Network Working Group W. Sun, Ed.
Internet-Draft SJTU
Intended status: Standards Track G. Zhang, Ed.
Expires: February 2, 2010 CATR
August 26, 2009
Label Switched Path (LSP) Dynamic Provisioning Performance Metrics in
Generalized MPLS Networks
draft-ietf-ccamp-lsp-dppm-07.txt
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. This document may contain material
from IETF Documents or IETF Contributions published or made publicly
available before November 10, 2008. The person(s) controlling the
copyright in some of this material may not have granted the IETF
Trust the right to allow modifications of such material outside the
IETF Standards Process. Without obtaining an adequate license from
the person(s) controlling the copyright in such materials, this
document may not be modified outside the IETF Standards Process, and
derivative works of it may not be created outside the IETF Standards
Process, except to format it for publication as an RFC or to
translate it into languages other than English.
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.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on February 27, 2010.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
Sun & Zhang Expires February 27, 2010 [Page 1]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Sun & Zhang Expires February 27, 2010 [Page 2]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
Abstract
Generalized Multi-Protocol Label Switching (GMPLS) is one of the most
promising candidate technologies for future data transmission
network. GMPLS has been developed to control and operate different
kinds of network elements, such as conventional routers, switches,
Dense Wavelength Division Multiplexing (DWDM) systems, Add- Drop
Multiplexers (ADMs), photonic cross-connects (PXCs), optical cross-
connects (OXCs), etc. Dynamic provisioning ability of these
physically diverse devices differs from each other drastically. At
the same time, the need for dynamically provisioned connections is
increasing because optical networks are being deployed in metro
areas. As different applications have varied requirements in the
provisioning performance of optical networks, it is imperative to
define standardized metrics and procedures such that the performance
of networks and application needs can be mapped to each other.
This document provides a series of performance metrics to evaluate
the dynamic LSP provisioning performance in GMPLS networks,
specifically the dynamic LSP setup/release performance. These
metrics can depict the features of GMPLS networks in LSP dynamic
provisioning.
Sun & Zhang Expires February 27, 2010 [Page 3]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 7
2. Conventions Used in This Document . . . . . . . . . . . . . . 8
3. Overview of Performance Metrics . . . . . . . . . . . . . . . 9
4. A Singleton Definition for Single Uni-directional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 10
4.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 11
4.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 11
4.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 11
4.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 12
5. A Singleton Definition for multiple Uni-directional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 13
5.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 13
5.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 13
5.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 13
5.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 14
5.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 15
6. A Singleton Definition for Single Bi-directional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 16
6.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 17
6.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 17
6.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 17
6.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 17
6.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 18
7. A Singleton Definition for multiple Bi-directional LSPs
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 19
7.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 19
7.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 19
7.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 19
7.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 19
7.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 20
7.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 21
Sun & Zhang Expires February 27, 2010 [Page 4]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
8. A Singleton Definition for LSP Graceful Release Delay . . . . 22
8.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 22
8.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 22
8.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 22
8.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 22
8.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 22
8.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 23
8.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 24
9. A Definition for Samples of Single Uni-directional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 26
9.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 26
9.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 26
9.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 26
9.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 27
9.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 27
9.7. Typical testing cases . . . . . . . . . . . . . . . . . . 27
9.7.1. With no LSP in the Network . . . . . . . . . . . . . . 28
9.7.2. With a number of LSPs in the Network . . . . . . . . . 28
10. A Definition for Samples of Multiple Uni-directional LSPs
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 29
10.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 29
10.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 29
10.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 29
10.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 29
10.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 30
10.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 30
10.7. Typical testing cases . . . . . . . . . . . . . . . . . . 30
10.7.1. With No LSP in the Network . . . . . . . . . . . . . . 31
10.7.2. With a Number of LSPs in the Network . . . . . . . . . 31
11. A Definition for Samples of Single Bi-directional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 32
11.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 32
11.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 32
11.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 32
11.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 32
11.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 33
11.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 33
11.7. Typical testing cases . . . . . . . . . . . . . . . . . . 34
11.7.1. With No LSP in the Network . . . . . . . . . . . . . . 34
11.7.2. With a Number of LSPs in the Network . . . . . . . . . 34
12. A Definition for Samples of Multiple Bi-directional LSPs
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 35
12.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 35
Sun & Zhang Expires February 27, 2010 [Page 5]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
12.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 35
12.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 35
12.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 35
12.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 36
12.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 36
12.7. Typical testing cases . . . . . . . . . . . . . . . . . . 36
12.7.1. With No LSP in the Network . . . . . . . . . . . . . . 37
12.7.2. With a Number of LSPs in the Network . . . . . . . . . 37
13. A Definition for Samples of LSP Graceful Release Delay . . . . 38
13.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 38
13.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 38
13.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 38
13.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 38
13.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 38
13.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 39
14. Some Statistics Definitions for Metrics to Report . . . . . . 40
14.1. The Minimum of Metric . . . . . . . . . . . . . . . . . . 40
14.2. The Median of Metric . . . . . . . . . . . . . . . . . . . 40
14.3. The percentile of Metric . . . . . . . . . . . . . . . . . 40
14.4. Failure statistics of Metric . . . . . . . . . . . . . . . 40
14.4.1. Failure Count . . . . . . . . . . . . . . . . . . . . 41
14.4.2. Failure Ratio . . . . . . . . . . . . . . . . . . . . 41
15. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 42
16. Security Considerations . . . . . . . . . . . . . . . . . . . 43
17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44
18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 45
19. References . . . . . . . . . . . . . . . . . . . . . . . . . . 46
19.1. Normative References . . . . . . . . . . . . . . . . . . . 46
19.2. Informative References . . . . . . . . . . . . . . . . . . 46
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 48
Sun & Zhang Expires February 27, 2010 [Page 6]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) is one of the most
promising control plane solutions for future transport and service
network. GMPLS has been developed to control and operate different
kinds of network elements, such as conventional routers, switches,
Dense Wavelength Division Multiplexing (DWDM) systems, Add-Drop
Multiplexors (ADMs), photonic cross-connects (PXCs), optical cross-
connects (OXCs), etc. Dynamic provisioning ability of these
physically diverse devices differs from each other drastically.
The introduction of a control plane into optical circuit switching
networks provides the basis for automating the provisioning of
connections and drastically reduces connection provision delay. As
more and more services and applications are seeking to use GMPLS
controlled networks as their underlying transport network, and
increasingly in a dynamic way, the need is growing for measuring and
characterizing the performance of LSP provisioning in GMPLS networks,
such that requirement from applications and the provisioning
capability of the network can be mapped to each other.
This draft defines performance metrics and methodologies that can be
used to depict the dynamic LSP provisioning performance of GMPLS
networks, more specifically, performance of the signaling protocol.
The metrics defined in this document can be used to depict the
average performance of GMPLS implementations.
Sun & Zhang Expires February 27, 2010 [Page 7]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
2. Conventions Used in This Document
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 [RFC2119].
Sun & Zhang Expires February 27, 2010 [Page 8]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
3. Overview of Performance Metrics
In this memo, to depict the dynamic LSP provisioning performance of a
GMPLS network, we define 3 performance metrics: uni-directional LSP
setup delay, bi-directional LSP setup delay, and LSP graceful release
delay. The latency of the LSP setup/release signal is conceptually
similar to the Round-trip Delay in IP networks. This enables us to
refer to the structures and notions introduced and discussed in the
IPPM Framework document, [RFC2330] [RFC2679] [RFC2681]. The reader
is assumed to be familiar with the notions in those documents.
