equal data flows in both direction. The data flows
start and end together. Packets are colored and the color changes
every marking interval. The method can be used to measure packet
loss, delay and jitter.
2.1. Packet loss measurement
The basic idea is to virtually split traffic flows into consecutive
blocks: each block represents a measurable entity unambiguously
recognizable by all network devices along the path. By counting the
number of packets in each block and comparing the values measured by
Sender and Responder, it is possible to measure packet loss occurred
in any single block between the two end points.
A simple way to create the blocks is to "color" the traffic (two
colors are sufficient) so that packets belonging to different
consecutive blocks will have different colors. Whenever the color
changes, the previous block terminates and the new one begins. The
number of packets in each block depends on the criterion used to
create the blocks: if the color is switched after a fixed number of
packets, then each block will contain the same number of packets
(except for any losses); but if the color is switched according to a
fixed timer, then the number of packets may be different in each
block depending on the packet rate.
2.2. Delay measurement
The same principle used to measure packet loss can be applied also to
one-way delay measurement. There are two alternatives, shown below:
o Delay for each packet: For active measurement two alternate
marking data flows are generated in both direction, so the
alternation of colors can be used as a time reference to calculate
the delay. Whenever the color changes (that means that a new
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block has started) an end point can store the timestamps of all
packets of the new block. The timestamps can be compared with the
timestamps of the same packets on the other end point to compute
packet delay. This method for measuring the delay is sensitive to
out of order reception of packets. In order to overcome this
problem between packets there should be a security time gap to
avoid out of order issues. If the packet rate exchanged between
the two end points is adequate each end points can store all the
timestamp of the block and the packet delay can be computed for
all the packets of the block, included minimum, maximum, average
and median delay values.
o Average delay: A different approach, based on the concept of
average delay, can be take in account for active measurement. The
average delay is calculated by considering the average arrival
time of the packets within a single block. The network device
locally stores a timestamp for each packet received within a
single block: summing all the timestamps and dividing by the total
number of packets received, the average arrival time for that
block of packets can be calculated. By subtracting the average
arrival times of the two end points it is possible to calculate
the average delay. This method is robust to out of order packets
and also to packet loss (only a small error is introduced).
Moreover, it greatly reduces the number of timestamps (only one
per block for each end point) that have to be collected and
transmitted for the calculation. On the other hand, it only gives
one measure for the duration of the block, and it doesn't give the
minimum, maximum and median delay values. RFC 6703 [RFC6703]
recommends to report both median and average delay in order to
obtain additional information about the distribution. But the
same procedure of the average delay is not applicable to median
delay because the median is not a linear operator. So the average
delay could be considered as a light measurement because the
calculation is achieved by exchanging only the average timestamp
for each colored block (without exchanging all the timestamps).
For this reason the average delay is not the main technique, but a
secondary option in case we have to save computational resources.
By summing the one-way delay measurements of the two directions of a
path, it is also possible to measure the two-way delay (round-trip
delay).
In brief, there are three choices to compute delay for active
measurement:
o The two end points could store all packets timestamps in both
directions. At the end of the period all timestamps are
exchanged. In this way, delay is calculated for each packet.
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o The two end points calculate only the average timestamp that is
exchanged at the end of the period. In this way only the average
delay is calculated.
o The two end points sent packets with a specified and shared
traffic profile and each end point could make its own calculation
(data are not exchanged so it is not so accurate, but it depends
on hardware and software capabilities).
Note: How data and timestamps are exchanged is outside the scope of
this document.
2.3. Delay variation measurement
Similarly to one-way delay measurement, the method can also be used
to measure the inter-arrival jitter. The alternation of colors can
be used as a time reference to measure delay variations. The inter-
arrival jitter can be easily derived from one-way delay measurement,
by evaluating the delay variation of consecutive samples.
The concept of average delay can also be applied to delay variation,
by evaluating the variation of average interval between consecutive
packets of the flow.
3. Hybrid measurement
In order to have both end to end measurements and intermediate
measurements (hybrid measurements) Sender and Responder exchanges
traffic flows and apply alternate marking over these flows. In the
intermediate points artificial traffic is managed in the same way as
real traffic and measured as specified before.
