Internet Engineering Task Force (IETF) R. Papneja
Request for Comments: 6894 Huawei Technologies
Category: Informational S. Vapiwala
ISSN: 2070-1721 J. Karthik
Cisco Systems
S. Poretsky
Allot Communications
S. Rao
Qwest Communications
JL. Le Roux
France Telecom
March 2013
Methodology for Benchmarking MPLS Traffic Engineered (MPLS-TE)
Fast Reroute Protection
Abstract
This document describes the methodology for benchmarking MPLS Fast
Reroute (FRR) protection mechanisms for link and node protection.
This document provides test methodologies and testbed setup for
measuring failover times of Fast Reroute techniques while considering
factors (such as underlying links) that might impact
recovery times for real-time applications bound to MPLS Traffic
Engineered (MPLS-TE) tunnels.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any
errata, and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6894.
Papneja, et al. Informational [Page 1]RFC 6894 MPLS Protection Mechanisms March 2013
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than English.
Table of Contents
1. Introduction ....................................................3
2. Document Scope ..................................................5
3. Existing Definitions and Requirements ...........................5
4. General Reference Topology ......................................6
5. Test Considerations .............................................7
5.1. Failover Events ............................................7
5.2. Failure Detection ..........................................8
5.3. Use of Data Traffic for MPLS Protection Benchmarking .......8
5.4. LSP and Route Scaling ......................................9
5.5. Selection of IGP ...........................................9
5.6. Restoration and Reversion ..................................9
5.7. Offered Load ...............................................9
5.8. Tester Capabilities .......................................10
5.9. Failover Time Measurement Methods .........................10
6. Reference Test Setup ...........................................11
6.1. Link Protection ...........................................12
6.1.1. Link Protection: 1-Hop Primary (from PLR)
and 1-Hop Backup Tail-End Tunnels ..................12
Papneja, et al. Informational [Page 2]RFC 6894 MPLS Protection Mechanisms March 2013
6.1.2. Link Protection: 1-Hop Primary (from PLR)
and 2-Hop Backup Tail-End Tunnels ..................13
6.1.3. Link Protection: 2-Hop (or More) Primary (from PLR)
and 1-Hop Backup Tail-End Tunnels ..................14
6.1.4. Link Protection: 2-Hop (or More) Primary (from PLR)
and 2-Hop Backup Tail-End Tunnels ..................15
6.2. Node Protection ...........................................16
6.2.1. Node Protection: 2-Hop Primary (from PLR)
and 1-Hop Backup Tail-End Tunnels ..................16
6.2.2. Node Protection: 2-Hop Primary (from PLR)
and 2-Hop Backup Tail-End Tunnels ..................17
6.2.3. Node Protection: 3-Hop (or More) Primary (from PLR)
and 1-Hop Backup Tail-End Tunnels ..................18
6.2.4. Node Protection: 3-Hop (or More) Primary (from PLR)
and 2-Hop Backup Tail-End Tunnels ..................19
7. Test Methodology ...............................................19
7.1. MPLS-FRR Forwarding Performance ...........................20
7.1.1. Head-End PLR Forwarding Performance ................20
7.1.2. Midpoint PLR Forwarding Performance ................21
7.2. Head-End PLR with Link Failure ............................22
7.3. Midpoint PLR with Link Failure ............................24
7.4. Head-End PLR with Node Failure ............................25
7.5. Midpoint PLR with Node Failure ............................26
8. Reporting Format ...............................................27
9. Security Considerations ........................................29
10. Acknowledgements ..............................................29
11. References ....................................................29
11.1. Normative References .....................................29
11.2. Informative References ...................................30
Appendix A. Fast Reroute Scalability Table ........................31
Appendix B. Abbreviations .........................................34
1. Introduction
This document describes the methodology for benchmarking MPLS Fast
Reroute (FRR) protection mechanisms. This document uses much of the
terminology defined in [RFC6414].