Note that data path related metrics, for example, the time between
the reception of RESV message by ingress node and forward data path
becomes operational, are defined in another document
[I-D.sun-ccamp-dpm]. An implementation MAY choose whether to
implement metrics in the two documents together. However, it is
RECOMMENDED that both measurements are performed to complement each
other.
Sun & Zhang Expires February 27, 2010 [Page 9]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
4. A Singleton Definition for Single Uni-directional LSP Setup Delay
This part defines a metric for single uni-directional Label Switched
Path setup delay across a GMPLS network.
4.1. Motivation
Single uni-directional Label Switched Path setup delay is useful for
several reasons:
o Single LSP setup delay is an important metric that depicts the
provisioning performance of a GMPLS network. Longer LSP setup
delay will most likely incur higher overhead for the requesting
application, especially when the LSP duration itself is comparable
to the LSP setup delay.
o The minimum value of this metric provides an indication of the
delay that will likely be experienced when the LSP traversed the
shortest route at the lightest load in the control plane. As the
delay itself consists of several components, such as link
propagation delay and nodal processing delay, this metric also
reflects the status of control plane. For example, for LSPs
traversing the same route, longer setup delays may suggest
congestion in the control channel or high control element load.
For this reason, this metric is useful for testing and diagnostic
purposes.
o The observed variance in a sample of LSP setup delay metric values
variance may serve as an early indicator on the feasibility of
support of applications that have stringent setup delay
requirements.
The measurement of single uni-directional LSP setup delay instead of
bi-directional LSP setup delay is motivated by the following factors:
o Some applications may use only uni-directional LSPs rather than
bi-directional ones. For example, content delivery services with
multicasting may use only uni-directional LSPs.
4.2. Metric Name
single uni-directional LSP setup delay
4.3. Metric Parameters
o ID0, the ingress LSR ID
Sun & Zhang Expires February 27, 2010 [Page 10]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o ID1, the egress LSR ID
o T, a time when the setup is attempted
4.4. Metric Units
The value of single uni-directional LSP setup delay is either a real
number, or an undefined number of milliseconds.
4.5. Definition
The single uni-directional LSP setup delay from ingress node ID0 to
egress node ID1 [RFC3945] at T is dT means that ingress node ID0
sends the first bit of a PATH message packet to egress node ID1 at
wire-time T, and that ingress node ID0 received the last bit of
responding RESV message packet from egress node ID1 at wire-time
T+dT.
The single uni-directional LSP setup delay from ingress node ID0 to
egress node ID1 at T is undefined, means that ingress node ID0 sends
the first bit of PATH message packet to egress node ID1 at wire-time
T and that ingress node ID0 does not receive the corresponding RESV
message within a reasonable period of time.
The undefined value of this metric indicates an event of Single Uni-
directional LSP Setup Failure, and would be used to report a count or
an percentage of Single Uni-directional LSP Setup failures. See
section Section 14.4 for definitions of LSP setup/release failures.
4.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of uni-directional LSP setup delay at time T depends
on the clock resolution in the ingress node; but synchronization
between the ingress node and egress node is not required since
uni-directional LSP setup uses two-way signaling.
o A given methodology will have to include a way to determine
whether a latency value is infinite or whether it is merely very
large. Simple upper bounds MAY be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move micro mirrors. This physical
motion may take several milliseconds. But the common electronic
switches can finish the nodal processing within several
microseconds. So the uni-directional LSP setup delay varies
drastically from one network to another. In practice, the upper
bound should be chosen carefully and the value MUST be reported.
Sun & Zhang Expires February 27, 2010 [Page 11]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o If ingress node sends out the PATH message to set up an LSP, but
never receives the corresponding RESV message, the uni-directional
LSP setup delay MUST be set to undefined.
o If the ingress node sends out the PATH message to set up an LSP
but receives a PathErr message, the uni-directional LSP setup
delay MUST be set to undefined. There are many possible reasons
for this case. For example, the PATH message has invalid
parameters or the network does not have enough resource to set up
the requested LSP, etc.
4.7. Methodologies
Generally the methodology would proceed as follows:
o Make sure that the network has enough resource to set up the
requested LSP.
o At the ingress node, form the PATH message according to the LSP
requirements. A timestamp (T1) may be stored locally on the
ingress node when the PATH message packet is sent towards the
egress node.
o If the corresponding RESV message arrives within a reasonable
period of time, take the timestamp (T2) as soon as possible upon
receipt of the message. By subtracting the two timestamps, an
estimate of uni-directional LSP setup delay (T2 -T1) can be
computed.
o If the corresponding RESV message fails to arrive within a
reasonable period of time, the uni-directional LSP setup delay is
deemed to be undefined. Note that the 'reasonable' threshold is a
parameter of the methodology.
o If the corresponding response message is PathErr, the uni-
directional LSP setup delay is deemed to be undefined.
Sun & Zhang Expires February 27, 2010 [Page 12]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
5. A Singleton Definition for multiple Uni-directional LSP Setup Delay
This part defines a metric for multiple uni-directional Label
Switched Paths setup delay across a GMPLS network.
5.1. Motivation
Multiple uni-directional Label Switched Paths setup delay is useful
for several reasons:
o Carriers may require a large number of LSPs be set up during a
short time period. This request may arise e.g. as a consequence
to interruptions on established LSPs or other network failures.
o The time needed to setup a large number of LSPs during a short
time period can not be deduced from single LSP setup delay.
5.2. Metric Name
Multiple uni-directional LSPs setup delay
5.3. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o Lambda_m, a rate in reciprocal milliseconds
o X, the number of LSPs to setup
o T, a time when the first setup is attempted
5.4. Metric Units
The value of multiple uni-directional LSPs setup delay is either a
real number, or an undefined number of milliseconds.
5.5. Definition
Given Lambda_m and X, the multiple uni-directional LSPs setup delay
from the ingress node to the egress node [RFC3945] at T is dT means:
o ingress node ID0 sends the first bit of the first PATH message
packet to egress node ID1 at wire-time T
o all subsequent (X-1) PATH messages are sent according to the
specified Poisson process with arrival rate Lambda_m
Sun & Zhang Expires February 27, 2010 [Page 13]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o ingress node ID0 receives all corresponding RESV message packets
from egress node ID1, and
o ingress node ID0 receives the last RESV message packet at wire-
time T+dT
The multiple uni-directional LSPs setup delay at T is undefined,
means that ingress node ID0 sends all the PATH messages toward egress
node ID1 and the first bit of the first PATH message packet is sent
at wire-time T and that ingress node ID0 does not receive one or more
of the corresponding RESV messages within a reasonable period of
time.
The undefined value of this metric indicates an event of Multiple
Uni-directional LSP Setup Failure, and would be used to report a
count or an percentage of Multiple Uni-directional LSP Setup
failures. See section Section 14.4 for definitions of LSP setup/
release failures.
