Network Working Group W. Sun, Ed.
Internet-Draft SJTU
Intended status: Standards Track G. Zhang, Ed.
Expires: September 29, 2009 CATR
March 28, 2009
Label Switched Path (LSP) Dynamic Provisioning Performance Metrics in
Generalized MPLS Networks
draft-ietf-ccamp-lsp-dppm-05.txt
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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
Multiplexors (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 Dynamicly 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. They can also be used in operational networks for
carriers to monitor the control plane performance in realtime.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. Overview of Performance Metrics . . . . . . . . . . . . . . . 7
3. A Singleton Definition for Single Unidirectional LSP Setup
Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 8
3.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 9
3.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 9
3.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 9
3.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 10
4. A Singleton Definition for multiple Unidirectional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 11
4.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 11
4.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 11
4.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 12
4.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 13
5. A Singleton Definition for Single Bidirectional LSP Setup
Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 14
5.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 14
5.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 15
5.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 15
5.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 15
5.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 16
6. A Singleton Definition for multiple Bidirectional LSPs
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 17
6.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 17
6.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 17
6.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 17
6.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 17
6.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 18
6.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 19
7. A Singleton Definition for LSP Graceful Release Delay . . . . 20
7.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . 20
7.2. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 20
7.3. Metric Parameters . . . . . . . . . . . . . . . . . . . . 20
7.4. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 20
7.5. Definition . . . . . . . . . . . . . . . . . . . . . . . . 20
7.6. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 21
7.7. Methodologies . . . . . . . . . . . . . . . . . . . . . . 22
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8. A Definition for Samples of Single Unidirectional LSP
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 24
8.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 24
8.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 24
8.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 24
8.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 25
8.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 25
8.7. Typical testing cases . . . . . . . . . . . . . . . . . . 25
8.7.1. With No LSP in the Network . . . . . . . . . . . . . . 26
8.7.2. With a Number of LSPs in the Network . . . . . . . . . 26
9. A Definition for Samples of Multiple Unidirectional LSPs
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 27
9.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 27
9.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 27
9.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 27
9.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 27
9.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 28
9.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 28
9.7. Typical testing cases . . . . . . . . . . . . . . . . . . 28
9.7.1. With No LSP in the Network . . . . . . . . . . . . . . 28
9.7.2. With a Number of LSPs in the Network . . . . . . . . . 29
10. A Definition for Samples of Single Bidirectional LSP Setup
Delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 30
10.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 30
10.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 30
10.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 30
10.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 31
10.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 31
10.7. Typical testing cases . . . . . . . . . . . . . . . . . . 31
10.7.1. With No LSP in the Network . . . . . . . . . . . . . . 32
10.7.2. With a Number of LSPs in the Network . . . . . . . . . 32
11. A Definition for Samples of Multiple Bidirectional LSPs
Setup Delay . . . . . . . . . . . . . . . . . . . . . . . . . 33
11.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 33
11.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 33
11.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 33
11.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 33
11.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 34
11.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 34
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 . . . . . . . . . 35
12. A Definition for Samples of LSP Graceful Release Delay . . . . 36
12.1. Metric Name . . . . . . . . . . . . . . . . . . . . . . . 36
12.2. Metric Parameters . . . . . . . . . . . . . . . . . . . . 36
12.3. Metric Units . . . . . . . . . . . . . . . . . . . . . . . 36
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12.4. Definition . . . . . . . . . . . . . . . . . . . . . . . . 36
12.5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 36
12.6. Methodologies . . . . . . . . . . . . . . . . . . . . . . 37
13. Discussion for unsuccessful setup/release cases . . . . . . . 38
14. Some Statistics Definitions for Metrics to Report . . . . . . 39
14.1. The Minimum of Metric . . . . . . . . . . . . . . . . . . 39
14.2. The Median of Metric . . . . . . . . . . . . . . . . . . . 39
14.3. The percentile of Metric . . . . . . . . . . . . . . . . . 39
14.4. The Failure Probability . . . . . . . . . . . . . . . . . 39
15. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 40
16. Security Considerations . . . . . . . . . . . . . . . . . . . 41
17. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42
18. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 43
19. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44
19.1. Normative References . . . . . . . . . . . . . . . . . . . 44
19.2. Informative References . . . . . . . . . . . . . . . . . . 44
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 46
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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 automates the provisioning of connections and drastically
reduces connection provision delay. As more and more services and
applications are seeking to use GMPLS controled 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 in the one hand be used to
depict the averaged performance of GMPLS implementations. On the
other hand, it can also be used in operational environments for
carriers to monitor the control plane operation in realtime. For
example, an new object can be added to GMPLS TE STD MIB [RFC4802]
such that the current and past control plane performance can be
monitored through network management systems. The extension of TE-
MIB to support the metrics defined is out the scope of this document.