4. Protocol
The Alternate Marking extension to Cisco Service Level Assurance
Protocol consists of three distinct phases, Control Phase,
Measurement Phase and Calculation Phase.
The Control Phase is the first phase of message exchanges and forms
the base protocol. This phase establishes the identity of the Sender
and provides information for the Measurement Phase. A single message
pair of Control Request and Control Response marks this phase. The
Sender initiates a Control Request message that is acknowledged by
the Responder with a Control Response message. The Control Request
may be sent multiple times if a Control Response has not been
received; the number of times the message is retried is configurable
on the Sender element.
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The Measurement Phase forms the second phase and is comprised of an
exchange of two equal alternate marking data flows between Sender and
Responder. Sender and Responder generate test traffic and apply
marking, not traffic is reflected and no timestamping is added to
packets.
The Calculation Phase is introduced "ad hoc" for Alternate Marking
implementation because it does not exist in Cisco Service Level
Assurance Protocol described in RFC 6812 [RFC6812]. After test
execution there are some alternatives to compute packet loss, delay
and delay variation:
o Local assessment: Sender initiates a Calculation Request message
and Responder sends back a Calculation Response message. Sender
and Responder, upon receipt test traffic, create data structure
with timestamped records then computes service level metrics from
that data structure. Let's call this data structure the test
receipt.
o Central assessment: A "central" entity (e.g. a controller)
compares the test receipt collected by the Responder with data
structure obtained from the Sender, then computes the service
levels by means of comparing.
o Local assessment with reference recording: Both sender and
receiver play out the same test traffic. Assessment is done
locally not by computing metrics over the test receipt, but by
"overlaying" the original with the one that was received and
computing the delta.
The number and frequency with which messages are sent SHOULD be
controlled by configuration on the Sender element, along with the
waiting time for a Control Response.
The following sequence diagram depicts the message exchanges:
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+-+-+-+-+-+-+-+ Control Request +-+-+-+-+-+-+-+
| | | |
| Sender | | Responder |
| | | |
| | | |
+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+
| |
| Control Request |
| -------------------------------------------->|
| |
| Control Response |
|<---------------------------------------------|
| |
| |
| Measurement Phase |
|<============================================>|
| |
| |
| Calculation Phase |
|<-------------------------------------------->|
| |
To utilize Cisco SLA Protocol, some extensions are needed. As part
of the Control Request, the Sender needs to indicate that it will
send test traffic to be analyzed. However, it indicates that
alternate marking techniques are to be used and that traffic is going
to be marked. Likewise, it can indicate to the Responder to not
simply reflect the marked traffic, but to generate a separate stream
of marked test traffic back to the sender. The marking pattern will
be conveyed (including the alternate markings to be used and duration
of the marking intervals). The implementation of measurements
involves analyzing the marked traffic as needed. Conveying of
results of the analysis of observed traffic occurs through separate
means, not specified here.
4.1. Control Phase
The Control Phase, as described in RFC 6812 [RFC6812] section 3.1,
begins with the Sender sending a Control-Request message to the
Responder. The Responder replies by sending a Control-Response with
an appropriate Status indicating Success when the Sender identity is
verified and the requested UDP port was successfully opened. In all
other cases, a non-zero Status is returned in the Command-Header
Status field.
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4.1.1. Control Request
The Control Request message, as described in RFC 6812 [RFC6812]
section 3.1.1, consists of a Command Header followed by one or more
Command, Status, Length and Data sections (henceforth known as CSLD).
At the minimum, there SHOULD be at the least two CSLD sections, one
of which is the authentication CSLD section and the other carries
information for the Measurement Phase simulation type.
4.1.1.1. Command Header
The Command Header is the first section of the Control Request
message and is described in RFC 6812 [RFC6812] section 3.1.1.1.
4.1.1.2. CSLDs
The two CSLDs to be included, in order, along with the Command Header
are:
o The Authentication CSLD
o A Measurement Type CSLD
In this revision of the protocol, an additional Measurement Type CSLD
has been defined, the Alternate Marking Measurement Type CSLD. In
RFC 6812 [RFC6812] section 3.1.1.2 is described the UDP-Measurement
CSLD.
