Internet DRAFT - draft-agv-sfc-packet-delay-measurement
draft-agv-sfc-packet-delay-measurement
SFC Working Group
INTERNET-DRAFT Anil Kumar S N
Intended Status: Standards Track Gaurav Agrawal
Vinod Kumar S
Huawei Technologies India
Expires: June 13, 2016 December 11, 2015
Packet Delay Measurement for SFC
draft-agv-sfc-packet-delay-measurement-00
Abstract
Service provider service level agreements (SLAs) depend on the
capability to measure and monitor performance metrics for packet
Delay.
The common reasons for packet delay are Nodal processing(Algorithmic,
Packetization etc...), Queuing, Transmission delay, Propagation delay
and Service Function processing delay.
Packet Delay Measurement capability also 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 passive packet delay measurement for Service Function
Chains (SFCs) for a SFC network domain.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as
Internet-Drafts.
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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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
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Copyright and License Notice
Copyright (c) 2015 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
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Terms & Definition . . . . . . . . . . . . . . . . . . . . . 6
1.3 Applicability and Scope . . . . . . . . . . . . . . . . . . 9
2 Massage Format . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1 Performance Measurement Context Header . . . . . . . . . . . 10
2.2 Packet Delay PM Context Header . . . . . . . . . . . . . . . 10
2.3 Performance Measurement Flow ID . . . . . . . . . . . . . . 12
3 Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Delay Measurement Options . . . . . . . . . . . . . . . . . 13
3.2 Packet Delay Parameters for Option 1 . . . . . . . . . . . . 13
3.3 Packet Delay Parameters for Option 2 . . . . . . . . . . . . 14
3.4 Initiating a Packet Delay Measurement . . . . . . . . . . . 15
3.5 Encapsulation of Classified Packets . . . . . . . . . . . . 15
3.6 Incoming Packets Processing at MA . . . . . . . . . . . . . 16
3.7 Outgoing Packets Processing at MA . . . . . . . . . . . . . 17
3.8 MA Reporting the statistics to Collector . . . . . . . . . . 17
3.9 Packet Delay Calculation at Collector . . . . . . . . . . . 18
3.9.1 Packet Delay Calculation at Collector (Option 1) . . . . 18
3.9.1 Packet Delay Calculation at Collector (Option 2) . . . . 18
4 Security Considerations . . . . . . . . . . . . . . . . . . . . 19
5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 19
5.1 TLV Class . . . . . . . . . . . . . . . . . . . . . . . . . 19
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.1 Normative References . . . . . . . . . . . . . . . . . . . . 20
6.2 Informative References . . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
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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 purpose of this memo is to define a mechanism for packet delay
measurement for Service Function Chains (SFCs)
As mentioned in [SFC-PM-arch] packet delay measurement could be
performed using Active Measurement or Passive Measurement method.
This document describes the Passive Measurement method & active
measurement method is out of scope of this document. The passive
packet delay 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
Network Service: An offering provided by an operator that is
delivered using one or more service functions. This may
also be referred to as a "composite service". The term
"service" is used to denote a "network service" in the
context of this document.
Note: Beyond this document, the term "service" is overloaded
with varying definitions. For example, to some a service is
an offering composed of several elements within the
operator's network, whereas for others a service, or more
specifically a network service, is a discrete element such
as a "firewall". Traditionally, such services (in the latter
sense) host a set of service functions and have a network
locator where the service is hosted.
Classification: Locally instantiated matching of traffic flows
against policy for subsequent application of the required
set of network service functions. The policy may be
customer/network/service specific.
Classifier: An element that performs Classification.
Service Function Chain (SFC): A service function chain defines an
ordered set of abstract service functions and ordering
constraints that must be applied to packets and/or frames
and/or flows selected as a result of classification.
An example of an abstract service function is "a firewall".
The implied order may not be a linear progression as the
architecture allows for SFCs that copy to more than one
branch, and also allows for cases where there is flexibility
in the order in which service functions need to be applied.
The term "service chain" is often used as shorthand for
service function chain.
Service Function (SF): A function that is responsible for specific
treatment of received packets. A Service Function can act
at various layers of a protocol stack (e.g., at the network
layer or other OSI layers). As a logical component, a
service function can be realized as a virtual element or be
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embedded in a physical network element. One or more Service
Functions can be embedded in the same network element.
Multiple occurrences of the service function can exist in
the same administrative domain.
