Internet DRAFT - draft-banks-bmwg-issu-meth
draft-banks-bmwg-issu-meth
Benchmarking Methodology WG Sarah Banks
Internet Draft VSS Monitoring
Intended status: Informational Fernando Calabria
Expires: April 7, 2015 Cisco
Gery Czirjak
Ramdas Machat
Juniper
October 8, 2014
ISSU Benchmarking Methodology
draft-banks-bmwg-issu-meth-05
Abstract
Modern forwarding devices attempt to minimize any control and data
plane disruptions while performing planned software changes, by
implementing a technique commonly known as an In Service Software
Upgrade (ISSU).
This document specifies a set of common methodologies and procedures
designed to characterize the overall behavior of a Device Under Test
(DUT), subject to an ISSU event.
Status of this Memo
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Table of Contents
1. Introduction...................................................3
2. Conventions used in this document..............................4
3. Generic ISSU Process, phased approach..........................5
3.1. Software Download.........................................6
3.2. Software Staging..........................................6
3.3. Upgrade Run...............................................7
3.4. Upgrade Acceptance........................................7
4. Test Methodology...............................................8
4.1. Test Topology.............................................8
4.2. Load Model................................................9
5. ISSU Test Methodology.........................................10
5.1. Pre-ISSU recommended verifications.......................10
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5.2. Software Staging.........................................10
5.3. Upgrade Run..............................................11
5.4. Post ISSU verifications..................................12
5.5. ISSU under negative stimuli..............................13
6. ISSU Abort and Rollback.......................................14
7. Final Report - Data Presentation - Analysis...................14
7.1. Data collection considerations...........................16
8. Security Considerations.......................................16
9. IANA Considerations...........................................17
10. Conclusions..................................................17
11. References...................................................17
11.1. Normative References....................................17
11.2. Informative References..................................17
12. Acknowledgments..............................................17
1. Introduction
As required by most Service Provider (SP) network operators, ISSU
functionality has been implemented by modern forwarding devices to
upgrade or downgrade from one software version to another with a goal
of eliminating the downtime of the router and/or the outage of
service. However, It is noted that while most operators expect that
whiledesire such behavior as a elimination is the goal, minimal
downtime and/or degradation of service is often expected.
The ISSU operation may apply in terms of an atomic version change of
the entire system software or it may be applied in a more modular
sense such as for a patch or maintenance upgrade. The procedure
described herein may be used to verify either approach, as may be
supported by the vendor hardware and software.
In support of this document, a set of expectations for an ISSU
operation can be summarized as follows:
- The software is successfully migrated, from one version to a
successive version or vice versa.
- There are no control plane interruptions throughout the process.
That is, the upgrade/downgrade could be accomplished while the device
remains "in service". It is noted however, that most service
providers will still undertake such actions in a maintenance window
(even in redundant environments) to minimize any risk.
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- Interruptions to the forwarding plane are expected to be minimal
to none.
- The total time to accomplish the upgrade is minimized, again to
reduce potential network outage exposure (e.g. an external failure
event might impact the network as it operates with reduced
redundancy).
This document provides a set of procedures to characterize a given
forwarding device's ISSU behavior quantitatively, from the
perspective of meeting the above expectations.
Different hardware configurations may be expected to be benchmarked,
but a typical configuration for a forwarding device that supports
ISSU consists of at least one pair of Routing Processors (RP's) that
operate in a redundant fashion, and single or multiple Forwarding
Engines (Line Cards) that may or may not be redundant, as well as
fabric cards or other components as applicable. However, this does
not preclude the possibility that a device in question can perform
ISSU functions through the operation of independent process
components, which may be upgraded without impact to the overall
operation of the device. As an example, perhaps the software module
involved in SNMP functions can be upgraded without impacting other
operations.
The concept of a multi-chassis deployment may also be characterized
by the current set of proposed methodologies, but the implementation
specific details (i.e. process placement and others) are beyond the
scope of the current document.