4.1.1.2.1. Authentication CSLD
The Authentication CSLD provides the message authentication and
verifies the requester knows the shared-secret. The format for the
Authentication CSLD is detailed in RFC 6812 [RFC6812] section
3.1.1.2.1.
4.1.1.2.2. Alternate Marking Measurement CSLD
The Alternate Marking Measurement CSLD indicates the Measurement Type
to be used during the Measurement Phase and specifies the addresses
and UDP port to be opened as well as the duration the port has to be
kept open for the measurement phase. The format of the CSLD is as
follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Command | Status |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Command length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Type | Role | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Session Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| Control Source Address |
+ +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ +
| Control Destination Address |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ +
| Measurement Source Address |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ +
| Measurement Destination Address |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Control Source Port | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Source Port | Measurement Destination Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Starting Time |
+ +
| |
+ +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic profile | Traffic ToS |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Marking mode |Assessment mode| Marking Period |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The new fields that have been added to RFC 6812 [RFC6812] section
3.1.1.2.2 are: Measurement Starting time, Traffic Profile, Traffic
TOS, Marking mode, Assesment mode, Marking period. They are
described below.
The unchanged fields are detailed in RFC 6812 [RFC6812] section
3.1.1.2.2:
So the new fields in the Alternate Marking Measurement CSLD have the
following meaning:
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+-------------+-----------+-----------------------------------------+
| Field | Size | Definition |
| | (bits) | |
+-------------+-----------+-----------------------------------------+
| Command | 16 | Indicates that the CSLD is to simulate |
| | | UDP alternate marking traffic |
| | | measurements. |
| --------- | --------- | -------------------------- |
| Measurement | 64 | Carries the timestamp when the |
| Starting | | Measurement Phase will start |
| Time | | |
| --------- | --------- | -------------------------- |
| Traffic | 16 | Indicates a fixed profile with an |
| Profile | | assigned value (defined outside this |
| | | document), to establish size, number of |
| | | packets, milliseconds between packets |
| | | that are generated in both directions. |
| --------- | --------- | -------------------------- |
| Traffic ToS | 16 | Indicates the Type of Service of the |
| | | generated test frames: but if the |
| | | marking field is the ToS field, the two |
| | | marking ToS values are the first and |
| | | the last 8 bits; otherwise if the |
| | | marking field is different, the first 8 |
| | | bits are zero and the last 8 bits |
| | | indicates the ToS of all the generated |
| | | frames. |
| --------- | --------- | -------------------------- |
| Marking | 8 | Indicates one of the alternatives for |
| mode | | Marking Field: marking IPv4 header |
| | | (Type of Service Field or the last |
| | | reserved bit of the Flag field) or |
| | | marking UDP payload (Measurement Type |
| | | or Data). |
| --------- | --------- | -------------------------- |
| Assessment | 8 | Indicates one of the three alternatives |
| mode | | for the Calculation Phase: 1 - Local |
| | | assessment, 2 - Central assessment, 3 - |
| | | Local assessment with reference |
| | | recording. |
| --------- | --------- | -------------------------- |
| Marking | 16 | Indicates the duration in seconds of |
| Period | | the Alternate Marking period |
+-------------+-----------+-----------------------------------------+
Note: The source addresses are only indicative of identity of the
originator and cannot be used as destination for responses in a NAT
environment.
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Note: In case of Local assessment with reference recording, Sender
and Responder exchanges the refernce reconding before the Measurement
Phase.
Note: All timestamps have the format as described in RFC 5905
[RFC5905] and is as follows: the first 32 bits represent the unsigned
integer number of seconds elapsed since 0h on 1 January 1900; the
next 32 bits represent the fractional part of a second thereof. The
timestamp definition is also similar to RFC 4656 [RFC4656]
In addition, the timestamp format used can be as described for the
low-order 64 bits of the IEEE 1588-2008 (1588v2) Precision Time
Protocol timestamp format [IEEE1588]. This truncated format consists
of a 32-bit seconds field followed by a 32-bit nanoseconds field, and
is the same as the IEEE 1588v1 timestamp format. This timestamp
definition is similar to the default timestamp as specified in RFC
6374 [RFC6374]
Implementations MUST use only one of the two formats. The chosen
format is negotiated out-of-band between the endpoints.