5.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of multiple uni-directional LSPs setup delay at time
T depends on the clock resolution in the ingress node; but
synchronization between the ingress node and egress node is not
required since uni-directional LSP setup uses two-way signaling.
o A given methodology will have to include a way to determine
whether a latency value is infinite or whether it is merely very
large. Simple upper bounds MAY be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move micro mirrors. This physical
motion may take several milliseconds. But electronic switches can
finish the nodal processing within several microseconds. So the
multiple uni-directional LSP setup delay varies drastically from
one network to another. In practice, the upper bound should be
chosen carefully and the value MUST be reported.
o If ingress node sends out the multiple PATH messages to set up the
LSPs, but never receives one or more of the corresponding RESV
messages, multiple uni-directional LSP setup delay MUST be set to
undefined.
o If ingress node sends out the PATH messages to set up the LSPs but
receives one or more PathErr messages, multiple uni-directional
LSPs setup delay MUST be set to undefined. There are many
possible reasons for this case. For example, one of the PATH
Sun & Zhang Expires February 27, 2010 [Page 14]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
messages has invalid parameters or the network has not enough
resource to set up the requested LSPs, etc.
o The arrival rate of the Poisson process Lambda_m should be chosen
carefully such that in the one hand the control plane is not
overburdened. On the other hand, the arrival rate is large enough
to meet the requirements of applications or services.
5.7. Methodologies
Generally the methodology would proceed as follows:
o Make sure that the network has enough resource to set up the
requested LSPs.
o At the ingress node, form the PATH messages according to the LSPs'
requirements.
o At the ingress node, select the time for each of the PATH messages
according to the specified Poisson process.
o At the ingress node, send out the PATH messages according to the
selected time.
o Store a timestamp (T1) locally on the ingress node when the first
PATH message packet is sent towards the egress node.
o If all of the corresponding RESV messages arrive within a
reasonable period of time, take the final timestamp (T2) as soon
as possible upon the receipt of all the messages. By subtracting
the two timestamps, an estimate of multiple uni-directional LSPs
setup delay (T2 -T1) can be computed.
o If one or more of the corresponding RESV messages fail to arrive
within a reasonable period of time, the multiple uni-directional
LSPs setup delay is deemed to be undefined. Note that the
'reasonable' threshold is a parameter of the methodology.
o If one or more of the corresponding response messages are PathErr,
the multiple uni-directional LSPs setup delay is deemed to be
undefined.
Sun & Zhang Expires February 27, 2010 [Page 15]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
6. A Singleton Definition for Single Bi-directional LSP Setup Delay
GMPLS allows establishment of bi-directional symmetric LSPs (not of
asymmetric LSPs). This part defines a metric for single bi-
directional LSP setup delay across a GMPLS network.
6.1. Motivation
Single bi-directional Label Switched Path setup delay is useful for
several reasons:
o LSP setup delay is an important metric that depicts the
provisioning performance of a GMPLS network. Longer LSP setup
delay will incur higher overhead for the requesting application,
especially when the LSP duration is comparable to the LSP setup
delay. Thus, measuring the setup delay is important for
application scheduling.
o The minimum value of this metric provides an indication of the
delay that will likely be experienced when the LSP traversed the
shortest route at the lightest load in the control plane. As the
delay itself consists of several components, such as link
propagation delay and nodal processing delay, this metric also
reflects the status of control plane. For example, for LSPs
traversing the same route, longer setup delays may suggest
congestion in the control channel or high control element load.
For this reason, this metric is useful for testing and diagnostic
purposes.
o LSP setup delay variance has different impact on applications.
Erratic variation in LSP setup delay makes it difficult to support
applications that have stringent setup delay requirement.
The measurement of single bi-directional LSP setup delay instead of
uni-directional LSP setup delay is motivated by the following
factors:
o Bi-directional LSPs are seen as a requirement for many GMPLS
networks. Its provisioning performance is important to
applications that generate bi-directional traffic.
6.2. Metric Name
Single bi-directional LSP setup delay
Sun & Zhang Expires February 27, 2010 [Page 16]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
6.3. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T, a time when the setup is attempted
6.4. Metric Units
The value of single bi-directional LSP setup delay is either a real
number, or an undefined number of milliseconds.
6.5. Definition
For a real number dT, the single bi-directional LSP setup delay from
ingress node ID0 to egress node ID1 at T is dT, means that ingress
node ID0 sends out the first bit of a PATH message including an
Upstream Label [RFC3473] heading for egress node ID1 at wire-time T,
egress node ID1 receives that packet, then immediately sends a RESV
message packet back to ingress node ID0, and that ingress node ID0
receives the last bit of the RESV message packet at wire-time T+dT.
The single bi-directional LSP setup delay from ingress node ID0 to
egress node ID1 at T is undefined, means that ingress node ID0 sends
the first bit of PATH message to egress node ID1 at wire-time T and
that ingress node ID0 does not receive that response packet within a
reasonable period of time.
The undefined value of this metric indicates an event of Single Bi-
directional LSP Setup Failure, and would be used to report a count or
an percentage of Single Bi-directional LSP Setup failures. See
section Section 14.4 for definitions of LSP setup/release failures.
6.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of single bi-directional LSP setup delay depends on
the clock resolution in the ingress node; but synchronization
between the ingress node and egress node is not required since
single bi-directional LSP setup uses two-way signaling.
o A given methodology will have to include a way to determine
whether a latency value is infinite or whether it is merely very
large. Simple upper bounds MAY be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move micro mirrors. This physical
Sun & Zhang Expires February 27, 2010 [Page 17]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
motion may take several milliseconds. But electronic switches can
finish the nodal processing within several microseconds. So the
bi-directional LSP setup delay varies drastically from one network
to another. In the process of bi-directional LSP setup, if the
downstream node overrides the label suggested by the upstream
node, the setup delay may also increase. Thus, in practice, the
upper bound should be chosen carefully and the value MUST be
reported.
o If the ingress node sends out the PATH message to set up the LSP,
but never receives the corresponding RESV message, single bi-
directional LSP setup delay MUST be set to undefined.
o If the ingress node sends out the PATH message to set up the LSP,
but receives PathErr message, single bi-directional LSP setup
delay MUST be set to undefined. There are many possible reasons
for this case. For example, the PATH message has invalid
parameters or the network has not enough resource to set up the
requested LSP.
6.7. Methodologies
Generally the methodology would proceed as follows:
o Make sure that the network has enough resource to set up the
requested LSP.
o At the ingress node, form the PATH message (including the Upstream
Label or suggested label) according to the LSP requirements. A
timestamp (T1) may be stored locally on the ingress node when the
PATH message packet is sent towards the egress node.
o If the corresponding RESV message arrives within a reasonable
period of time, take the final timestamp (T2) as soon as possible
upon the receipt of the message. By subtracting the two
timestamps, an estimate of bi-directional LSP setup delay (T2 -T1)
can be computed.
o If the corresponding RESV message fails to arrive within a
reasonable period of time, the single bi-directional LSP setup
delay is deemed to be undefined. Note that the 'reasonable'
threshold is a parameter of the methodology.
o If the corresponding response message is PathErr, the single bi-
directional LSP setup delay is deemed to be undefined.
Sun & Zhang Expires February 27, 2010 [Page 18]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
7. A Singleton Definition for multiple Bi-directional LSPs Setup Delay
This part defines a metric for multiple bi-directional LSPs setup
delay across a GMPLS network.