Protection mechanisms provide recovery of client services from a
planned or an unplanned link or node failure. MPLS-FRR protection
mechanisms are generally deployed in a network infrastructure where
MPLS is used for the provisioning of point-to-point traffic
engineered tunnels (tunnel). MPLS-FRR protection mechanisms aim to
reduce the service disruption period by minimizing recovery time from
most common failures.
Papneja, et al. Informational [Page 3]RFC 6894 MPLS Protection Mechanisms March 2013
Network elements from different manufacturers behave differently to
network failures, which impacts the network's ability and performance
for failure recovery. Therefore, it becomes imperative for service
providers to have a common benchmark to understand the performance
behaviors of network elements.
There are two factors impacting service availability: frequency of
failures and duration for which the failures persist. Failures can
be classified further into two types: correlated and uncorrelated.
Correlated and uncorrelated failures may be planned or unplanned.
Planned failures are generally predictable. Network implementations
should be able to handle both planned and unplanned failures and
recover gracefully within a time frame to maintain service assurance.
Hence, failover recovery time is one of the most important benchmarks
that a service provider considers in choosing the building blocks for
their network infrastructure.
A correlated failure is a result of the occurrence of two or more
failures. A typical example is failure of a logical resource (e.g.,
Layer-2 (L2) links) due to a dependency on a common physical resource
(e.g., common conduit) that fails. Within the context of MPLS
protection mechanisms, failures that arise due to Shared Risk Link
Groups (SRLGs) [RFC4202] can be considered as correlated failures.
MPLS-FRR [RFC4090] allows for the possibility that the Label Switched
Paths (LSPs) can be reoptimized in the minutes following failover.
IP traffic would be rerouted according to the preferred path for the
post-failure topology. Thus, MPLS-FRR may include additional steps
following the occurrence of the failure detection and failover event
[RFC6414].
(1) Failover Event - Primary path (working path) fails
(2) Failure Detection - Failover event is detected
(3a) Failover - Working path switched to backup path
(3b) Reoptimization of working path (possible change from backup
path)
(4) Restoration (see Section 3.3.5 of [RFC6414])
(5) Reversion (see Section 3.3.6 of [RFC6414])
Papneja, et al. Informational [Page 4]RFC 6894 MPLS Protection Mechanisms March 2013
2. Document Scope
This document provides detailed test cases along with different
topologies and scenarios that should be considered to effectively
benchmark MPLS-FRR protection mechanisms and failover times on the
data plane. Different failover events and scaling considerations are
also provided in this document.
All benchmarking test cases defined in this document apply to
facility backup [RFC4090]. The test cases cover a set of interesting
failure scenarios and the associated procedures benchmark the
performance of the Device Under Test (DUT) to recover from failures.
Data-plane traffic is used to benchmark failover times. Testing
scenarios related to MPLS-TE protection mechanisms when applied to
MPLS Transport Profile and IP fast reroute applied to MPLS networks
were not considered and are outside the scope of this document.
However, the test setups considered for MPLS-based L3 and L2 services
consider LDP over MPLS RSVP-TE configurations.
Benchmarking of correlated failures is outside the scope of this
document. Detection using Bidirectional Forwarding Detection (BFD)
is outside the scope of this document, but it is mentioned in
discussion sections.
The performance of the control plane is outside the scope of this
document.
As described above, MPLS-FRR may include a reoptimization of the
working path, with possible packet transfer impairments.
Characterization of reoptimization is beyond the scope of this memo.
3. Existing Definitions and Requirements
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 BCP 14 [RFC2119].
While [RFC2119] defines the use of these key words primarily for
Standards Track documents, this Informational document uses some of
these key words.
The reader is assumed to be familiar with the commonly used MPLS
terminology, some of which is defined in [RFC4090].
This document uses much of the terminology defined in [RFC6414].
This document also uses existing terminology defined in other BMWG
documents [RFC1242] [RFC2285] [RFC4689]. Appendix B provides
abbreviations used in the document.