4.1.2. Control Response Message
In response to the Control Request Message the network element
designated the Responder sends back a Control Response Message that
reflects the Command Header with an updated Status field and includes
the two CSLD sections that also carry updated Status fields. Hence,
the format is identical to the Control Request message as described
above. The supported values of the Status fields are the same
described in RFC 6812 [RFC6812] section 3.1.2.
4.2. Measurement Phase
Upon receiving the Control Response message with the Status set to
Success, the second phase of the protocol, the Measurement Phase, is
initiated. In all other cases when the Status is not success no
measurement traffic is initiated. In the Measurement Phase the
Sender sends a stream of measurement messages. The measurement
message stream consists of packets/frames that are spaced a
configured number of milliseconds.
The Measurement messages as defined by this document for Alternate
Marking UDP Measurements is as shown below and is simplified in
comparison to RFC 6812 [RFC6812] section 3.2. In particular the
fields that have been removed from RFC 6812 [RFC6812] section 3.2
are: Sender Send Time, Responder Receive Time, Responder Send Time,
Sender Receive Time, Sender Clock Offset, Responder Clock Offset,
Sender Sequence No. and Responder Sequence No.
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The format of the Measurement messages is the same for the exchange
in both directions, that is when sent from the Sender to the
Responder and from the Responder to the Sender.
Note: Marking field can be chosen in two ways: marking UDP payload or
marking IPv4 header. Marking IPv4 header (Type of Service Field or
the last reserved bit of the Flag field) is useful so in this way the
active measurement could use the same functions of passive
measurement.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Data .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The fields for the UDP Measurement message have the following
meaning:
+-------------+-----------+-----------------------------------------+
| Field | Size | Description |
| | (bits) | |
+-------------+-----------+-----------------------------------------+
| Measurement | 16 | Carries the type of measurement being |
| Type | | performed (This field can include |
| | | Marking: at least two values); 1 - |
| | | Reserved, 2 - Reserved, 3 - UDP |
| --------- | --------- | -------------------------- |
| Reserved | 16 | Reserved field and MUST be set to 0 |
| --------- | --------- | -------------------------- |
| Data | 32 bit | This field is used to pad up to the |
| | aligned | configured request data size. The |
| | | minimum requested data size SHOULD be |
| | | 512 bytes and this field will be of |
| | | length 512 minus the length of the |
| | | previous fields. This field can include |
| | | Marking |
+-------------+-----------+-----------------------------------------+
Note: No timestamp, No sequence number. The two data flows are
indipendent.
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4.3. Calculation Phase
As mentioned above, the Calculation Phase is introduced "ad hoc" for
Alternate Marking implementation because it does not exist in Cisco
Service Level Assurance Protocol described in RFC 6812 [RFC6812].
After test execution there are some alternatives to compute packet
loss, delay and delay variation:
o Local assessment: Sender initiates a Calculation Request message
and Responder sends back a Calculation Response message. Sender
and Responder, upon receipt test traffic, create data structure
with timestamped records then computes service level metrics from
that data structure. Let's call this data structure the test
receipt).
o Central assessment: A "central" entity (e.g. a controller)
compares the test receipt collected by the Responder with data
structure obtained from the Sender, then computes the service
levels by means of comparing.
o Local assessment with reference recording: Both sender and
receiver play out the same test traffic. Assessment is done
locally not by computing metrics over the test receipt, but by
"overlaying" the original with the one that was received and
computing the delta.
5. Implementation notes
Implementation notes are detailed in RFC 6812 [RFC6812] section 4.
6. IANA Considerations
IANA needs to reserve a new value for Alternate Marking CSLD Command
Registry. The available values for future extensions are detailed in
RFC 6812 [RFC6812] section 6.
7. Security Considerations
Security Considerations are detailed in RFC 6812 [RFC6812] section 7.
