SFC Working Group Anil Kumar S N
INTERNET-DRAFT Gaurav Agrawal
Intended Status: Standards Track Vinod Kumar S
Expires: December 30, 2016 Huawei Technologies India
June 28, 2016
Packet Loss Measurement for SFC
draft-agv-sfc-packet-loss-measurement-01
Abstract
This document describes performance measurement(PM) packet loss
measurement for Service Function Chains (SFCs) to assess the
operational status and behavior of a SF, a subset of SFs, a whole SFC
as a function of the actual deterministic SF/SFC. Packet loss
mechanism described in this document is based on [SFC-PM-arch]
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."
This Internet-Draft will expire on December 30, 2016
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Copyright and License 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
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the Trust Legal Provisions and are provided without warranty as
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Terms & Definition . . . . . . . . . . . . . . . . . . . . . 4
1.3 Applicability and Scope . . . . . . . . . . . . . . . . . . 4
2 Massage Format . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Performance Measurement Context Header . . . . . . . . . . . 5
2.2 Packet Loss PM Context Header . . . . . . . . . . . . . . . 6
2.3 Performance Measurement Flow ID . . . . . . . . . . . . . . 8
3 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 Packet Loss Statistics Counter . . . . . . . . . . . . . . . 9
3.2 Initiating a Packet Loss Measurement . . . . . . . . . . . . 9
3.3 Encapsulation of Classified Packets . . . . . . . . . . . . 10
3.4 Incoming Packets Processing at MA . . . . . . . . . . . . . 10
3.5 Outgoing Packets Processing at MA . . . . . . . . . . . . . 11
3.6 MA Reporting the statistics to Collector . . . . . . . . . . 11
3.7 Packet Loss Calculation at Collector . . . . . . . . . . . . 11
4 Security Considerations . . . . . . . . . . . . . . . . . . . . 12
5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 12
5.1 TLV Class . . . . . . . . . . . . . . . . . . . . . . . . . 12
7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1 Normative References . . . . . . . . . . . . . . . . . . . . 13
7.2 Informative References . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1 Introduction
The delivery of end-to-end services often requires various service
functions. These include traditional network service functions such
as firewalls and traditional IP Network Address Translators (NATs),
as well as application-specific functions. The definition and
instantiation of an ordered set of service functions and subsequent
"steering" of traffic through them is termed Service Function
Chaining (SFC).
The common reasons for packet drop are traffic congestion, service
function (DPI/Firewall/Router etc.) performance issue, software
issues (bugs), faulty hardware or cabling and service function
processing errors.
Proper operation of a SFC depends on the ability to monitor and
quickly identify faults and focus attention on the root cause of the
problem. Also service provider service level agreements (SLAs)
depends on the capability to measure and monitor performance metrics
for packet delay. SFC delay measurement is one of the important tool
to achieve above requirements.
Packet loss measurement capability provides operators with greater
visibility into the performance characteristics of their networks,
thereby facilitating planning, troubleshooting, and network
performance evaluation.
This document specifies best possible efficient and accurate
mechanism for packet loss measurement for service function chains
(SFCs) for a SFC network domain.
The packet loss measurement described in this document is realized by
adding a new context header in the network service header.
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1.1 Terminology
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].
1.2 Terms & Definition
Refer to RFC 7665 for definitions of SFC terms.
Measurement Collector: An operational function that collects
measurement data from a measurement agent. Measurement
collector is responsible for collecting the performance
measurement data from measurement agent. Measurement
collector functionality could be integrated with one of
the MA or with the controller itself.
Measurement Agent: An operational function that contains one or
more measurement functions. Measurement agents is
responsible for understand and analyze performance
measurement control information encoded in NSH metadata
and perform the performance data collecting and report the
same to measurement collector with key information to
identify performance measurement instance along with data
collected.
Measurement Controller: An operational function that controls
running, scheduling, and general coordination of measurement
functions by instructing a measurement agent using NSH
metadata. Measurement controller is responsible for
configuring the performance measurement instance.
Optionally performance measurement instance can be
configured manually at the ingress in which case
controller is not required
1.3 Applicability and Scope
This document defines the implementation mechanism for the packet
loss measurement as per performance measurement architecture [SFC-PM-
arch]. This document defines a new NSH message format for carrying
packet loss measurement related control information. It also defines
operations to be carried out for packet loss measurement.
communication mechanism between measurement controller, measurement
collector and MA is out of scope of this document.
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2 Massage Format
2.1 Performance Measurement Context Header
The format of the Performance measurement context headers, is as
described below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class = (IANA PM Class) |C| PM Type |R|R|R| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PM Metadata |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Performance Measurement Context Header
TLV Class: As per [I-D.ietf-sfc-nsh] the TLV class value for
performance measurement needs to be applied from IANA.
PM Type: indicates the type of performance measurement that
needs to be carried out by the MA.
Length: Length of the variable PM metadata, in 4-byte words.