Since most modern forwarding devices, where ISSU would be applicable,
do consist of redundant RP's and hardware-separated control plane and
data plane functionality, this document will focus on methodologies
which would be directly applicable to those platforms. It is
anticipated that the concepts and approaches described herein may be
readily extended to accommodate other device architectures as well.
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 RFC-2119 [RFC2119].
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In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
In this document, the characters ">>" preceding an indented line(s)
indicates a compliance requirement statement using the key words
listed above. This convention aids reviewers in quickly identifying
or finding the explicit compliance requirements of this RFC.
3. Generic ISSU Process, phased approach
ISSU may be viewed as the behavior of a device when exposed to a
planned change in its software functionality. This may mean changes
to the core operating system, separate processes or daemons or even
of firmware logic in programmable hardware devices (e.g. CPLD/FPGA).
The goal of an ISSU implementation is to permit such actions with
minimal or no disruption to the primary operation of the device in
question.
ISSU may be user initiated through direct interaction with the device
or activated through some automated process on a management system or
even on the device itself. For the purposes of this document, we will
focus on the model where the ISSU action is initiated by direct user
intervention.
The ISSU process can be viewed as a series of different phases or
activities, as defined below. For each of these phases, the test
operator MUST record the outcome as well as any relevant observations
(defined further in the present document). Note that, a given vendor
implementation may or may not permit the abortion of the in-progress
ISSU at particular stages. There may also be certain restrictions as
to ISSU availability given certain functional configurations (for
example, ISSU in the presence of Bidirectional Failure Detection
(BFD) [RFC 5880] may not be supported. It is incumbent upon the test
operator to ensure that the DUT is appropriately configured to
provide the appropriate test environment as needed. As with any
properly orchestrated test effort, the test plan document should
reflect these and other relevant details and SHOULD be written with
close attention to the expected production-operating environment. The
combined analysis of the results of each phase will characterize the
overall ISSU process with the main goal of being able to identify and
quantify any disruption in service (from the data and control plane
perspective) allowing operators to plan their maintenance activities
with greater precision.
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The generic ISSU process can be viewed as a series of the following
phases:
3.1. Software Download
In this first phase, the requested software package may be downloaded
to the router and is typically stored onto a device. The downloading
of software may be performed automatically by the device as part of
the upgrade process, or it may be initiated separately. Such
separation allows an administrator to download the new code inside or
outside of a maintenance window; it is anticipated that downloading
new code and saving it to disk on the router will not impact
operations. In the case where the software can be downloaded outside
of the actual upgrade process, the administrator SHOULD do so;
downloading software can skew timing results based on factors that
are often not comparative in nature. Internal compatibility
verification may be performed by the software running on the DUT, to
verify the checksum of the files downloaded as well as any other
pertinent checks. Depending upon vendor implementation, these
mechanisms may extend to include verification that the downloaded
module(s) meet a set of identified pre-requisites such as hardware or
firmware compatibility or minimum software requirements. Where such
mechanisms are made available by the product, they should be
verified, by the tester, with the perspective of avoiding operational
issues in production. Verification should include both positive
verification (ensuring that an ISSU action should be permitted) as
well as negative tests (creation of scenarios where the verification
mechanisms would report exceptions).
3.2. Software Staging
In this second phase, the requested software package is loaded into
the pertinent components of a given forwarding device (typically the
RP in standby state). Internal compatibility verification may be
performed by the software running on the DUT, as part of the upgrade
process itself, to verify the checksum of the files downloaded as
well as any other pertinent checks. Depending upon vendor
implementation, these mechanisms may extend to include verification
that the downloaded module(s) meet a set of identified pre-requisites
such as hardware or firmware compatibility or minimum software
requirements. Where such mechanisms are made available by the
product, they should be verified, by the tester, with the perspective
of avoiding operational issues in production. In this case, the
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execution of these checks is within scope of the upgrade time, and
SHOULD be included in the testing results. Once the new software is
downloaded to the pertinent components of the DUT, the upgrade begins
and the DUT begins to prepare itself for upgrade. Depending on the
vendor implementation, it is expected that redundant hardware pieces
within the DUT are upgraded, including the backup or secondary RP.