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RFC 6894 MPLS Protection Mechanisms March 2013
4. General Reference Topology
Figure 1 illustrates the general reference topology. It shows the
basic reference testbed and is applicable to all the test cases
defined in this document. The Tester is comprised of a Traffic
Generator (TG) and Traffic Analyzer (TA) and Emulator. A Tester is
connected to the test network and, depending upon the test case, the
DUT could vary. The Tester sends and receives IP traffic to the
tunnel ingress and performs signaling protocol emulation to simulate
real network scenarios in a lab environment. The Tester may also
support MPLS-TE signaling to act as the ingress node to the MPLS
tunnel. The lines in figures represent physical connections.
+---------------------------+
| +------------|---------------+
| | | |
| | | |
+--------+ +--------+ +--------+ +--------+ +--------+
TG--| R1 |-----| R2 |----| R3 | | R4 | | R5 |
| |-----| |----| |----| |---| |
+--------+ +--------+ +--------+ +--------+ +--------+
| | | | |
| | | | |
| +--------+ | | TA
+---------| R6 |---------+ |
| |----------------------+
+--------+
Figure 1
The tester MUST record the number of lost, duplicate, and out-of-
order packets. It should further record arrival and departure times
so that failover time, Additive Latency, and Reversion Time can be
measured. The tester may be a single device or a test system
emulating all the different roles along a primary or backup path.
The label stack is dependent on the following three entities:
(1) Type of protection (Link versus Node)
(2) Number of remaining hops of the primary tunnel from the Point of
Local Repair (PLR) [RFC6414]
(3) Number of remaining hops of the backup tunnel from the PLR
Due to this dependency, it is RECOMMENDED that the benchmarking of
failover times be performed on all the topologies provided in Section
6.
Papneja, et al. Informational [Page 6]RFC 6894 MPLS Protection Mechanisms March 2013
5. Test Considerations
This section discusses the fundamentals of MPLS Protection testing:
(1) The types of network events that cause failover (Section 5.1)
(2) Indications for failover (Section 5.2)
(3) The use of data traffic (Section 5.3)
(4) Label Switched Path Scaling (Section 5.4)
(5) IGP Selection (Section 5.5)
(6) Reversion of LSP (Section 5.6)
(7) Traffic generation (Section 5.7)
5.1. Failover Events
The failover to the backup tunnel is primarily triggered by either
link or node failures observed downstream of the Point of Local
Repair (PLR). The failure events [RFC6414] are listed below.
Link Failure Events
- Interface Shutdown on PLR side with physical/link alarm
- Interface Shutdown on remote side with physical/link alarm
- Interface Shutdown on PLR side with RSVP hello enabled
- Interface Shutdown on remote side with RSVP hello enabled
- Interface Shutdown on PLR side with BFD
- Interface Shutdown on remote side with BFD
- Fiber Pull on the PLR side (both Transmit (TX) and Receive (RX)
or just the TX)
- Fiber Pull on the remote side (both TX and RX or just the RX)
- Online Insertion and Removal (OIR) on PLR side
- OIR on remote side
- Sub-interface failure on PLR side (e.g., shutting down of a
VLAN)
- Sub-interface failure on remote side
- Parent interface shutdown on PLR side (an interface bearing
multiple sub-interfaces)
- Parent interface shutdown on remote side
Node Failure Events
- A System reload initiated by either a graceful shutdown or a
power failure
- A system crash due to a software failure or an assert
Papneja, et al. Informational [Page 7]RFC 6894 MPLS Protection Mechanisms March 2013
5.2. Failure Detection
Link failure detection [RFC6414] time depends on the link type and
failure detection protocols running. For Synchronous Optical Network
(SONET) / Synchronous Digital Hierarchy (SDH), the alarm type (such
as LOS, AIS, or RDI) can be used. Other link types have L2 alarms,
but they may not provide a short enough failure detection time.
Ethernet-based links enabled with MPLS/IP do not have L2 failure
indicators; therefore, they rely on L3 signaling for failure
detection. However, for directly connected devices, remote fault
indication in the ethernet auto-negotiation scheme could be
considered as a type of L2 link failure indicator.
MPLS has different failure detection techniques, such as BFD, or use
of RSVP hellos. These methods can be used for the L3 failure
indicators required by ethernet-based links or for some other non-
ethernet-based links to help improve failure detection time.