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2.2 Packet Loss PM Context Header
The format of the packet loss PM context headers, is as
described below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class = (IANA PM Class) |C| PM Type |R|R|R| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Window Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MA Identifier1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MA IdentifierN |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Packet Loss PM Context Header
TLV Class: As per [I-D.ietf-sfc-nsh] the TLV class value for
performance measurement needs to be applied from IANA.
PM Type: Indicates the type of performance measurement that needs
to be carried out by the MA. (IANA assigned PM Type PM Loss value)
This memo defines the following values.
0x1 - Packet Loss : indicates PM meta data contains info for
packet loss. Specified SF(s) SHOULD participate in packet loss PM.
0x2 - SF Hop by Hop Packet Loss : indicates PM meta data
contains info for packet loss. All the SF(s) in the SFP SHOULD
participate in the packet loss PM
0x3 - SFF Hop by Hop Packet Loss : indicates PM meta data contains
info for packet loss. All the SFF(s) in the SFP SHOULD participate
in the packet loss PM
0x4 - All Hop by Hop Packet Loss : indicates PM meta data contains
info for packet loss. All the SF(s) and SFF(s)in the SFP SHOULD
participate in the packet loss PM
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0x5 - SFP as a whole : indicates PM meta data contains information
for packet delay. Classifier (source MA) and SF domain boundary SFF
(sink MA) SHOULD participate in the packet delay computation.
Additional values can be added for future PM types and scenarios.
Length: Length of the variable PM metadata, in 4-byte words. It will
have a minimum length of 1 indicating the presence of measurement
window index.
Measurement Window Index: 16 bit number to denote the current
measurement window to which the packet belongs.
Reserved: Reserved 16 bits for future purpose.
Reserved: Reserved 16 bits for future purpose.
MA identifier list: List of participating MA in the SFP.
MA identifier has two parts
1) Node identifier - 24 bit
a) For SFF: MUST be unique number assigned by controller
b) For SF: All zero. Context identifier itself identifies
SF node.
2) Context identifier - 8 bit
a) For SFF: Service index of next SF.
b) For SF: Service index
MA identifier SHOULD be in decreasing order of the SI for
optimized traversal of the SI participation.
The Length of the packet loss PM context headers, is fixed to 1 as
described below, when the PM Type is 2 to 5. Since all SF's in the
SFP has to perform the loss measurement specified in PM type field.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class = (IANA PM Class) |C| Type 2to5 |R|R|R| Len=0x1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Window Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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2.3 Performance Measurement Flow ID
The method of encoding the PMF id is done using the flow id defined
in [I-D.ietf-sfc-nsh].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class = 0x0 |C| Type=0x7 |R|R|R| L=0x1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Performance Measurement Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sample encoding of PMF using flow ID
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Ver|O|C|R|R|R|R|R|R| Length | MD-type=0x2 | Next Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Service Path ID | Service Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class=IANA |C| Type=0x2 |R|R|R| Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Measurement Window Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV Class = 0x0 |C| Type=0x7 |R|R|R| L=0x1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Performance Measurement Flow ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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3 Operations
3.1 Packet Loss Statistics Counter
Every MA needs to maintain the packet loss statistics which they
immediately report it to collector or may accumulate and report to
collector at a reporting interval which depends on local policy.
Below 2 packet statistics counters will be created and maintained at
every MA
1) Rx-STAT[P][M][W]
2) Tx-STAT[P][M][W]
Rx-STAT[P][M][W]: This 2 dimensional statistics counter is maintained
at every MA. Where P stands for PMF ID, M stands for MA identifier
and W stands for window ID. Rx- STAT[P][M][W] counter maintains the
number of packets received for a given PMF ID + MA identifier +
window. PMF ID is unique within a SFC Domain, for a given PMF ID
there could be multiple windows. Rx-STAT[P][M][W] statistics counter
is created when first PM packet for loss measurement is received for
PMF ID + MA identifier + window within a Reporting interval. Rx-
STAT[P][M][W] statistics counter is deleted at expiry of current
reporting interval after Rx-STAT[P][M][W] statistics counters are
reported to collector.
Tx-STAT[P][M][W]: This 2 dimensional statistics counter is maintained
at every MA. Where P stands for PMF ID and W stands for window ID.
Tx- STAT[P][M][W] counter maintains the number of packets sent out
for a given PMF ID + MA identifier + window. PMF ID is unique within
a SFC Domain, for a given PMF ID there could be multiple Windows. Tx-
STAT[P][M][W] statistics counter is created when first PM packet for
loss measurement is sent for PMF ID + MA identifier + window within a
Reporting interval. Rx-STAT[P][M][W] statistics counter is deleted at
expiry of current reporting interval after Tx-STAT[P][M][W]
statistics counters are reported to collector.
3.2 Initiating a Packet Loss Measurement
Measurement Controller programs the PM Instance at the classifier.
Classifier starts the packet classification (based on the
classification rule/policy). The packet classification policy may be
customer/network/service specific. Classifier updates/encodes
corresponding PM instance for classified packets for each PM schedule
in PM context header.
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3.3 Encapsulation of Classified Packets
For the classified packet, PM Context Header is prepared with
following information
- Set the type class value to the IANA allocated PM class.