3.3. Upgrade Run
In this phase, a switchover of RPs may take place, where one RP is
now upgraded with the new version of software. More importantly, the
"Upgrade Run" phase is where the internal changes made to information
and state stored on the router, on disk and in memory, are either
migrated to the "new" version of code, or transformed/rebuilt to meet
the standards of the new version of code, and pushed onto the
appropriate pieces of hardware. It is within this phase that any
outage(s) on the control or forwarding plane MAY be expected to be
observed.
This is the critical phase of the ISSU, where the control plane
should not be impacted and any interruptions to the forwarding plane
should be minimal to none.
For some implementations, the above two steps may be concatenated
into one monolithic operation. In such case, the calculation of the
respective ISSU time intervals may need to be adapted accordingly. If
any control or data plane interruptions occur, it is expected to be
observed and recorded within this stage.
3.4. Upgrade Acceptance
In this phase, the new version of software MUST be running in all the
physical nodes of the logical forwarding device. (RP's and LC's as
applicable). At this point, configuration control is returned to the
operator and normal device operation i.e. outside of ISSU-oriented
operation, is resumed.
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4. Test Methodology
As stated by http://tools.ietf.org/wg/bmwg/draft-ietf-bmwg-2544-as/
(when it becomes an RFC) The Test Topology Setup must be part of an
ITE (Isolated Test Environment)
The reporting of results MUST take into account the repeatability
considerations from Section 4 of [RFC2544]. It is RECOMMENDED to
perform multiple trials and report average results. The results are
reported in a simple statement including the measured frame loss and
ISSU impact times.
4.1. Test Topology
The hardware configuration of the DUT (Device Under test) MUST be
identical to the one expected to be or currently deployed in
production in order for the benchmark to have relevance. This would
include the number of RP's, hardware version, memory and initial
software release, any common chassis components, such as fabric
hardware in the case of a fabric-switching platform and the specific
LC's (version, memory, interfaces type, rate etc.)
For the Control and Data plane, differing configuration approaches
MAY be utilized. The recommended approach relies on "mimicking" the
existing production data and control plane information, in order to
emulate all the necessary Layer1 through Layer3 and, if appropriate,
upper layer characteristics of the network, as well as end to end
traffic/communication pairs. In other words, design a representative
load model of the production environment and deploy a collapsed
topology utilizing test tools and/or external devices, where the DUT
will be tested. Note that, the negative impact of ISSU operations is
likely to impact scaled, dynamic topologies to a greater extent than
simpler, static environments. As such, this methodology is advised
for most test scenarios.
The second, more simplistic approach is to deploy an ITE "Isolated
Testing Environment" as described in some of the existing standards
for benchmarking methodologies (e.g. RFC2544/RFC6815) in which end-
points are "directly" connected to the DUT. In this manner control
plane information is kept to a minimum (only connected interfaces)
and only a basic data plane of sources and destinations is applied.
If this methodology is selected, care must be taken to understand
that the systemic behavior of the ITE may not be identical to that
experienced by a device in a production network role. That is,
control plane validation may be minimal to none if this methodology
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is employed. It may be possible to perform some degree of data plane
validation with this approach.
4.2. Load Model
In consideration of the defined test topology, a load model must be
developed to exercise the DUT while the ISSU event is introduced.
This applied load should be defined in such a manner as to provide a
granular, repeatable verification of the ISSU impact on transit
traffic. Sufficient traffic load (rate) should be applied to permit
timing extrapolations at a minimum granularity of 100 milliseconds
e.g. 100Mbps for a 10Gbps interface. The use of steady traffic
streams rather than bursty loads is preferred to simplify analysis.