However, these fast failure detection mechanisms are out of scope.
The test procedures in this document can be used for local failure or
remote failure scenarios for comprehensive benchmarking and to
evaluate failover performance independent of the failure detection
techniques.
5.3. Use of Data Traffic for MPLS Protection Benchmarking
Currently, end customers use packet loss as a key metric for failover
time [RFC6414]. Failover Packet Loss [RFC6414] is an externally
observable event and has a direct impact on application performance.
MPLS protection is expected to minimize packet loss in the event of a
failure. For this reason, it is important to develop a standard
router benchmarking methodology for measuring MPLS protection that
uses packet loss as a metric. At a known rate of forwarding, packet
loss can be measured and the failover time can be determined.
Measurement of control-plane signaling to establish backup paths is
not enough to verify failover. Failover is best determined when
packets are actually traversing the backup path.
An additional benefit of using packet loss for calculation of
failover time is that it allows use of a black-box test environment.
Data traffic is offered at line-rate to the DUT, an emulated network
failure event is forced to occur, and packet loss is externally
measured to calculate the convergence time. This setup is
independent of the DUT architecture.
In addition, this methodology considers the packets in error and
duplicate packets [RFC4689] that could have been generated during the
failover process. The methodologies consider lost, out-of-order
Papneja, et al. Informational [Page 8]
RFC 6894 MPLS Protection Mechanisms March 2013
[RFC4689], and duplicate packets to be impaired packets that
contribute to the failover time.
5.4. LSP and Route Scaling
Failover time performance may vary with the number of established
primary and backup tunnel LSPs and installed routes. However, the
procedure outlined here should be used for any number of LSPs (L) and
any number of routes protected by the PLR (R). The values of L and R
must be recorded.
5.5. Selection of IGP
The underlying IGP could be ISIS-TE or OSPF-TE for the methodology
proposed here. See [RFC6412] for IGP options to consider and report.
5.6. Restoration and Reversion
Path restoration [RFC6414] provides a method to restore an alternate
primary LSP upon failure and to switch traffic from the backup path
to the restored primary path (reversion). In MPLS-FRR, reversion
[RFC6414] can be implemented as Global Reversion or Local Reversion.
It is important to include restoration and reversion as a step in
each test case to measure the amount of packet loss, out-of-order
packets, or duplicate packets that are produced.
Note: In addition to restoration and reversion, reoptimization can
take place while the failure is still not recovered but it depends on
the user configuration and reoptimization timers.
5.7. Offered Load
It is suggested that there be three or more traffic streams as long
as there is a steady and constant rate of flow for all of the
streams. In order to monitor the DUT performance for recovery times,
a set of route prefixes should be advertised before traffic is sent.
The traffic should be configured towards these routes.
Prefix-dependency behaviors are key in IP, and tests with route-
specific flows spread across the routing table will reveal this
dependency. Generating traffic to all of the prefixes reachable by
the protected tunnel (probably in a Round-Robin fashion, where the
traffic is destined to all the prefixes but one prefix at a time in a
cyclic manner) is not recommended. Round-Robin traffic generation is
not recommended to all prefixes, as time to hit all the prefixes may
be higher than the failover time. This phenomenon will reduce the
granularity of the measured results, and the results observed may not
be accurate.
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RFC 6894 MPLS Protection Mechanisms March 2013
5.8. Tester Capabilities
It is RECOMMENDED that the Tester used to execute each test case have
the following capabilities:
1. Ability to establish MPLS-TE tunnels and push/pop labels.
2. Ability to produce a failover event [RFC6414].
3. Ability to insert a timestamp in each data packet's IP payload.
4. An internal time clock to control timestamping, time
measurements, and time calculations.
5. Ability to disable or tune specific L2 and L3 protocol
functions on any interface.
6. Ability to react upon the receipt of path error from the PLR.
The Tester MAY be capable of making non-data-plane convergence
observations and use those observations for measurements.