7.1. Motivation
multiple bi-directional LSPs setup delay is useful for several
reasons:
o Upon traffic interruption caused by network failure or network
upgrade, carriers may require a large number of LSPs be set up
during a short time period
o The time needed to setup a large number of LSPs during a short
time period can not be deduced by single LSP setup delay
7.2. Metric Name
Multiple bi-directional LSPs setup delay
7.3. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o Lambda_m, a rate in reciprocal milliseconds
o X, the number of LSPs to setup
o T, a time when the first setup is attempted
7.4. Metric Units
The value of multiple bi-directional LSPs setup delay is either a
real number, or an undefined number of milliseconds.
7.5. Definition
Given Lambda_m and X, for a real number dT, the multiple bi-
directional LSPs setup delay from ingress node to egress node at T is
dT, means that:
o ingress node ID0 sends the first bit of the first PATH message
heading for egress node ID1 at wire-time T
Sun & Zhang Expires February 27, 2010 [Page 19]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o all subsequent (X-1) PATH messages are sent according to the
specified Poisson process with arrival rate Lambda_m
o ingress node ID1 receives all corresponding RESV message packets
from egress node ID1, and
o ingress node ID0 receives the last RESV message packet at wire-
time T+dT
The multiple bi-directional LSPs setup delay from ingress node to
egress node at T is undefined, means that ingress node sends all the
PATH messages to egress node and that the ingress node fails to
receive one or more of the response RESV messages within a reasonable
period of time.
The undefined value of this metric indicates an event of Multiple Bi-
directional LSP Setup Failure, and would be used to report a count or
an percentage of Multiple Bi-directional LSP Setup failures. See
section Section 14.4 for definitions of LSP setup/release failures.
7.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of multiple bi-directional LSPs setup delay depends
on the clock resolution in the ingress node; but synchronization
between the ingress node and egress node is not required since bi-
directional LSP setup uses two-way signaling.
o A given methodology will have to include a way to determine
whether a latency value is infinite or whether it is merely very
large. Simple upper bounds MAY be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move micro mirrors. This physical
motion may take several milliseconds. But electronic switches can
finish the nodal process within several microseconds. So the
multiple bi-directional LSPs setup delay varies drastically from a
network to another. In the process of multiple bi-directional
LSPs setup, if the downstream node overrides the label suggested
by the upstream node, the setup delay may also increase. Thus, in
practice, the upper bound should be chosen carefully and the value
MUST be reported.
o If the ingress node sends out the PATH messages to set up the
LSPs, but never receives all the corresponding RESV messages, the
multiple bi-directional LSPs setup delay MUST be set to undefined.
Sun & Zhang Expires February 27, 2010 [Page 20]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o If the ingress node sends out the PATH messages to set up the
LSPs, but receives one or more responding PathErr messages, the
multiple bi-directional LSPs setup delay MUST be set to undefined.
There are many possible reasons for this case. For example, one
or more of the PATH messages have invalid parameters or the
network has not enough resource to set up the requested LSPs.
o The arrival rate of the Poisson process Lambda_m should be
carefully chosen such that on the one hand the control plane is
not overburdened. On the other hand, the arrival rate is large
enough to meet the requirements of applications or services.
7.7. Methodologies
Generally the methodology would proceed as follows:
o Make sure that the network has enough resource to set up the
requested LSPs.
o At the ingress node, form the PATH messages (including the
Upstream Label or suggested label) according to the LSPs'
requirements.
o At the ingress node, select the time for each of the PATH messages
according to the specified Poisson process.
o At the ingress node, send out the PATH messages according to the
selected time.
o Store a timestamp (T1) locally in the ingress node when the first
PATH message packet is sent towards the egress node.
o If all of the corresponding RESV messages arrive within a
reasonable period of time, take the final timestamp (T2) as soon
as possible upon the receipt of all the messages. By subtracting
the two timestamps, an estimate of multiple bi-directional LSPs
setup delay (T2 -T1) can be computed.
o If one or more of the corresponding RESV messages fail to arrive
within a reasonable period of time, the multiple bi-directional
LSPs setup delay is deemed to be undefined. Note that the
'reasonable' threshold is a parameter of the methodology.
o If one or more of the corresponding response messages are PathErr,
the multiple bi-directional LSPs setup delay is deemed to be
undefined.
Sun & Zhang Expires February 27, 2010 [Page 21]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
8. A Singleton Definition for LSP Graceful Release Delay
There are two different kinds of LSP release mechanisms in GMPLS
networks: graceful release and forceful release. This document does
not take forceful LSP release procedure into account.
8.1. Motivation
LSP graceful release delay is useful for several reasons:
o The LSP graceful release delay is part of the total cost of
dynamic LSP provisioning. For some short duration applications,
the LSP release time can not be ignored
o The LSP graceful release procedure is more preferred in a GMPLS
controlled network, particularly the optical networks. Since it
doesn't trigger restoration/protection, it is "alarm-free
connection deletion" in [RFC4208].
8.2. Metric Name
LSP graceful release delay
8.3. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T, a time when the release is attempted
8.4. Metric Units
The value of LSP graceful release delay is either a real number, or
an undefined number of milliseconds.
8.5. Definition
There are two different LSP graceful release procedures, one is
initiated by the ingress node, and another is initiated by the egress
node. The two procedures are depicted in [RFC3473]. We define the
graceful LSP release delay for these two procedures separately.
For a real number dT, the LSP graceful release delay from ingress
node ID0 to egress node ID1 at T is dT, means that ingress node ID0
sends the first bit of a PATH message including Admin Status Object
with the Reflect (R) and Delete (D) bits set to the egress node at
wire-time T, that egress node ID1 receives that packet, then
Sun & Zhang Expires February 27, 2010 [Page 22]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
immediately sends a RESV message including Admin Status Object with
the Delete (D) bit set back to the ingress node. Ingress node ID0
sends out PathTear downstream to remove the LSP, and egress node ID1
receives the last bit of PathTear packet at wire-time T+dT.
Also as an option, upon receipt of the PATH message including Admin
Status Object with the Reflect (R) and Delete (D) bits set, egress
node ID1 may respond with PathErr message with the Path_State_Removed
flag set.
The LSP graceful release delay from ingress node ID0 to egress node
ID1 at T is undefined, means that ingress node ID0 sends the first
bit of PATH message to egress node ID1 at wire-time T and that
(either egress node does not receive the PATH packet, egress node
does not send corresponding RESV message packet in response, or
ingress node does not receive that RESV packet, and) egress node ID1
does not receive the PathTear within a reasonable period of time.
The LSP graceful release delay from egress node ID1 to ingress node
ID0 at T is dT, means that egress node ID1 sends the first bit of a
RESV message including Admin Status Object with setting the Reflect
(R) and Delete (D) bits to ingress node at wire-time T. Ingress node
ID0 sends out PathTear downstream to remove the LSP, and egress node
ID1 receives the last bit of PathTear packet at wire-time T+dT.
The LSP graceful release delay from egress node ID1 to ingress node
ID0 at T is undefined, means that egress node ID1 sends the first bit
of RESV message including Admin Status Object with setting the
Reflect (R) and Delete (D) bits to ingress node ID0 at wire-time T
and that (either ingress node does not receive the RESV packet, or
ingress node does not send PathTear message packet in response, and)
egress node ID1 does not receive the PathTear within a reasonable
period of time.
The undefined value of this metric indicates an event of LSP Graceful
Release Failure, and would be used to report a count or an percentage
of LSP Graceful Release failures. See section Section 14.4 for
definitions of LSP setup/release failures.