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2. Overview of Performance Metrics
In this memo, to depict the dynamic LSP provisioning performance of a
GMPLS network, we define 3 performance metrics: unidirectional LSP
setup delay, bidirectional LSP setup delay, and LSP graceful release
delay. The latency of the LSP setup/release signal is similar to the
Round-trip Delay in IP networks. So we refer 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.
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3. A Singleton Definition for Single Unidirectional LSP Setup Delay
This part defines a metric for single unidirectional Label Switched
Path setup delay across a GMPLS network.
3.1. Motivation
Single unidirectional 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 incur higher overhead for the requesting application,
especially when the LSP duration 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 LSP setup delay variance has different impact on to applications.
Erratic variation in LSP setup delay makes it difficult to support
applications that has stringent setup delay requirement.
The measurement of single unidirectional LSP setup delay instead of
bidirectional LSP setup delay is motivated by the following factors:
o Some applications may only use unidirectional LSPs rather than
bidirectional ones. For example, content delivery services in
multicast method (IPTV) only use unidirectional LSPs.
3.2. Metric Name
single unidirectional LSP setup delay
3.3. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
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o T, a time when the setup is attempted
3.4. Metric Units
The value of single unidirectional LSP setup delay is either a real
number, or an undefined number of milliseconds.
3.5. Definition
The single unidirectional LSP setup delay from the ingress node ID0
to the 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 the ingress node ID0 received the last bit
of responding RESV message packet from the egress node ID1 at wire-
time T+dT in the unidirectional LSP setup case.
The single unidirectional LSP setup delay from the ingress node ID0
to the 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.
3.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of unidirectional 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
unidirectional 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 could be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move the micro mirrors. This
physical motion may take several milliseconds. But the common
electronic switches finish the nodal process within several
microseconds. So the unidirectional LSP setup delay varies
drastically from a network to another. In practice, the upper
bound should be chose carefully.
o If ingress node sends out the PATH message to set up LSP, but
never receive corresponding RESV message, unidirectional LSP setup
delay is deemed to be undefined.
o If ingress node sends out the PATH message to set up LSP but
receive PathErr message, unidirectional LSP setup delay is also
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deemed to be 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, etc.
3.7. 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 in 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 unidirectional LSP setup delay (T2 -T1) can be
computed.
o If the corresponding RESV message fails to arrive within a
reasonable period of time, the unidirectional 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
unidirectional LSP setup delay is deemed to be undefined.
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4. A Singleton Definition for multiple Unidirectional LSP Setup Delay
This part defines a metric for multiple unidirectional Label Switched
Paths setup delay across a GMPLS network.
4.1. Motivation
multiple unidirectional Label Switched Paths 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
4.2. Metric Name
multiple unidirectional LSPs setup delay
4.3. 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
4.4. Metric Units
The value of multiple unidirectional LSPs setup delay is either a
real number, or an undefined number of milliseconds.
4.5. Definition
Given Lambda_m and X, the multiple unidirectional 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
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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 unidirectional LSPs setup delay at T is undefined, means
that ingress node ID0 sends all the PATH messages toward the 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 the one or
more of the corresponding RESV messages within a reasonable period of
time.
4.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of multiple unidirectional 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 unidirectional 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 could be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move the micro mirrors. This
physical motion may take several milliseconds. But the common
electronic switches finish the nodal process within several
microseconds. So the multiple unidirectional LSP setup delay
varies drastically from a network to another. In practice, the
upper bound should be chose carefully.
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 unidirectional LSP setup delay is deemed to be
undefined.
o If ingress node sends out the PATH messages to set up the LSPs but
receives one or more PathErr messages, multiple unidirectional
LSPs setup delay is also deemed to be undefined. There are many
possible reasons for this case. For example, one of the PATH
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
carefully chosen such that in the one hand the control plane is
not overburdened.On the other hand, the arrival rate should also
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be large enough to meet the requirements of applications or
services.