The traffic should be patterned to provide a broad range of source
and destination pairs, which resolve to a variety of FIB (forwarding
information base) prefix lengths. If the production network
environment includes multicast traffic or VPN's (L2, L3 or IPSec) it
is critical to include these in the model.
For mixed protocol environments (e.g. IPv4 and IPv6), frames SHOULD
be distributed between the different protocols. The distribution
SHOULD approximate the network conditions of deployment. In all
cases, the details of the mixed protocol distribution MUST be
included in the reporting.
The feature, protocol timing and other relevant configurations
should be matched to the expected production environment. Deviations
from the production templates may be deemed necessary by the test
operator (for example, certain features may not support ISSU or the
test bed may not be able to accommodate such). However, the impact
of any such divergence should be clearly understood and the
differences MUST be recorded in the results documentation.
It is recommended that an NMS system be deployed, preferably similar
to that utilized in production. This will allow for monitoring of
the DUT while it is being tested both in terms of supporting the
system resource impact analysis as well as from the perspective of
detecting interference with non-transit (management) traffic as a
result of the ISSU operation. Additionally, a DUT management session
other than snmp-based, typical of usage in production, should be
established to the DUT and monitored for any disruption.
It is suggested that the actual test exercise be managed utilizing
direct console access to the DUT, if at all possible to avoid the
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possibility that a network interruption impairs execution of the
test exercise.
All in all, the load model should attempt to simulate the production
network environment to the greatest extent possible in order to
maximize the applicability of the results generated.
5. ISSU Test Methodology
As previously described, for the purposes of this test document, the
ISSU process is divided into three main phases. The following
methodology assumes that a suitable test topology has been
constructed per section 4. A description of the methodology to be
applied for each of the above phases follows:
5.1. Pre-ISSU recommended verifications
Verify that enough hardware and software resources are available to
complete the Load operation (enough disk space).
Verify that the redundancy states between RPs and other nodes are
as expected (e.g. redundancy on, RP's synchronized).
Verify that the device, if running NSR capable routing protocols,
is in a "ready" state; that is, that the sync between RPs is
complete and the system is ready for failover, if necessary.
Gather a configuration snapshot of the device and all of its
applicable components.
Verify that the node is operating in a "steady" state (that is, no
critical or maintenance function is being currently performed).
Note any other operational characteristics that the tester may deem
applicable to the specific implementation deployed.
5.2. Software Staging
Establish all relevant protocol adjacencies and stabilize routing
within the test topology. In particular, ensure that the scaled
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levels of the dynamic protocols are dimensioned as specified by the
test topology plan.
Clear relevant logs and interface counters to simplify analysis. If
possible, set logging timestamps to a highly granular mode. If the
topology includes management systems, ensure that the appropriate
polling levels have been applied, sessions established and that the
responses are per expectation.
Apply the traffic loads as specified in the load model previously
developed for this exercise.
Document an operational baseline for the test bed with relevant
data supporting the above steps (include all relevant load
characteristics of interest in the topology e.g. routing load,
traffic volumes, memory and CPU utilization)
Note the start time (T0) and begin the code change process
utilizing the appropriate mechanisms as expected to be used in
production (e.g. active download with TFTP/FTP/SCP/etc. or direct
install from local or external storage facility). In order to
ensure that ISSU process timings are not skewed by the lack of a
network wide synchronization source, the use of a network NTP
source is encouraged.
Take note of any logging information and command line interface
(CLI) prompts as needed (this detail will be vendor-specific).
Respond to any DUT prompts in a timely manner.
Monitor the DUT for the reload of secondary RP to the new software
level. Once the secondary has stabilized on the new code, note the
completion time. The duration of these steps will be logged as
"T1".
Review system logs for any anomalies, check that relevant dynamic
protocols have remained stable and note traffic loss if any. Verify
that deployed management systems have not identified any unexpected
behavior.