8.6. Discussion
The following issues are likely to come up in practice:
o In the first (second) circumstance, the accuracy of LSP graceful
release delay at time T depends on the clock resolution in the
ingress (egress) node. In the first circumstance, synchronization
between the ingress node and egress node is required; but not in
the second circumstance;
Sun & Zhang Expires February 27, 2010 [Page 23]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o A given methodology has to include a way to determine whether a
latency value is infinite or whether it is merely very large.
Simple upper bounds MAY be used. But the upper bound should be
chosen carefully in practice and the value MUST be reported;
o In the first circumstance, if the ingress node sends out PATH
message including Admin Status Object with the Reflect (R) and
Delete (D) bits set to initiate LSP graceful release, but the
egress node never receives the corresponding PathTear message, LSP
graceful release delay MUST be set to undefined.
o In the second circumstance, if the egress node sends out the RESV
message including Admin Status Object with the Reflect (R) and
Delete (D) bits set to initiate LSP graceful release, but never
receives the corresponding PathTear message, LSP graceful release
delay MUST be set to undefined.
8.7. Methodologies
In the first circumstance, the methodology may proceed as follows:
o Make sure the LSP to be deleted is set up;
o At the ingress node, form the PATH message including Admin Status
Object with the Reflect (R) and Delete (D) bits set. A timestamp
(T1) may be stored locally on the ingress node when the PATH
message packet is sent towards the egress node;
o Upon receiving the PATH message including Admin Status Object with
the Reflect (R) and Delete (D) bits set, the egress node sends a
RESV message including Admin Status Object with the Delete (D) and
Reflect (R) bits set. Alternatively, the egress node sends a
PathErr message with the Path_State_Removed flag set upstream;
o When the ingress node receive the RESV message or the PathErr
message, it sends a PathTear message to remove the LSP;
o The egress node takes a timestamp (T2) once it receives the last
bit of the PathTear message. The LSP graceful release delay is
then (T2-T1).
o If the ingress node sends the PATH message downstream, but the
egress node fails to receive the PathTear message within a
reasonable period of time, the LSP graceful release delay is
deemed to be undefined. Note that the 'reasonable' threshold is a
parameter of the methodology.
In the second circumstance, the methodology would proceed as follows:
Sun & Zhang Expires February 27, 2010 [Page 24]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
o Make sure the LSP to be deleted is set up;
o On the egress node, form the RESV message including Admin Status
Object with the Reflect (R) and Delete (D) bits set. A timestamp
may be stored locally on the egress node when the RESV message
packet is sent towards the ingress node;
o Upon receiving the Admin Status Object with the Reflect (R) and
Delete (D) bits set in the RESV message, the ingress node sends a
PathTear message downstream to remove the LSP;
o Egress node takes a timestamp (T2) once it receives the last bit
of the PathTear message. The LSP graceful release delay is then
(T2-T1).
o If the egress node sends the RESV message upstream, but it fails
to receive the PathTear message within a reasonable period of
time, the LSP graceful release delay is deemed to be undefined.
Note that the 'reasonable' threshold is a parameter of the
methodology.
Sun & Zhang Expires February 27, 2010 [Page 25]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
9. A Definition for Samples of Single Uni-directional LSP Setup Delay
In Section 4, we have defined the singleton metric of Single uni-
directional LSP setup delay. Now we define how to get one particular
sample of Single uni-directional LSP setup delay. Sampling is to
select a particular potion of singleton values of the given
parameters. Like in [RFC2330], we use Poisson sampling as an
example.
9.1. Metric Name
Single uni-directional LSP setup delay sample
9.2. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T0, a time
o Tf, a time
o Lambda, a rate in the reciprocal milliseconds
o Th, LSP holding time
o Td, the maximum waiting time for successful setup
9.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when setup is attempted
o dT, either a real number or an undefined number of milliseconds.
9.4. Definition
Given T0, Tf, and lambda, compute a pseudo-random Poisson process
beginning at or before T0, with average arrival rate lambda, and
ending at or after Tf. Those time values greater than or equal to T0
and less than or equal to Tf are then selected. At each of the times
in this process, we obtain the value of uni-directional LSP setup
delay sample at this time. The value of the sample is the sequence
made up of the resulting <time, LSP setup delay> pairs. If there are
no such pairs, the sequence is of length zero and the sample is said
to be empty.
Sun & Zhang Expires February 27, 2010 [Page 26]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
9.5. Discussion
The parameter lambda should be carefully chosen. If the rate is too
high, too frequent LSP setup/release procedure will result in high
overhead in the control plane. In turn, the high overhead will
increase uni-directional LSP setup delay. On the other hand if the
rate is too low, the sample could not completely reflect the dynamic
provisioning performance of the GMPLS network. The appropriate
lambda value depends on the given network.
The parameters Td should be carefully chosen. Different switching
technologies may vary significantly in performing a cross-connect
operation. At the same time, the time needed in setting up an LSP
under different traffic may also vary significantly.
In the case of active measurement, the parameters Th should be
carefully chosen. The combination of lambda and Th reflects the load
of the network. The selection of Th should take into account that
the network has sufficient resource to perform subsequent tests. The
value of Th MAY be constant during one sampling process for
simplicity considerations.
Note that for online or passive measurements, the arrival rate and
LSP holding time are determined by actual traffic, hence in this case
Lambda and Th are not input parameters.
9.6. Methodologies
o Select the times using the specified Poisson arrival process, and
o Set up the LSP as the methodology for the singleton uni-
directional LSP setup delay, and obtain the value of uni-
directional LSP setup delay
o Release the LSP after Th, and wait for the next Poisson arrival
event
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival event arrives and the
LSP setup procedure is initiated. If there is resource contention
between the two LSPs, the LSP setup may fail. Ways to avoid such
contention are outside the scope of this document.
9.7. Typical testing cases
Sun & Zhang Expires February 27, 2010 [Page 27]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
9.7.1. With no LSP in the Network
9.7.1.1. Motivation
Single uni-directional LSP setup delay with no LSP in the network is
important because this reflects the inherent delay of an RSVP-TE
implementation. The minimum value provides an indication of the
delay that will likely be experienced when an LSP traverses the
shortest route with the lightest load in the control plane.
9.7.1.2. Methodologies
Make sure that there is no LSP in the network, and proceed with the
methodologies described in Section 9.6.
9.7.2. With a number of LSPs in the Network
9.7.2.1. Motivation
Single uni-directional LSP setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considerable load. This delay may vary
significantly as the number of existing LSPs vary. It can be used as
a scalability metric of an RSVP-TE implementation.
9.7.2.2. Methodologies
Setup the required number of LSPs, and wait until the network reaches
a stable state, then proceed with the methodologies described in
Section 9.6.
Sun & Zhang Expires February 27, 2010 [Page 28]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
10. A Definition for Samples of Multiple Uni-directional LSPs Setup
Delay
In Section 5, we have defined the singleton metric of multiple uni-
directional LSPs setup delay. Now we define how to get one
particular sample of multiple uni-directional LSP setup delay.
Sampling is to select a particular potion of singleton values of the
given parameters. Like in [RFC2330], we use Poisson sampling as an
example.