4.7. 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, sends 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 arrives 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 unidirectional LSPs
setup delay (T2 -T1) can be computed.
o If one or more of the corresponding RESV messages fails to arrive
within a reasonable period of time, the multiple unidirectional
LSPs setup delay is deemed to be undefined. Note that the
'reasonable' threshold is a parameter of the methodology.
o If one of the corresponding response message is PathErr, the
multiple unidirectional LSPs setup delay is deemed to be
undefined.
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5. A Singleton Definition for Single Bidirectional LSP Setup Delay
GMPLS allows establishment of bi-directional symmetric LSPs (not of
asymmetric LSPs). This part defines a metric for single
bidirectional LSP setup delay across a GMPLS network.
5.1. Motivation
Single bidirectional 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
applications 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 to applications.
Erratic variation in LSP setup delay makes it difficult to support
applications that has stringent setup delay requirement.
The measurement of single bidirectional LSP setup delay instead of
unidirectional LSP setup delay is motivated by the following factors:
o Bidirectional LSPs are seen as a requirement for many GMPLS
networks. Its provisioning performance is important to
applications that generates bi-directional traffic.
5.2. Metric Name
Single bidirectional LSP setup delay
5.3. Metric Parameters
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o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T, a time when the setup is attempted
5.4. Metric Units
The value of single bidirectional LSP setup delay is either a real
number, or an undefined number of milliseconds.
5.5. Definition
For a real number dT, the single bidirectional 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 that packet at wire-time T+dT.
The single bidirectional 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.
5.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of single bidirectional 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 bidirectional 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 could be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move the micro mirrors. This
physical motion may take several milliseconds. But the common
electronic switches finish the nodal process within several
microseconds. So the bidirectional LSP setup delay varies
drastically from a network to another. In the process of
bidirectional LSP setup, if the downstream node overrides the
label suggested by the upstream node, the setup delay will also
increase obviously. Thus, in practice, the upper bound, should be
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chosen carefully.
o If the ingress node sends out the PATH message to set up the LSP,
but never receives the corresponding RESV message, single
bidirectional LSP setup delay is deemed to be undefined.
o If the ingress node sends out the PATH message to set up the LSP,
but receives PathErr message, single bidirectional LSP setup delay
is also deemed to be 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.
5.7. 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 in 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 bidirectional 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 bidirectional 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
bidirectional LSP setup delay is deemed to be undefined.
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6. A Singleton Definition for multiple Bidirectional LSPs Setup Delay
This part defines a metric for multiple bidirectional LSPs setup
delay across a GMPLS network.
6.1. Motivation
multiple Bidirectional 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
6.2. Metric Name
Multiple bidirectional LSPs setup delay
6.3. 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
6.4. Metric Units
The value of multiple bidirectional LSPs setup delay is either a real
number, or an undefined number of milliseconds.
6.5. Definition
Given Lambda_m and X, for a real number dT, the multiple
bidirectional 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
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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 packets at wire-
time T+dT
The multiple bidirectional 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 messages within a reasonable
period of time.
6.6. Discussion
The following issues are likely to come up in practice:
o The accuracy of multiple bidirectional 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
bidirectional 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 could be used. But GMPLS networks may
accommodate many kinds of devices. For example, some photonic
cross-connects (PXCs) have to move the micro mirrors. This
physical motion may take several milliseconds. But the common
electronic switches finish the nodal process within several
microseconds. So the multiple bidirectional LSPs setup delay
varies drastically from a network to another. In the process of
multiple bidirectional LSPs setup, if the downstream node
overrides the label suggested by the upstream node, the setup
delay will also increase obviously. Thus, in practice, the upper
bound should be chosen carefully.
o If the ingress node sends out the PATH messages to set up the
LSPs, but never receive all the corresponding RESV messages, the
multiple bidirectional LSPs setup delay is deemed to be undefined.
o If the ingress node sends out the PATH messages to set up the
LSPs, but receive one or more responding PathErr messages,the
multiple bidirectional LSPs setup delay is also deemed to be
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
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LSPs.
o The arrival rate of the poisson process Lambda_m should be
carefully chosen such that in the one hand the control plane is
not overburdened.On the other hand, the arrival rate should also
be large enough to meet the requirements of applications or
services.