5.3. Upgrade Run
The following assumes that the software load step and upgrade step
are discretely controllable. If not, maintain the afore-mentioned
timer and monitor for completion of the ISSU as described below.
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Note the start time and initiate the actual upgrade procedure.
Monitor the operation of the secondary route processor while it
initializes with the new software and assumes mastership of the
DUT.
At this point, pay particular attention to any indications of
control plane disruption, traffic impact or other anomalous
behavior. Once the DUT has converged upon the new code and returned
to normal operation note the completion time and log the duration
of this step as T2.
Review the syslog data in the DUT and neighboring devices for any
behavior, which would be disruptive in a production environment
(linecard reloads, control plane flaps etc.). Examine the traffic
generators for any indication of traffic loss over this interval.
If the Test Set reported any traffic loss, note the number of
frames lost as "TP_frames". If the test set also provides outage
duration, note this as TP_time (alternatively this may be
calculated as TP/offered pps (packets per second) load).
Verify the DUT status observations as per any NMS systems managing
the DUT and its neighboring devices. Document the observed CPU and
memory statistics both during the ISSU upgrade event and after and
ensure that memory and CPU have returned to an expected (previously
baselined) level.
5.4. Post ISSU verifications
The following describes a set of post-ISSU verification tasks that
are not directly part of the ISSU process, but are recommended for
execution in order to validate a successful upgrade:
. Configuration delta analysis
o Examine the post-ISSU configurations to determine if any
changes have occurred either through process error or due to
differences in the implementation of the upgraded code.
. Exhaustive control plane analysis
o Review the details of the RIB and FIB to assess whether any
unexpected changes have been introduced in the forwarding
paths.
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. Verify that both RPs are up and that the redundancy mechanism for
the control plane is enabled and fully synchronized.
. Verify that no control plane (protocol) events or flaps were
detected.
. Verify that no L1 and or L2 interface flaps were observed.
. Document the hitless operation or presence of an outage based
upon the counter values provided by the Test Set.
5.5. ISSU under negative stimuli
As an OPTIONAL Test Case, the operator may want to perform an ISSU
test while the DUT is under stress by introducing route churn to
any or all of the involved phases of the ISSU process.
One approach relies on the operator to gather statistical
information from the production environment and determine a
specific number of routes to flap every 'fixed' or 'variable'
interval. Alternatively, the operator may wish to simply pre-select
a fixed number of prefixes to flap. As an example, an operator may
decide to flap 1% of all the BGP routes every minute and restore
them 1 minute afterwards. The tester may wish to apply this
negative stimulus throughout the entire ISSU process or most
importantly, during the run phase.
It is important to ensure that these routes, which are introduced
solely for stress proposes, MUST not overlap the ones (per the Load
Model) specifically leveraged to calculate the TP (recorded
outage). Furthermore, there SHOULD NOT be 'operator induced'
control plane - protocol adjacency flaps for the duration of the
test process as it may adversely affect the characterization of the
entire test exercise. For example, triggering IGP adjacency events
may force re-computation of underlying routing tables with
attendant impact to the perceived ISSU timings. While not
recommended, if such trigger events are desired by the test
operator, care should be taken to avoid the introduction of
unexpected anomalies within the test harness.
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6. ISSU Abort and Rollback
Where a vendor provides such support, the ISSU process could be
aborted for any reason by the operator. However, the end results and
behavior may depend on the specific phase where the process was
aborted. While this is implementation dependent, as a general
recommendation, if the process is aborted during the "Software
Download" or "Software Staging" phases, no impact to service or
device functionality should be observed. In contrast, if the process
is aborted during the "Upgrade Run" or "Upgrade Accept" phases, the
system may reload and revert back to the previous software release
and as such, this operation may be service affecting.
Where vendor support is available, the abort/rollback functionality
should be verified and the impact, if any, quantified generally
following the procedures provided above.
7. Final Report - Data Presentation - Analysis
All ISSU impact results are summarized in a simple statement
describing the "ISSU Disruption Impact" including the measured frame
loss and impact time, where impact time is defined as the time frame
determined per the TP reported outage. These are considered to be
the primary data points of interest.