10.1. Metric Name
Multiple uni-directional LSPs setup delay sample
10.2. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T0, a time
o Tf, a time
o Lambda_m, a rate in the reciprocal milliseconds
o Lambda, a rate in the reciprocal milliseconds
o X, the number of LSPs to setup
o Th, LSP holding time
o Td, the maximum waiting time for successful multiple uni-
directional LSPs setup
10.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when the first setup is attempted
o dT, either a real number or an undefined number of milliseconds.
10.4. Definition
Given T0, Tf, and lambda, compute a pseudo-random Poisson process
beginning at or before T0, with average arrival rate lambda, and
ending at or after Tf. Those time values greater than or equal to T0
Sun & Zhang Expires February 27, 2010 [Page 29]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
and less than or equal to Tf are then selected. At each of the time
in this process, we obtain the value of multiple uni-directional LSP
setup delay sample at this time. The value of the sample is the
sequence made up of the resulting <time, setup delay> pairs. If
there are no such pairs, the sequence is of length zero and the
sample is said to be empty.
10.5. Discussion
The parameter lambda is used as arrival rate of "bacth uni-
directional LSPs setup" operation. It regulates the interval in
between each batch operation. The parameter lambda_m is used within
each batch operation, as described in Section 5.
The parameters lambda and lambda_m should be carefully chosen. If
the rate is too high, too frequent LSP setup/release procedure will
result in high overhead in the control plane. In turn, the high
overhead will increase uni-directional LSP setup delay. On the other
hand if the rate is too low, the sample could not completely reflect
the dynamic provisioning performance of the GMPLS network. The
appropriate lambda and lambda_m value depends on the given network.
The parameters Td should be carefully chosen. Different switching
technologies may vary significantly in performing a cross-connect
operation. At the same time, the time needed in setting up an LSP
under different traffic may also vary significantly.
10.6. Methodologies
o Select the times using the specified Poisson arrival process, and
o Set up the LSP as the methodology for the singleton multiple uni-
directional LSPs setup delay, and obtain the value of multiple
uni-directional LSPs setup delay
o Release the LSP after Th, and wait for the next Poisson arrival
event
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival event arrives and the
LSP setup procedure is initiated. If there is resource contention
between the two LSPs, the LSP setup may fail. Ways to avoid such
contention are outside the scope of this document.
10.7. Typical testing cases
Sun & Zhang Expires February 27, 2010 [Page 30]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
10.7.1. With No LSP in the Network
10.7.1.1. Motivation
Multiple uni-directional LSP setup delay with no LSP in the network
is important because this reflects the inherent delay of an RSVP-TE
implementation. The minimum value provides an indication of the
delay that will likely be experienced when LSPs traverse the shortest
route with the lightest load in the control plane.
10.7.1.2. Methodologies
Make sure that there is no LSP in the network, and proceed with the
methodologies described in Section 10.6.
10.7.2. With a Number of LSPs in the Network
10.7.2.1. Motivation
Multiple uni-directional LSPs setup delay with a number of LSPs in
the network is important because it reflects the performance of an
operational network with considerable load. This delay can vary
significantly as the number of existing LSPs vary. It can be used as
a scalability metric of an RSVP-TE implementation.
10.7.2.2. Methodologies
Setup the required number of LSPs, and wait until the network reaches
a stable state, then proceed with the methodologies described in
Section 10.6..
Sun & Zhang Expires February 27, 2010 [Page 31]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
11. A Definition for Samples of Single Bi-directional LSP Setup Delay
In Section 6, we have defined the singleton metric of Single Bi-
directional LSP setup delay. Now we define how to get one particular
sample of Single Bi-directional LSP setup delay. Sampling is to
select a particular potion of singleton values of the given
parameters. Like in [RFC2330], we use Poisson sampling as an
example.
11.1. Metric Name
Single Bi-directional LSP setup delay sample with no LSP in the
network
11.2. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T0, a time
o Tf, a time
o Lambda, a rate in the reciprocal milliseconds
o Th, LSP holding time
o Td, the maximum waiting time for successful setup
11.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when setup is attempted
o dT, either a real number or an undefined number of milliseconds.
11.4. Definition
Given T0, Tf, and lambda, compute a pseudo-random Poisson process
beginning at or before T0, with average arrival rate lambda, and
ending at or after Tf. Those time values greater than or equal to T0
and less than or equal to Tf are then selected. At each of the times
in this process, we obtain the value of Bi-directional LSP setup
delay sample at this time. The value of the sample is the sequence
made up of the resulting <time, LSP setup delay> pairs. If there are
no such pairs, the sequence is of length zero and the sample is said
Sun & Zhang Expires February 27, 2010 [Page 32]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
to be empty.
11.5. Discussion
The parameters lambda should be carefully chosen. If the rate is too
high, too frequent LSP setup/release procedure will result in high
overhead in the control plane. In turn, the high overhead will
increase Bi-directional LSP setup delay. On the other hand if the
rate is too low, the sample could not completely reflect the dynamic
provisioning performance of the GMPLS network. The appropriate
lambda value depends on the given network.
The parameters Td should be carefully chosen. Different switching
technologies may vary significantly in performing a cross-connect
operation. At the same time, the time needed in setting up an LSP
under different traffic may also vary significantly.
In the case of active measurement, the parameters Th should be
carefully chosen. The combination of lambda and Th reflects the load
of the network. The selection of Th SHOULD take into account that
the network has sufficient resource to perform subsequent tests. The
value of Th MAY be constant during one sampling process for
simplicity considerations.
Note that for online or passive measurements, the arrival rate and
the LSP holding time are determined by actual traffic, hence in this
case Lambda and Th are not input parameters.
11.6. Methodologies
o Select the times using the specified Poisson arrival process, and
o Set up the LSP as the methodology for the singleton bi-directional
LSP setup delay, and obtain the value of bi-directional LSP setup
delay
o Release the LSP after Th, and wait for the next Poisson arrival
event
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival event arrives and the
LSP setup procedure is initiated. If there is resource contention
between the two LSPs, the LSP setup may fail. Ways to avoid such
contention are outside the scope of this document.
Sun & Zhang Expires February 27, 2010 [Page 33]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
11.7. Typical testing cases
11.7.1. With No LSP in the Network
11.7.1.1. Motivation
Single bi-directional LSP setup delay with no LSP in the network is
important because this reflects the inherent delay of an RSVP-TE
implementation. The minimum value provides an indication of the
delay that will likely be experienced when an LSP traverses the
shortest route with the lightest load in the control plane.
11.7.1.2. Methodologies
Make sure that there is no LSP in the network, and proceed with the
methodologies described in Section 11.6.
11.7.2. With a Number of LSPs in the Network
11.7.2.1. Motivation
Single bi-directional LSP setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considerable load. This delay can vary
significantly as the number of existing LSPs varies. It can be used
as a scalability metric of an RSVP-TE implementation.
11.7.2.2. Methodologies
Setup the required number of LSPs, and wait until the network reaches
a stable state, then proceed with the methodologies described in
Section 11.6. .
Sun & Zhang Expires February 27, 2010 [Page 34]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
12. A Definition for Samples of Multiple Bi-directional LSPs Setup
Delay
In Section 7, we have defined the singleton metric of multiple bi-
directional LSPs setup delay. Now we define how to get one
particular sample of multiple bi-directional LSP setup delay.
Sampling is to select a particular potion of singleton values of the
given parameters. Like in [RFC2330], we use Poisson sampling as an
example.