6.7. 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, sends 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 arrives 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 bidirectional LSPs
setup delay (T2 -T1) can be computed.
o If one or more of the corresponding RESV messages fails to arrive
within a reasonable period of time, the multiple bidirectional
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 is PathErr,
the multiple bidirectional LSPs setup delay is deemed to be
undefined.
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7. 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. Memo in current
version has not taken forceful LSP release procedure into account.
7.1. 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 prefered in a GMPLS
controled network, particularly the optical networks. Since it
doesn't trigger restoration/protection, it is "alarm-free
connection deletion" in [RFC4208].
7.2. Metric Name
LSP graceful release delay
7.3. Metric Parameters
o ID0, the ingress LSR ID
o ID1, the egress LSR ID
o T, a time when the release is attemped
7.4. Metric Units
The value of LSP graceful release delay is either a real number, or
an undefined number of milliseconds.
7.5. Definition
There are two different LSP graceful release procedures, one is
initiated by the ingress node, and another is initiated by egress
node. The two procedures are depicted in the [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 setting the Reflect (R) and Delete (D) bits to egress node at
wire-time T, that egress node ID1 receives that packet, then
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immediately sends a RESV message including Admin Status Object with
the Delete (D) bit set back to ingress node. The 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 setting the Reflect (R) and Delete (D) bits, the
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, ingress
node does not receive that RESV packet, or) the 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. The 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,
ingress node does not send PathTear message packet in response or)
the egress node ID1 does not receive the PathTear within a reasonable
period of time.
7.6. 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;
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 could be used. But the upper bound should be
chosen carefully in practice;
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o In the first circumstance, if 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 never receive
corresponding RESV message, LSP graceful release delay is deemed
to be undefined. In the second circumstance, if egress node sends
out RESV message including Admin Status Object with the Reflect
(R) and Delete (D) bits set to initiate LSP graceful release, but
never receive corresponding PathTear message, LSP graceful release
delay is deemed to be undefined;
7.7. 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 in 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. Or, 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 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:
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 in the egress node when the RESV message
packet is sent towards the ingress node;
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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 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.
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8. A Definition for Samples of Single Unidirectional LSP Setup Delay
In Section 3, we define the singleton metric of Single unidirectional
LSP setup delay. Now we define how to get one particular sample of
Single unidirectional 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.
8.1. Metric Name
Single unidirectional LSP setup delay sample
8.2. 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 seconds
o Th, LSP holding time
o Td, the maximum waiting time for successful setup
8.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when setup is attemped
o dT, either a real number or an undefined number of milli-seconds.
8.4. 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 unidirectional 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.
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8.5. Discussion
The parameters lambda should be carefully chosen. If the rate is too
high, too frequent LSP setup/release procedure results in high
overhead in the control plane. In turn, the high overhead will
increase unidirectional 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 holding time of an
LSP is determined by actual traffic, hence in this case Th is not an
input parameter.
8.6. Methodologies
o The selection of specific times, using the specified Poisson
arrival process, and
o Set up the LSP as the methodology for the singleton unidirectional
LSP setup delay, and obtain the value of unidirectional LSP setup
delay
o Release the LSP after Th, and wait for the next Poisson arrival
process
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival process has arrived and
the LSP setup procedure is initiated. If there is resource
contention between the two LSPs, the LSP setup may fail.
8.7. Typical testing cases
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8.7.1. With No LSP in the Network
8.7.1.1. Motivation
Single unidirectional 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.
8.7.1.2. Methodologies
Make sure that there is no LSP in the network, and proceed with the
methodologies described in Section 8.6.
8.7.2. With a Number of LSPs in the Network
8.7.2.1. Motivation
Single unidirectional LSP setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considrable 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.
8.7.2.2. Methodologies
Setup the required number of LSPs, and wait until the network reaches
a stable state, then proceed with the methodologies described in
Section 8.6.