8. Terminology
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+-------------+-----------------------------------------------------+
| Term | Description |
+-------------+-----------------------------------------------------+
| Control | A phase during which Control Request and Control |
| Phase | Response is exchanged. |
| --------- | -------------------------- |
| L2 | OSI Data Link Layer |
| --------- | -------------------------- |
| L3 | OSI Network Layer |
| --------- | -------------------------- |
| Measurement | Active measurement phase that is marked by a |
| Phase | sequence of Measurement Request and Measurement |
| | Response exchanges. |
| --------- | -------------------------- |
| Metric | A particular characteristic of the network data |
| | traffic, for example latency, jitter, packet/frame |
| | loss |
| --------- | -------------------------- |
| Responder | A network element that responds to a message |
| --------- | -------------------------- |
| RTP | Real-time Transport Protocol |
| --------- | -------------------------- |
| Sender | A network element that is the initiator of a |
| | message exchange |
| --------- | -------------------------- |
| Service | This is the level of service that is agreed upon |
| Level | between the Provider and the Customer |
| --------- | -------------------------- |
| UDP | User Datagram Protocol |
+-------------+-----------------------------------------------------+
9. Acknowledgements
Thanks to Luca Castaldelli, Francesco Burgio and Stefano Righetti
from Telecom Italia for their contribution to the prototype
implementation of the method.
Mauro Cociglio and Giuseppe Fioccola worked in part on the Leone
research project, which received funding from the European Union
Seventh Framework Programme [FP7/2007-2013] under grant agreement
number 317647.
10. References
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10.1. Normative References
[I-D.tempia-ippm-p3m]
Capello, A., Cociglio, M., Fioccola, G., Castaldelli, L.,
and A. Bonda, "A packet based method for passive
performance monitoring", draft-tempia-ippm-p3m-02 (work in
progress), October 2015.
[IEEE1588]
IEEE, "1588-2008 Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems", March 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6812] Chiba, M., Clemm, A., Medley, S., Salowey, J., Thombare,
S., and E. Yedavalli, "Cisco Service-Level Assurance
Protocol", RFC 6812, DOI 10.17487/RFC6812, January 2013,
<http://www.rfc-editor.org/info/rfc6812>.
10.2. Informative References
[RFC3579] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication
Dial In User Service) Support For Extensible
Authentication Protocol (EAP)", RFC 3579,
DOI 10.17487/RFC3579, September 2003,
<http://www.rfc-editor.org/info/rfc3579>.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<http://www.rfc-editor.org/info/rfc4656>.
[RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
384, and HMAC-SHA-512 with IPsec", RFC 4868,
DOI 10.17487/RFC4868, May 2007,
<http://www.rfc-editor.org/info/rfc4868>.
[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<http://www.rfc-editor.org/info/rfc5357>.
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[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<http://www.rfc-editor.org/info/rfc5905>.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374,
DOI 10.17487/RFC6374, September 2011,
<http://www.rfc-editor.org/info/rfc6374>.
[RFC6703] Morton, A., Ramachandran, G., and G. Maguluri, "Reporting
IP Network Performance Metrics: Different Points of View",
RFC 6703, DOI 10.17487/RFC6703, August 2012,
<http://www.rfc-editor.org/info/rfc6703>.
Authors' Addresses
Giuseppe Fioccola
Telecom Italia
Via Reiss Romoli, 274
Torino 10148
Italy
Email: giuseppe.fioccola@telecomitalia.it
Alexander Clemm
Cisco Systems
170 West Tasman Drive
San Jose 95134
USA
Phone: 1-408-526-4000
Email: alex@cisco.com
Mauro Cociglio
Telecom Italia
Via Reiss Romoli, 274
Torino 10148
Italy
Email: mauro.cociglio@telecomitalia.it
Fioccola, et al. Expires September 22, 2016 [Page 18]
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Mouli Chandramouli
Cisco Systems
Email: moulchan@cisco.com
Alessandro Capello
Telecom Italia
Via Reiss Romoli, 274
Torino 10148
Italy
Email: alessandro.capello@telecomitalia.it
Fioccola, et al. Expires September 22, 2016 [Page 19]