- Set the type value to the required packet loss measurement type.
- If type value = 0x1
o Encode the list of MA identifier that need to participate in
Packet Loss Measurement.
- If Value = 0x2, 0x3, 0x4, 0x5
o No need to encode MA identifier, since the type dictates the
involved participating MA
- Set the window identifier as the current running window number
- Encode the 32 bit globally unique PMF ID using the flow ID
context header as defined in [I-D quinn-sfc-nsh-tlv].
3.4 Incoming Packets Processing at MA
On receiving the packet with NSH header following operations are
carried out:
Step 1: Detection of PM context header in a packet, by verifying
the PM TLV class as allocated by IANA.
(If not detected, move to step 6)
Step 2: Check if PM type field value is 1 to 5.
(If not move to step 6).
Step 3: If PM type value = 2 to 5 move directly to Step 5
Step 4: Check presence of self MA identifier in MA identifier List.
(If not present, move to step 6)
Step 5: Record the value of PMF ID and window ID; increment the value
of statistics counter Rx-STAT[P][M][W] by 1. If statistics
counter doesn't exist, create it and initialize it with 1.
Step 6: Packet is sent for normal processing
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3.5 Outgoing Packets Processing at MA
At outgoing port of MA following operations are carried out.
Step 1: Record the value of PMF ID and window ID; increment the value
of statistics counter Tx-STAT[P][M][W] by 1. If statistics
counter doesn't exist, create it and initialize it with 1.
Step 2: Packet is sent for normal processing
3.6 MA Reporting the statistics to Collector
Reporting timer will run on Each MA. Consistency of this timer
should be ensured across the entire MA in the SFP, ensuring the
same is out of scope of this document.
On expiry of this timer following information needs to be sent
to the Collector.
- MA identifier
- PM Type Value
- Value of all the accumulated Tx-STAT[P][M][W] statistics
counter along with the corresponding PMF ID and Window Id
- Value of all the accumulated Rx-STAT[P][M][W] statistics counter
along with the corresponding PMF ID and window Id
MA may delete the Tx-STAT[P][M][W], Rx-STAT[P][M][W] after sending
the same to collector.
3.7 Packet Loss Calculation at Collector
Collector accumulates the statistics counters per PMF per MA
identifier per MA per window. On receipt of report from a MA for a
PMF if it has statistics related for an already collected window,
received statistics will be summed up, otherwise a new entry is
created. Collector computes the packet loss using the accumulated
statistics per PMF per MA per window.
Packet Loss between MA (for example from MA1 to MA2) = (MA1)Tx-
STAT[P][M][W] - (MA2)Rx-STAT[P][M][W]
Packet Loss at MA = (MA)Tx-STAT[P][M][W] - (MA)Rx-STAT[P][M][W]
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4 Security Considerations
No specific security considerations for this document
5 IANA Considerations
5.1 TLV Class
IANA is requested to allocate a new class value for performance
measurement from "Network Service Header (NSH) Parameters" registry.
Value Description Reference
----- ----------- ---------
New Performance Measurement [SFC-PM-arch]
6. Acknowledgments
We would like to thank Nobin Mathew for his review and comments.
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7 References
7.1 Normative References
[I-D.ietf-sfc-nsh] Quinn, P. and U. Elzur, "Network Service
Header", draft- ietf-sfc-nsh-01 (work in progress), July
2015.
7.2 Informative References
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784
DOI 10.17487/RFC2784, March 2000,
<http://www.rfc-editor.org/info/rfc2784>.
[RFC5226] Narten, T. and H. Alvestrand,"Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC7498] Quinn, P., Ed. and T. Nadeau,Ed.,"Problem Statement for
Service Function Chaining", RFC 7498, DOI 10.17487/
RFC7498, April 2015,
<http://www.rfc-editor.org/info/rfc7498>.
[SFC-arch]
Quinn, P., Ed. and J. Halpern, Ed., "Service Function
Chaining (SFC) Architecture", 2014,
<http://datatracker.ietf.org/doc/draft-quinn-sfc-arch>.
[SFC-PM-arch]
Anil, Gaurav and Vinod., "Performance Measurement
Architecture for SFC", 2015,
[SFC-PM-Delay]
Anil, Gaurav and Vinod., "Packet Delay Measurement for
SFC", 2015,
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Authors' Addresses
Anil Kumar S N
Huawei Technologies India Pvt. Ltd,
Near EPIP Industrial Area,
Kundalahalli Village,
Whitefield,
Bangalore - 560037
EMail: anil.sn@huawei.com
Gaurav Agrawal
Huawei Technologies India Pvt. Ltd,
Near EPIP Industrial Area,
Kundalahalli Village,
Whitefield,
Bangalore - 560037
EMail: gaurav.agrawal@huawei.com
Vinod Kumar S
Huawei Technologies India Pvt. Ltd,
Near EPIP Industrial Area,
Kundalahalli Village,
Whitefield,
Bangalore - 560037
EMail: vinods.kumar@huawei.com
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