One or more service functions can be involved in the
delivery of added-value services. A non-exhaustive list of
abstract service functions includes: firewalls, WAN and
application acceleration, Deep Packet Inspection (DPI),
Lawful Intercept (LI), server load balancing, NAT44
[RFC3022], NAT64 [RFC6146], NPTv6 [RFC6296], HOST_ID
injection, HTTP Header Enrichment functions, and TCP
optimizer.
An SF may be SFC encapsulation aware (that is, it receives
and acts on information in the SFC encapsulation) or unaware
(in which case, data forwarded to the SF does not contain
the SFC encapsulation). This is often referred to as "SFC
aware" and "SFC unaware", respectively.
Service Function Forwarder (SFF): A service function forwarder
is responsible for forwarding traffic to one or more
connected service functions according to information carried
in the SFC encapsulation, as well as handling traffic coming
back from the SF. Additionally, an SFF is responsible for
delivering traffic to a classifier when needed and supported
, transporting traffic to another SFF (in the same or
different type of overlay), and terminating the Service
Function Path (SFP).
Metadata: Provides the ability to exchange context information
between classifiers and SFs, and among SFs.
Service Function Path (SFP): The service function path is a
constrained specification of where packets assigned to a
certain service function path must go. While it may be so
constrained as to identify the exact locations, it can also
be less specific. The SFP provides a level of indirection
between the fully abstract notion of service chain as a
sequence of abstract service functions to be delivered, and
he fully specified notion of exactly which SFF/SFs the
packet will visit when it actually traverses the network.
By allowing the control components to specify this level of
indirection, the operator may control the degree of SFF/SF
selection authority that is delegated to the network.
SFC Encapsulation: The SFC encapsulation provides, at a minimum,
SFP identification, and is used by the SFC-aware functions,
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such as the SFF and SFC-aware SFs. The SFC encapsulation is
not used for network packet forwarding. In addition to SFP
identification, the SFC encapsulation carries metadata
including data-plane context information.
Rendered Service Path (RSP): Within an SFP, packets themselves
are of course transmitted from and to specific places in the
network, visiting a specific sequence of SFFs and SFs. This
sequence of actual visits by a packet to specific SFFs and
SFs in the network is known as the Rendered Service Path
(RSP). This definition is included here for use by later
documents, such as when solutions may need to discuss the
actual sequence of locations the packets visit.
SFC-Enabled Domain: A network or region of a network that
implements SFC. An SFC-enabled domain is limited to a
single network administrative domain.
SFC Proxy: Removes and inserts SFC encapsulation on behalf of an
SFC-unaware service function. SFC proxies are logical
elements.
Network Node/Element: Device that forwards packets or frames
based on outer header information. In most cases is not
aware of the presence of NSH.
Network Overlay: Logical network built on top of existing
network (the underlay). Packets are encapsulated or
tunneled to create the overlay network topology.
Network Service Header: Data plane header added to frames/
packets. The header contains information required for
service chaining, as well as metadata added and consumed by
network nodes and service elements.
NSH Proxy: Acts as a gateway: removes and inserts SH on behalf
of a service function that is not NSH aware.
Service Classifier: Function that performs classification and
imposes an NSH. Creates a service path. Non-initial (i.e.
subsequent) classification can occur as needed and can alter,
or create a new service path.
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
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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
Base Header: Provides information about service header and payload
protocol
Service Path Header: Provides Path identification and location
within a path
Context Header: Carries opaque metadata and variable length encoded
information
MD Type: Indicates format of NSH beyond Mandatory Base Header and
Service Path Header.
1.3 Applicability and Scope
This document defines the implementation mechanism for the Packet
Delay Measurement as per Performance Measurement Architecture [SFC-
PM-arch]. This document defines a new NSH Message Format for carrying
Packet Delay 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.
2.2 Packet Delay 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-~-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SI(1) | | SI(n) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-~-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 Delay value)
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This memo defines the following values.
0x6 - Packet Delay : indicates PM meta data contains info for
packet Delay. Specified SF(s) SHOULD participate in Packet Delay PM.
0x7 - SF Hop by Hop Packet Delay : indicates PM meta data
contains info for packet Delay. All the SF(s) in the SFP SHOULD
participate in the Packet Delay PM
0x8 - SFF Hop by Hop Packet Delay : indicates PM meta data contains
info for packet Delay. All the SFF(s) in the SFP SHOULD participate
in the Packet Delay PM
0x9 - All Hop by Hop Packet Delay : indicates PM meta data contains
info for packet Delayss. All the SF(s) and SFF(s)in the SFP SHOULD
participate in the Packet Delay PM
0xA - End to End : indicates PM meta data contains info for packet
Delay. Classifier MA and SF domain boundary SFF SHOULD participate
in the Packet Delay PMAdditional 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 mention the 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.