12.1. Metric Name
Multiple bi-directional LSPs setup delay sample
12.2. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T0, a time
o Tf, a time
o Lambda_m, a rate in the reciprocal milliseconds
o Lambda, a rate in the reciprocal milliseconds
o X, the number of LSPs to setup
o Th, LSP holding time
o Td, the maximum waiting time for successful multiple uni-
directional LSPs setup
12.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when the first setup is attempted
o dT, either a real number or an undefined number of milliseconds.
12.4. Definition
Given T0, Tf, and lambda, compute a pseudo-random Poisson process
beginning at or before T0, with average arrival rate lambda, and
ending at or after Tf. Those time values greater than or equal to T0
Sun & Zhang Expires February 27, 2010 [Page 35]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
and less than or equal to Tf are then selected. At each of the times
in this process, we obtain the value of multiple uni-directional LSP
setup delay sample at this time. The value of the sample is the
sequence made up of the resulting <time, setup delay> pairs. If
there are no such pairs, the sequence is of length zero and the
sample is said to be empty.
12.5. Discussion
The parameter lambda is used as arrival rate of "bacth bi-directional
LSPs setup" operation. It regulates the interval in between each
batch operation. The parameter lambda_m is used within each batch
operation, as described in Section 7.
The parameters lambda and lambda_m should be carefully chosen. If
the rate is too high, too frequent LSP setup/release procedure will
result in high overhead in the control plane. In turn, the high
overhead will increase uni-directional LSP setup delay. On the other
hand if the rate is too low, the sample could not completely reflect
the dynamic provisioning performance of the GMPLS network. The
appropriate lambda and lambda_m value depends on the given network.
The parameters Td should be carefully chosen. Different switching
technologies may vary significantly in performing a cross-connect
operation. At the same time, the time needed in setting up an LSP
under different traffic may also vary significantly.
12.6. Methodologies
o Select the times using the specified Poisson arrival process, and
o Set up the LSP as the methodology for the singleton multiple bi-
directional LSPs setup delay, and obtain the value of multiple
uni-directional LSPs setup delay
o Release the LSP after Th, and wait for the next Poisson arrival
event
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival event arrives and the
LSP setup procedure is initiated. If there is resource contention
between the two LSPs, the LSP setup may fail. Ways to avoid such
contention are outside the scope of this document.
12.7. Typical testing cases
Sun & Zhang Expires February 27, 2010 [Page 36]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
12.7.1. With No LSP in the Network
12.7.1.1. Motivation
Multiple bi-directional LSPs setup delay with no LSP in the network
is important because this reflects the inherent delay of an RSVP-TE
implementation. The minimum value provides an indication of the
delay that will likely be experienced when an LSPs traverse the
shortest route with the lightest load in the control plane.
12.7.1.2. Methodologies
Make sure that there is no LSP in the network, and proceed with the
methodologies described in Section 10.6.
12.7.2. With a Number of LSPs in the Network
12.7.2.1. Motivation
multiple bi-directional LSPs setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considerable load. This delay may vary
significantly as the number of existing LSPs vary. It may be used as
a scalability metric of an RSVP-TE implementation.
12.7.2.2. Methodologies
Setup the required number of LSPs, and wait until the network reaches
a stable state, then proceed with the methodologies described in
Section 12.6..
Sun & Zhang Expires February 27, 2010 [Page 37]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
13. A Definition for Samples of LSP Graceful Release Delay
In Section 8, we have defined the singleton metric of LSP graceful
release delay. Now we define how to get one particular sample of LSP
graceful release delay. We also use Poisson sampling as an example.
13.1. Metric Name
LSP graceful release delay sample
13.2. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T0, a time
o Tf, a time
o Lambda, a rate in reciprocal milliseconds
o Td, the maximum waiting time for successful LSP release
13.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time, and
o dT, either a real number or an undefined number of milliseconds.
13.4. Definition
Given T0, Tf, and lambda, we compute a pseudo-random Poisson process
beginning at or before T0, with average arrival rate lambda, and
ending at or after Tf. Those time values greater than or equal to T0
and less than or equal to Tf are then selected. At each of the times
in this process, we obtain the value of LSP graceful release delay
sample at this time. The value of the sample is the sequence made up
of the resulting <time, LSP graceful delay> pairs. If there are no
such pairs, the sequence is of length zero and the sample is said to
be empty.
13.5. Discussion
The parameter lambda should be carefully chosen. If the rate is too
large, too frequent LSP setup/release procedure will result in high
Sun & Zhang Expires February 27, 2010 [Page 38]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
overhead in the control plane. In turn, the high overhead will
increase uni-directional LSP setup delay. On the other hand if the
rate is too small, the sample could not completely reflect the
dynamic provisioning performance of the GMPLS network. The
appropriate lambda value depends on the given network.
13.6. Methodologies
Generally the methodology would proceed as follows:
o Setup the LSP to be deleted
o Select the times using the specified Poisson arrival process, and
o Release the LSP as the methodology for the singleton LSP graceful
release delay, and obtain the value of LSP graceful release delay
o Setup the LSP, and restart the Poisson arrival process, wait for
the next Poisson arrival event
Sun & Zhang Expires February 27, 2010 [Page 39]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
14. Some Statistics Definitions for Metrics to Report
Given the samples of the performance metric, we now offer several
statistics of these samples to report. From these statistics, we can
draw some useful conclusions of a GMPLS network. The value of these
metrics is either a real number, or an undefined number of
milliseconds. In the following discussion, we only consider the
finite values.
14.1. The Minimum of Metric
The minimum of metric is the minimum of all the dT values in the
sample. In computing this, undefined values SHOULD be treated as
infinitely large. Note that this means that the minimum could thus
be undefined if all the dT values are undefined. In addition, the
metric minimum SHOULD be set to undefined if the sample is empty.
14.2. The Median of Metric
Metric median is the median of the dT values in the given sample. In
computing the median, the undefined values MUST NOT be counted in.
14.3. The percentile of Metric
The percentile of Metric is defined as: given a metric and a percent
X between 0% and 100%, the Xth percentile of all the dT values in the
sample." In addition, the percentile is undefined if the sample is
empty.
Example: suppose we take a sample and the results are: Stream1 = <
<T1, 100 msec>, <T2, 110 msec>, <T3, undefined>, <T4, 90 msec>, <T5,
500 msec> >
Then the 50th percentile would be 110 msec, since 90 msec and 100
msec are smaller, and 110 and 500 msec are larger (undefined values
are not counted in).
14.4. Failure statistics of Metric
In the process of LSP setup/release, it may fail due to various
reasons. For example, setup/release may fail when the control plane
is overburdened or when there is resource shortage in one of the
intermediate nodes. Since the setup/release failure may have
significant impact on network operation, it is worthwhile to report
each failure cases, so that appropriate operations can be performed
to check the possible implementation,configuration or other
deficiencies.
Sun & Zhang Expires February 27, 2010 [Page 40]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
Five types of failure events are defined in previous sections:
o Single Uni-directional LSP Setup Failure
o Multiple Uni-directional LSP Setup Failure
o Single Bi-directional LSP Setup Failure
o Multiple Bi-directional LSP Setup Failure
o LSP graceful release failure
Given the samples of the performance metric, we now offer two
statistics of failure events of these samples to report.
14.4.1. Failure Count
Failure Count is defined as the number of the undefined value of the
corresponding performance metric (failure events) in a sample. The
unit of Failure Count is numerical.