5.9. Failover Time Measurement Methods
Failover time [RFC6414] is calculated using one of the following
three methods:
1. Packet-Loss-Based Method (PLBM): (Number of packets dropped/
packets per second * 1000) milliseconds. This method could
also be referred to as the Loss-Derived method.
2. Time-Based Loss Method (TBLM): This method relies on the
ability of the traffic generators to provide statistics that
reveal the duration of failure in milliseconds based on when
the packet loss occurred (interval between non-zero packet loss
and zero loss).
3. Timestamp-Based Method (TBM): This method of failover
calculation is based on the timestamp that gets transmitted as
payload in the packets originated by the generator. The
traffic analyzer records the timestamp of the last packet
received before the failover event and the first packet after
the failover and derives the time based on the difference
between these two timestamps. Note: The payload could also
contain sequence numbers for out-of-order packet calculation
and duplicate packets.
Papneja, et al. Informational [Page 10]RFC 6894 MPLS Protection Mechanisms March 2013
TBM would be able to detect reversion impairments beyond loss; thus,
it is RECOMMENDED as the failover time method.
6. Reference Test Setup
In addition to the general reference topology shown in Figure 1, this
section provides detailed insight into various proposed test setups
that should be considered for comprehensively benchmarking the
failover time in different roles along the primary tunnel.
This section proposes a set of topologies that covers all the
scenarios for local protection. All of these topologies can be
mapped to the reference topology shown in Figure 1. Topologies
provided in this section refer to the testbed required to benchmark
failover time when the DUT is configured as a PLR in either head-end
or midpoint role. Provided with each topology below is the label
stack at the PLR. Penultimate Hop Popping (PHP) MAY be used and must
be reported when used.
Figures 2 through 9 use the following convention and are subset of
Figure 1:
a) HE is Head-End
b) T/E is Tail-End
c) MID is Midpoint
d) MP is Merge Point
e) PLR is Point of Local Repair
f) PRI is Primary Path
g) BKP denotes Backup Path and Nodes
h) UR is Upstream Router
Papneja, et al. Informational [Page 11]RFC 6894 MPLS Protection Mechanisms March 2013
6.1. Link Protection
6.1.1. Link Protection: 1-Hop Primary (from PLR) and 1-Hop Backup
Tail-End Tunnels
+-------+ +--------+ +--------+
| R1 | | R2 | PRI| R3 |
| UR/HE |--| HE/MID |----| MP/T/E |
| | | PLR |----| |
+-------+ +--------+ BKP+--------+
Figure 2
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 0 0
Layer3 VPN (PE-PE) 1 1
Layer3 VPN (PE-P) 2 2
Layer2 VC (PE-PE) 1 1
Layer2 VC (PE-P) 2 2
Midpoint LSPs 0 0
Please note the following:
a) For the P-P case, R2 and R3 act as P routers
b) For the PE-PE cases, R2 acts as a PE and R3 acts as a remote PE
c) For the PE-P cases, R2 acts as a PE router, R3 acts as a P router,
and R5 acts as a remote PE router (please refer to Figure 1 for
complete setup)
d) For the midpoint case, R1, R2, and R3 act as HE, midpoint/PLR, and
tail-end, respectively (as shown in the figure above)
Papneja, et al. Informational [Page 12]RFC 6894 MPLS Protection Mechanisms March 2013