However, the entire ISSU operational impact should also be
considered in support of planning for maintenance and as such,
additional reporting points are included.
Software download/secondary update T1
Upgrade/Run T2
ISSU Traffic Disruption (Frame Loss) TP_frames
ISSU Traffic Impact Time (milliseconds) TP Time
ISSU Housekeeping Interval T3
(Time for both RP's up on new code
and fully synced - Redundancy restored)
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Total ISSU Maintenance Window T4 (sum of T1+T2+T3)
The results reporting MUST provide the following information:
. DUT hardware and software detail
. Test Topology definition and diagram (especially as related
to the ISSU operation)
. Load Model description including protocol mixes and any
divergence from the production environment
. Time Results as per above
. Anomalies Observed during ISSU
. Anomalies Observed in post-ISSU analysis
It is RECOMMENDED that the following parameters be reported in these
units:
Parameter Units or Examples
---------------------------------------------------------------
Traffic Load Frames per second and bits per
Second
Disruption (average) Frames
Impact Time (average) Milliseconds
Number of trials Integer count
Protocols IPv4, IPv6, MPLS, etc.
Frame Size Octets
Port Media Ethernet, Gigabit Ethernet (GbE),
Packet over SONET (POS), etc.
Port Speed 10 Gbps, 1 Gbps, 100 Mbps, etc.
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Interface Encap. Ethernet, Ethernet VLAN,
PPP, High-Level Data Link Control
(HDLC),etc.
Number of Prefixes
flapped (ON Interval)
(Optional) # of prefixes / Time (minutes)
Number of Prefixes
flapped (OFF Interval) # of prefixes / Time (minutes)
(Optional)
Document any configuration deltas, which are observed after the ISSU
upgrade has taken effect. Note differences, which are driven by
changes in the patch or release level as well as items, which are
aberrant changes due to software faults. In either of these cases,
any unexpected behavioral changes should be analyzed and a
determination made as to the impact of the change (be it functional
variances or operational impacts to existing scripts or management
mechanisms.
7.1. Data collection considerations
When a DUT is undergoing an ISSU operation, it's worth noting that
the DUT's data collection and reporting of data, such as counters,
interface statistics, log messages, etc., might not be accurate. As
such, one SHOULD NOT rely on the DUTs data collection methods, but
rather, SHOULD use the test tools and equipment to collect data used
for reporting in Section 7. Care and consideration should be paid in
testing or adding new test cases, such that the desired data can be
collected from the test tools themselves, or other external
equipment, outside of the DUT itself.
8. Security Considerations
None at this time.
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9. IANA Considerations
None at this time.
10. Conclusions
None at this time.
11. References
11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, Internet Mail Consortium and
Demon Internet Ltd., November 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.
11.2. Informative References
[3] Faber, T., Touch, J. and W. Yue, "The TIME-WAIT state in TCP
and Its Effect on Busy Servers", Proc. Infocom 1999 pp. 1573-
1583.
[Fab1999] Faber, T., Touch, J. and W. Yue, "The TIME-WAIT state in
TCP and Its Effect on Busy Servers", Proc. Infocom 1999 pp.
1573-1583.
[RFC2234]Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.
12. Acknowledgments
The authors wish to thanks Vibin Thomas for his valued review and
feedback.
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Copyright (c) 2014 IETF Trust and the persons identified as authors
of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
o Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
o Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
o Neither the name of Internet Society, IETF or IETF Trust, nor the
names of specific contributors, may be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Authors' Addresses
Sarah Banks
VSS Monitoring
Email: sbanks@encrypted.net
Fernando Calabria
Cisco Systems
Email: fcalabri@cisco.com
Gery Czirjak
Juniper Networks
Email: gczirjak@juniper.net
Ramdas Machat
Juniper Networks
Email: rmachat@juniper.net
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