14.4.2. Failure Ratio
Failure Ratio is the percentage of the number of failure events to
the total number of requests in a sample. The calculation for
Failure Ratio is defined as follows:
X type failure ratio = Number of X type failure events/(Number of
valid X type metric values + Number of X type failure events) * 100%.
Sun & Zhang Expires February 27, 2010 [Page 41]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
15. Discussion
It is worthwhile to point out that:
o The uni-directional/bi-directional LSP setup delay is one ingress-
egress round trip time plus processing time. But in this
document, uni-directional/bi-directional LSP setup delay has not
taken the processing time in the end nodes (ingress or/and egress)
into account. The timestamp T2 is taken after the endpoint node
receives it. Actually, the last node has to take some time to
process local procedure. Similarly, in the LSP graceful release
delay, the memo has not considered the processing time in the end
node.
o This document assumes that the correct procedures for installing
the data plane are followed as described in [RFC3209], [RFC3471],
and [RFC3473]. That is, by the time the egress receives and
processes a Path message, it is safe for the egress to transmit
data on the reverse path, and by the time the ingress receives and
processes a RESV message it is safe for the ingress to transmit
data on the forward path. See
[I-D.shiomoto-ccamp-switch-programming] for detailed explanations.
This document does not include any verification that the
implementations of the control plane software are conformant,
although such tests MAY be constructed with the use of suitable
signal generation test equipment. In [I-D.sun-ccamp-dpm], we
defined a series of metrics to do such verifications. However, it
is RECOMMENDED that both the measurements defined in this document
and the measurements defined in [I-D.sun-ccamp-dpm] are performed
to complement each other.
o Note that, in implementing the tests described in this document a
tester should be sure to measure the time taken for the control
plane messages including the processing of those messages by the
nodes under test.
o Bi-directional LSPs may be setup using three way signalling, where
the initiating node will send a RESV_CONF message downstream upon
receiving the RESV message. The RESV_CONF message is used to
notify the terminate node that it can transfer data upstream.
Actually, both direction should be ready to transfer data when the
RESV message is received by the initiate node. Therefore, the bi-
directional LSP setup delay defined in this document does not take
the confirmation procedure into account.
Sun & Zhang Expires February 27, 2010 [Page 42]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
16. Security Considerations
Samples of the metrics can be obtained in either active or passive
manners.
In active measurement, ingress nodes inject probing messages into the
control plane. The measurement parameters must be carefully selected
so that the measurements inject trivial amounts of additional traffic
into the networks they measure. If they inject "too much" traffic,
they can skew the results of the measurement, and in extreme cases
cause congestion and denial of service.
When samples of the metrics are collected in a passive manner, e.g.,
by monitoring the operations on real-life LSPs, the implementation of
the monitoring and reporting mechanism must be careful so that they
will not be used to attack the control plane.
Besides, the security considerations pertaining to the original RSVP
protocol [RFC2205] and its TE extensions [RFC3209] also remain
relevant.
Sun & Zhang Expires February 27, 2010 [Page 43]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
17. IANA Considerations
This document makes no requests for IANA action.
Sun & Zhang Expires February 27, 2010 [Page 44]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
18. Acknowledgements
We wish to thank Dan Li, Fang Liu (Christine), Zafar Ali, Monique
Morrow, Adrian Farrel, Deborah Brungard, Lou Berger, Thomas D. Nadeau
for their comments and helps.
We wish to thank experts from IPPM and BMWG - Reinhard Schrage, Al
Morton and Henk Uijterwaal, for reviewing this document.
This document contains ideas as well as text that have appeared in
existing IETF documents. The authors wish to thank G. Almes, S.
Kalidindi and M. Zekauskas.
We also wish to thank Weisheng Hu, Yaohui Jin and Wei Guo in the
state key laboratory of advanced optical communication systems and
networks for the valuable comments. We also wish to thank the
support from NSFC and 863 program of China.
Sun & Zhang Expires February 27, 2010 [Page 45]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
19. References
19.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2679] Almes, G., Kalidindi, S., and M. Zekauskas, "A One-way
Delay Metric for IPPM", RFC 2679, September 1999.
[RFC2681] Almes, G., Kalidindi, S., and M. Zekauskas, "A Round-trip
Delay Metric for IPPM", RFC 2681, September 1999.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", RFC 3945, October 2004.
[RFC4208] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS) User-
Network Interface (UNI): Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Support for the Overlay
Model", RFC 4208, October 2005.
19.2. Informative References
[I-D.shiomoto-ccamp-switch-programming]
Shiomoto, K. and A. Farrel, "Advice on When It is Safe to
Start Sending Data on Label Switched Paths Established
Using RSVP-TE", draft-shiomoto-ccamp-switch-programming-00
(work in progress), February 2009.
[I-D.sun-ccamp-dpm]
Sun, W., Zhang, G., Gao, J., Xie, G., Papneja, R., Gu, B.,
Sun & Zhang Expires February 27, 2010 [Page 46]
Internet-Draft LSP Dynamic PPM in GMPLS Networks August 2009
Wei, X., Otani, T., and R. Jing, "Label Switched Path
(LSP) Data Path Delay Metric in Generalized MPLS/ MPLS-TE
Networks", draft-sun-ccamp-dpm-00 (work in progress),
June 2009.
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
"Framework for IP Performance Metrics", RFC 2330,
May 1998.
Sun & Zhang Expires February 27, 2010 [Page 47]
Internet-Draft LSP Dynamic PPM in GMPLS Networks July 2009
Authors' Addresses
Weiqiang Sun
Shanghai Jiao Tong University
800 Dongchuan Road
Shanghai 200240
CN
Phone: +86 21 3420 5359
Email: sunwq@mit.edu
Guoying Zhang
China Academy of Telecommunication Research,MIIT,China.
No.11 YueTan South Street
Beijing 100045
CN
Phone: +86 1068094272
Email: zhangguoying@mail.ritt.com.cn
Jianhua Gao
Huawei Technologies Co., LTD.
CN
Phone: +86 755 28973237
Email: gjhhit@huawei.com
Guowu Xie
University of California, Riverside
900 University Ave.
Riverside, CA 92521
USA
Phone: +1 951 237 8825
Email: xieg@cs.ucr.edu
Rajiv Papneja
Isocore
12359 Sunrise Valley Drive, STE 100
Reston, VA 20190
USA
Phone: +1 703 860 9273
Email: rpapneja@isocore.com
Sun & Zhang Expires January 3, 2010 [Page 48]
Internet-Draft LSP Dynamic PPM in GMPLS Networks January 2009
Bin Gu
IXIA
Oriental Kenzo Plaza 8M,48 Dongzhimen Wai Street,Dongcheng District
Beijing 200240
CN
Phone: +86 13611590766
Email: BGu@ixiacom.com
Xueqin Wei
Fiberhome Telecommunicaiton Technology Co.,Ltd.
Wuhan
CN
Phone: +86 13871127882
Email: xqwei@fiberhome.com.cn
Tomohiro Otani
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Kamifukuoka Saitama
356-8502
Japan
Phone: +81-49-278-7357
Email: otani@kddilabs.jp
Ruiquan Jing
China Telecom Beijing Research Institute
118 Xizhimenwai Avenue
Beijing 100035
CN
Phone: +86-10-58552000
Email: jingrq@ctbri.com.cn
Sun & Zhang Expires January 3, 2010 [Page 49]