6.1.2. Link Protection: 1-Hop Primary (from PLR) and 2-Hop Backup
Tail-End Tunnels
+-------+ +--------+ +--------+
| R1 | | R2 | | R3 |
| UR/HE | | HE/MID |PRI | MP/T/E |
| |----| PLR |----| |
+-------+ +--------+ +--------+
|BKP |
| +--------+ |
| | R6 | |
|----| BKP |----|
| MID |
+--------+
Figure 3
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 0 1
Layer3 VPN (PE-PE) 1 2
Layer3 VPN (PE-P) 2 3
Layer2 VC (PE-PE) 1 2
Layer2 VC (PE-P) 2 3
Midpoint LSPs 0 1
Please note the following:
a) For the P-P case, R2 and R3 act as P routers
b) For PE-PE cases, R2 acts as a PE and R3 acts as a remote PE
c) For PE-P cases, R2 acts as a PE router, R3 acts as a P router, and
R5 acts as a remote PE router (please refer to Figure 1 for
complete setup)
d) For the midpoint case, R1, R2, and R3 act as HE, midpoint/PLR, and
tail-end, respectively (as shown in the figure above)
Papneja, et al. Informational [Page 13]RFC 6894 MPLS Protection Mechanisms March 2013
6.1.3. Link Protection: 2-Hop (or More) Primary (from PLR) and 1-Hop
Backup Tail-End Tunnels
+--------+ +--------+ +--------+ +--------+
| R1 | | R2 |PRI | R3 |PRI | R4 |
| UR/HE |----| HE/MID |----| MP/MID |------| T/E |
| | | PLR |----| | | |
+--------+ +--------+ BKP+--------+ +--------+
Figure 4
Traffic No. of Labels Num of labels
before failure after failure
IP TRAFFIC (P-P) 1 1
Layer3 VPN (PE-PE) 2 2
Layer3 VPN (PE-P) 3 3
Layer2 VC (PE-PE) 2 2
Layer2 VC (PE-P) 3 3
Midpoint LSPs 1 1
Please note the following:
a) For the P-P case, R2, R3, and R4 act as P routers
b) For PE-PE cases, R2 acts as a PE and R4 acts as a remote PE c) For
PE-P cases, R2 acts as a PE router, R3 acts as a P router, and R5
acts as remote PE router (please refer to Figure 1 for complete
setup)
d) For the midpoint case, R1, R2, R3, and R4 act as HE, midpoint/PLR,
and tail-end, respectively (as shown in the figure above)
Papneja, et al. Informational [Page 14]RFC 6894 MPLS Protection Mechanisms March 2013
6.1.4. Link Protection: 2-Hop (or More) Primary (from PLR) and 2-Hop
Backup Tail-End Tunnels
+--------+ +--------+PRI +--------+ PRI +--------+
| R1 | | R2 | | R3 | | R4 |
| UR/HE |----| HE/MID |----| MP/MID|------| T/E |
| | | PLR | | | | |
+--------+ +--------+ +--------+ +--------+
BKP| |
| +--------+ |
| | R6 | |
+---| BKP |-
| MID |
+--------+
Figure 5
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 1 2
Layer3 VPN (PE-PE) 2 3
Layer3 VPN (PE-P) 3 4
Layer2 VC (PE-PE) 2 3
Layer2 VC (PE-P) 3 4
Midpoint LSPs 1 2
Please note the following:
a) For the P-P case, R2, R3, and R4 act as P routers
b) For PE-PE cases, R2 acts as a PE and R4 acts as a remote PE
c) For PE-P cases, R2 acts as a PE router, R3 acts as a P router, and
R5 acts as remote PE router (please refer to Figure 1 for complete
setup)
d) For the midpoint case, R1, R2, R3 and R4 act as HE, midpoint/PLR,
and tail-end, respectively (as shown in the figure above)
Papneja, et al. Informational [Page 15]RFC 6894 MPLS Protection Mechanisms March 2013
6.2. Node Protection
6.2.1. Node Protection: 2-Hop Primary (from PLR) and 1-Hop Backup
Tail-End Tunnels
+--------+ +--------+ +--------+ +--------+
| R1 | | R2 |PRI | R3 | PRI | R4 |
| UR/HE |----| HE/MID |----| MID |------| MP/T/E |
| | | PLR | | | | |
+--------+ +--------+ +--------+ +--------+
|BKP |
-----------------------------
Figure 6