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9. A Definition for Samples of Multiple Unidirectional LSPs Setup Delay
In Section 4, we define the singleton metric of multiple
unidirectional LSPs setup delay. Now we define how to get one
particular sample of multiple unidirectional 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
Multiple unidirectional LSPs 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_m, a rate in the reciprocal seconds
o Lambda, a rate in the reciprocal seconds
o X, the number of LSPs to setup
o Td, the maximum waiting time for successful multiple
unidirectional LSPs setup
9.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when the first setup is attemped
o dT, either a real number or an undefined number of milli-seconds.
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 multiple unidirectional LSP
setup delay sample at this time. The value of the sample is the
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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.
9.5. Discussion
The parameter lambda is used as arrival rate of "bacth unidirectional
LSPs setup" operation. It regulates the interval in between each
batch operatoin. The parameter lambda_m is used within each batch
operation, as described in Section 4.
The parameters lambda and lambda_m should be carefully chosen. If
the rate is too high, too frequent LSP setup/release procedure
results in high overhead in the control plane. In turn, the high
overhead will increase unidirectional 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.
9.6. Methodologies
o The selection of specific times, using the specified Poisson
arrival process, and
o Set up the LSP as the methodology for the singleton multiple
unidirectional LSPs setup delay, and obtain the value of multiple
unidirectional LSPs setup delay
o Release the LSP after Th, and wait for the next Poisson arrival
process
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival process has arrived and
the LSP setup procedure is initiated. If there is resource
contention between the two LSP, the LSP setup may fail.
9.7. Typical testing cases
9.7.1. With No LSP in the Network
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9.7.1.1. Motivation
multiple unidirectional 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 LSPs traverse 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
multiple unidirectional LSPs setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considrable 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.
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..
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10. A Definition for Samples of Single Bidirectional LSP Setup Delay
In Section 5, we define the singleton metric of Single Bidirectional
LSP setup delay. Now we define how to get one particular sample of
Single Bidirectional 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
Single Bidirectional LSP setup delay sample with no LSP in the
network
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, a rate in the reciprocal seconds
o Th, LSP holding time
o Td, the maximum waiting time for successful setup
10.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when setup is attemped
o dT, either a real number or an undefined number of milli-seconds.
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
and less than or equal to Tf are then selected. At each of the times
in this process, we obtain the value of Bidirectional 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.
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10.5. Discussion
The parameters lambda should be carefully chosen. If the rate is too
high, too frequent LSP setup/release procedure results in high
overhead in the control plane. In turn, the high overhead will
increase Bidirectional 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 holding time of an
LSP is determined by actual traffic, hence in this case Th is not an
input parameter.
10.6. Methodologies
o The selection of specific times, using the specified Poisson
arrival process, and
o Set up the LSP as the methodology for the singleton bidirectional
LSP setup delay, and obtain the value of bidirectional LSP setup
delay
o Release the LSP after Th, and wait for the next Poisson arrival
process
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival process has arrived and
the LSP setup procedure is initiated. If there is resource
contention between the two LSP, the LSP setup may fail.
10.7. Typical testing cases
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10.7.1. With No LSP in the Network
10.7.1.1. Motivation
Single bidirectional 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.
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
Single bidirectional LSP setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considrable 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. .
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11. A Definition for Samples of Multiple Bidirectional LSPs Setup Delay
In Section 6, we define the singleton metric of multiple
bidirectional LSPs setup delay. Now we define how to get one
particular sample of multiple bidirectional 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
Multiple bidirectional LSPs setup delay sample
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_m, a rate in the reciprocal seconds
o Lambda, a rate in the reciprocal seconds
o X, the number of LSPs to setup
o Td, the maximum waiting time for successful multiple
unidirectional LSPs setup
11.3. Metric Units
A sequence of pairs; the elements of each pair are:
o T, a time when the first setup is attemped
o dT, either a real number or an undefined number of milli-seconds.
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 multiple unidirectional LSP
setup delay sample at this time. The value of the sample is the
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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.
11.5. Discussion
The parameter lambda is used as arrival rate of "bacth bidirectional
LSPs setup" operation. It regulates the interval in between each
batch operatoin. The parameter lambda_m is used within each batch
operation, as described in Section 6.
The parameters lambda and lambda_m should be carefully chosen. If
the rate is too high, too frequent LSP setup/release procedure
results in high overhead in the control plane. In turn, the high
overhead will increase unidirectional 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.