SI: List of participating Service functions in the SFP. It SHOULD be
in decreasing order of the SI for optimized traversal of the SI
participation.
If the number of participating SF is not multiples of
4, then the last word of the PM context header needs to pad 0x0 to
the make it 4 byte aligned.
The Length of the Packet Delay 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 Delay 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
For packet delay measurement all the MA's time should be synchronized
from a centralized stable clock. Among many available time
synchronization protocols all MAs's must use same protocol and
synchronize time to the same centralized stable clock. Selection of
type of time synchronization protocol is for MAs is out of scope of
this document.
Every MA needs to maintain the packet delay statistics which they
immediately report it to collector or may accumulate and report to
collector at a reporting interval which depends on local policy.
3.1 Delay Measurement Options
There are 2 options for packet delay measurement
Option 1: Delay Measurement is performed using single packet in the
Measurement Window.
Option 2: Delay Measurement is performed using multiple packet in a
measurement window.
In case of Option 2 is used for delay measurement, MA sums the
measured time for the received window and reports the summed time
together with the count of samples to the Collector. Collector will
co-relate the time info received across multiple report and compute
the average time for a window.
3.2 Packet Delay Parameters for Option 1
Parameters for Option 1:
1) Rx-Time[P][W]
2) Tx-Time[P][W]
These parameters will be created and maintained at every MA
Rx-Time[P][W]: This 2 dimensional Parameter is maintained at every
MA. In this P stands for PMF ID and W stands for Window ID. It will
contain the system time (NTP UTC time format) when packets is
received for a given PMF ID + Window.
PMF ID is unique within a SFC Domain, for a given PMF ID there could
be multiple Windows. This Parameter is created when a Packet Delay PM
packet is received at a first time within a Reporting interval. The
Parameter is deleted upon expiry of Reporting interval at which it
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will be sent to Collector and deleted from MA.
Tx-Time[P][W]: This 2 dimensional Parameter is maintained at every
MA. In this P stands for PMF ID and W stands for Window ID. It will
contain the system time (NTP UTC time format) when packets is sent
out for a given PMF ID + Window.
PMF ID is unique within a SFC Domain, for a given PMF ID there could
be multiple Windows. This Parameter is created when a Packet Delay PM
packet is sent at a first time within a Reporting interval. The
Parameter is deleted upon expiry of Reporting interval at which it
will be sent to Collector and deleted from MA.
3.3 Packet Delay Parameters for Option 2
Parameter for Option 2:
1) Rx-Sum-Time[P][W]
2) Rx-Sample-Count[P][W]
3) Tx-Sum-Time[P][W]
4) Tx-Sample-Count[P][W]
These parameters will be created and maintained at every MA
Rx-Time[P][W]: This 2 dimensional Parameter is maintained at every
MA. In this P stands for PMF ID and W stands for Window ID. It will
contain the sum of system time when packets are received for a given
PMF ID + Window.
PMF ID is unique within a SFC Domain, for a given PMF ID there could
be multiple Windows. This Parameter is created when a Packet Delay PM
packet is received at a first time within a Reporting interval. The
Parameter is deleted upon expiry of Reporting interval at which it
will be sent to Collector and deleted from MA.
Rx-Sample-Count[P][W]: This 2 dimensional Parameter is maintained at
every MA. In this P stands for PMF ID and W stands for Window ID. It
will contain the count of the PM Delay Sample packets received for a
given PMF ID + Window.
Tx-Time[P][W]: This 2 dimensional Parameter is maintained at very MA.
In this P stands for PMF ID and W stands for Window ID. It will
contain the sum of system time when packets are sent for a given PMF
ID + Window.
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PMF ID is unique within a SFC Domain, for a given PMF ID there could
be multiple Windows. This Parameter is created when a Packet Delay PM
packet is sent at a first time within a Reporting interval. The
Parameter is deleted upon expiry of Reporting interval at which it
will be sent to Collector and deleted from MA.
Tx-Sample-Count[P][W]: This 2 dimensional Parameter is maintained at
every MA. In this P stands for PMF ID and W stands for Window ID. It
will contain the count of the PM Delay Sample packets sent for a
given PMF ID + Window.
3.4 Initiating a Packet Delay Measurement
Measurement Controller Programs the PM Instance at the Classifier.