11.6. Methodologies
o The selection of specific times, using the specified Poisson
arrival process, and
o Set up the LSP as the methodology for the singleton multiple
bidirectional LSPs setup delay, and obtain the value of multiple
unidirectional LSPs setup delay
o Release the LSP after Th, and wait for the next Poisson arrival
process
Note that: it is possible that before the previous LSP release
procedure completes, the next Poisson arrival process has arrived and
the LSP setup procedure is initiated. If there is resource
contention between the two LSP, the LSP setup may fail.
11.7. Typical testing cases
11.7.1. With No LSP in the Network
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11.7.1.1. Motivation
multiple bidirectional 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 LSPs traverse 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 9.6.
11.7.2. With a Number of LSPs in the Network
11.7.2.1. Motivation
multiple bidirectional LSPs setup delay with a number of LSPs in the
network is important because it reflects the performance of an
operational network with considrable 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.
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..
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12. A Definition for Samples of LSP Graceful Release Delay
In Section 7, we define 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.
12.1. Metric Name
LSP graceful release 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, a rate in reciprocal seconds
o Td, the maximum waiting time for successful LSP release
12.3. 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 milli-seconds.
12.4. 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.
12.5. Discussion
The parameter lambda should be carefully chosen. If the rate is too
large, too frequent LSP setup/release procedure results in high
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overhead in the control plane. In turn, the high overhead will
increase unidirectional 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.
12.6. Methodologies
Generally the methodology would proceed as follows:
o Setup the LSP to be deleted
o The selection of specific 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 process
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13. Discussion for unsuccessful setup/release cases
As has been mentioned earlier, LSP setup/release 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 intermediat 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
deficiency.
Although not commonly seen, an LSP setup/release attemp may be
falsely carried out. for example, the setup/release request may be
targed to a wrong egress node. Although faulty results may have
totally different implications to the control plane, if compared with
failure cases, for the purpose of performance evaluation, it is still
reasonable to treat such results as unsuccessful cases. Thus the
unsuccessful cases include both failure and incorrect cases.
Once a sample of a particular metric, e.g, single unidirectional LSP
setup delay, is obtained, we can deduce the unsuccessful cases by
sorting out from the sample the <time, delay> pairs with undefined
delay value.
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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 are 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 is 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 are not counted in.
14.3. The percentile of Metric
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
unidirectional LSP setup delay 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. The Failure Probability
In the process of LSP setup/release, it may fail for some reason.
The failure probability is the ratio of the unsucessful times to the
total times. Note here that both failure and incorrect cases are
counted as unsucessful cases.
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15. Discussion
It is worthwhile to point out that:
o The unidirectional/bidirectional LSP setup delay is one ingress-
egress round trip time plus processing time. But in this
document, unidirectional/bidirectional 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
endpoint 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 [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 could be constructed with the use of suitable
signal generation test equipment. 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 Bidirectional LSPs may be setup using three way signalling,where
the initiate node will send a RESV_CONF message downsteam 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
bidirectional LSP setup delay defined in this document,does not
take the confirmation procedure in to account.
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16. Security Considerations
Samples of the metrics can be obtained in either active or passive
manners.
In the active manner, 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.
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17. IANA Considerations
This document makes no requests for IANA action.
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18. Acknowledgements
We wish to thank Dan Li, Fang Liu (Christine), Zafar Ali, Monique
Morrow, Al Morton, Adrian Farrel, Deborah Brungard, Thomas D. Nadeau
for their comments and helps.
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.
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19. References
19.1. Normative References
[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.
[RFC4802] Nadeau, T. and A. Farrel, "Generalized Multiprotocol Label
Switching (GMPLS) Traffic Engineering Management
Information Base", RFC 4802, February 2007.
19.2. Informative References
[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,
work in progress.
[RFC2330] Paxson, V., Almes, G., Mahdavi, J., and M. Mathis,
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"Framework for IP Performance Metrics", RFC 2330,
May 1998.
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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,MII.
Beijing 200240
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
Shanghai Jiao Tong University
800 Dongchuan Road
Shanghai 200240
CN
Phone: +86 21 3420 4596
Email: blithe@sjtu.edu.cn
Rajiv Papneja
Isocore
12359 Sunrise Valley Drive, STE 100
Reston, VA 20190
USA
Phone: +1 703 860 9273
Email: rpapneja@isocore.com
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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
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