Within the PM Schedule as programmed in PM Instance, Classifier
starts the packet classification (based on the classification rule
programmed in PM Instance). The packet classification policy may be
customer/network/service specific.
3.5 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 Delay Measurement
type.
- If Type Value = 0x6
o Encode the list of Service Index that need to participate
in Packet Delay Measurement.
- If Value = 0x7, 0x8, 0x9, 0x10
o No need to encode SI, 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].
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3.6 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 6 to 10.
(If not move to step 6).
Step 3: If PM Type Value = 7 to 10 move directly to Step 5
Step 4: Check Presence of self Service index in Service Index List
(If not present, move to step 6)
Step 5: If Option 1 is used then go to Step 5a, if Option 2 is
used then go to Step 5b
Step 5a: Record the value for PMF ID and Window ID; Record
the time when the packet is received Rx-Time[P][W].
Step 5b: Record the value for PMF ID and Window ID; Record
the time when the packet is received and sum it up
in Rx-Sum-Time[P][W]. If Rx-Sum-Time[P][W] doesn't
exist then create it and initialize it with recorded
time value.
Also Increment the value of statistics counter
Rx-Sample-Count[P][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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3.7 Outgoing Packets Processing at MA
At outgoing port of MA following operations are carried out.
Step 1: If Option 1 is used then go to Step 2a, if Option 2 is
used then go to Step 2b
Step 2: If Option 1 is used then go to Step 2a, if Option 2 is
used then go to Step 2b
Step 2a: Record the value for PMF ID and Window ID; Record
the time when the packet is sent Tx-Time[P][W].
Step 2b: Record the value for PMF ID and Window ID; Record
the time when the packet is sent and sum it up in
Tx-Sum-Time[P][W]. If Tx-Sum-Time[P][W] doesn't exist
then create it and initialize it with recorded
time value.
Also Increment the value of statistics counter
Tx-Sample-Count[P][W] by 1. If statistics counter doesn't
exist, create it and initialize it with 1.
Step 3: Packet is sent for Normal Processing
3.8 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.
- Service Index
- PM Type Value
- Value of all the collected Rx-Time[P][W], Rx-Sum-Time[P][W],
& Rx-Sample-Count[P][W] parameters along with the
corresponding PMF ID and Window Id
- Value of all the collected Tx-Time[P][W], Tx-Sum-Time[P][W],
& Tx-Sample-Count[P][W] parameters along with the
corresponding PMF ID and Window Id
MA may delete the parameters after sending the same to collector.
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3.9 Packet Delay Calculation at Collector
Collector accumulates the parameters per PMF per MA per Window.
Collector computes the Packet Delay using the accumulated
parameters per PMF per MA per Window.
3.9.1 Packet Delay Calculation at Collector (Option 1)
Packet Delay between MA (for example from MA1 to MA2)
= (MA2)Rx-Time[P][W] - (MA1)Tx-Time[P][W]
Packet Delay at MA = (MA)Tx-Time[P][W] - (MA)Rx-Time[P][W]
3.9.1 Packet Delay Calculation at Collector (Option 2)
On receipt of report from a MA Collector performs following operation
1) For a PMF if it has Rx-Sum-Time[P][W]/Tx-Sum-Time[P][W] related
for an already collected window, received value will be summed up
with an existing one, otherwise a new entry is created.
2) For a PMF if it has Rx-Sample-Count[P][W]/Tx-Sample-Count[P][W]
related for an already collected window, received value will be
summed up with an existing one, otherwise a new entry is created.
3) Average Time computation by Collector for every MA
Average-Rx-Time[P][W] = Rx-Sum-Time[P][W]/Rx-Sample-Count[P][W]
Average-Tx-Time[P][W] = Tx-Sum-Time[P][W]/Tx-Sample-Count[P][W]
4) Packet Delay between MA (for example from MA1 to MA2)
= (MA2)Average-Rx-Time[P][W] - (MA1)Average-Tx-Time[P][W]
Packet Delay at MA
= (MA)Average-Tx-Time[P][W] - (MA)Average-Rx-Time[P][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]
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6 References
6.1 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.
[RFC1305] Mills, D., "Network Time Protocol (Version 3)
Specification, Implementation and Analysis",
RFC 1305, March 1992.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, June 2010.
6.2 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,
<TODO>
[SFC-PM-Loss]
Anil, Gaurav and Vinod., "Packet Loss Measurement for
SFC", 2015,
<TODO>
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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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