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 1 0
Layer3 VPN (PE-PE) 2 1
Layer3 VPN (PE-P) 3 2
Layer2 VC (PE-PE) 2 1
Layer2 VC (PE-P) 3 2
Midpoint LSPs 1 0
Please note the following:
a) For the P-P case, R2, R3, and R4 act as P routers
b) For PE-PE cases, R2 acts as a PE and R4 acts as a remote PE
c) For PE-P cases, R2 acts as a PE router, R4 acts as a P router, and
R5 acts as remote PE router (please refer to Figure 1 for complete
setup)
d) For the midpoint case, R1, R2, R3, and R4 act as HE, midpoint/PLR,
and tail-end, respectively (as shown in the figure above)
Papneja, et al. Informational [Page 16]RFC 6894 MPLS Protection Mechanisms March 2013
6.2.2. Node Protection: 2-Hop Primary (from PLR) and 2-Hop Backup
Tail-End Tunnels
+--------+ +--------+ +--------+ +--------+
| R1 | | R2 | | R3 | | R4 |
| UR/HE | | HE/MID |PRI | MID |PRI | MP/T/E |
| |----| PLR |----| |----| |
+--------+ +--------+ +--------+ +--------+
| |
BKP| +--------+ |
| | R6 | |
---------| BKP |---------
| MID |
+--------+
Figure 7
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 1 1
Layer3 VPN (PE-PE) 2 2
Layer3 VPN (PE-P) 3 3
Layer2 VC (PE-PE) 2 2
Layer2 VC (PE-P) 3 3
Midpoint LSPs 1 1
Please note the following:
a) For the P-P case, R2, R3, and R4 act as P routers
b) For PE-PE cases, R2 acts as a PE and R4 acts as a remote PE
c) For PE-P cases, R2 acts as a PE router, R4 acts as a P router, and
R5 acts as remote PE router (please refer to Figure 1 for complete
setup)
d) For the midpoint case, R1, R2, R3, and R4 act as HE, midpoint/PLR,
and tail-end, respectively (as shown in the figure above)
Papneja, et al. Informational [Page 17]RFC 6894 MPLS Protection Mechanisms March 2013
6.2.3. Node Protection: 3-Hop (or More) Primary (from PLR) and 1-Hop
Backup Tail-End Tunnels
+--------+ +--------+PRI+--------+PRI+--------+PRI+--------+
| R1 | | R2 | | R3 | | R4 | | R5 |
| UR/HE |--| HE/MID |---| MID |---| MP |---| T/E |
| | | PLR | | | | | | |
+--------+ +--------+ +--------+ +--------+ +--------+
BKP| |
--------------------------
Figure 8
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 1 1
Layer3 VPN (PE-PE) 2 2
Layer3 VPN (PE-P) 3 3
Layer2 VC (PE-PE) 2 2
Layer2 VC (PE-P) 3 3
Midpoint LSPs 1 1
Please note the following:
a) For the P-P case, R2, R3, R4, and R5 act as P routers
b) For PE-PE cases, R2 acts as a PE and R5 acts as a remote PE
c) For PE-P cases, R2 acts as a PE router, R4 acts as a P router, and
R5 acts as remote PE router (please refer to Figure 1 for complete
setup)
d) For the midpoint case, R1, R2, R3, R4, and R5 act as HE,
midpoint/PLR, and tail-end, respectively (as shown in the figure
above)
Papneja, et al. Informational [Page 18]RFC 6894 MPLS Protection Mechanisms March 2013
6.2.4. Node Protection: 3-Hop (or More) Primary (from PLR) and 2-Hop
Backup Tail-End Tunnels
+--------+ +--------+ +--------+ +--------+ +--------+
| R1 | | R2 | | R3 | | R4 | | R5 |
| UR/HE | | HE/MID |PRI| MID |PRI| MP |PRI| T/E |
| |-- | PLR |---| |---| |---| |
+--------+ +--------+ +--------+ +--------+ +--------+
BKP| |
| +--------+ |
| | R6 | |
---------| BKP |-------
| MID |
+--------+
Figure 9
Traffic No. of Labels No. of labels
before failure after failure
IP TRAFFIC (P-P) 1 2
Layer3 VPN (PE-PE) 2 3
Layer3 VPN (PE-P) 3 4
Layer2 VC (PE-PE) 2 3
Layer2 VC (PE-P) 3 4
Midpoint LSPs 1 2
Please note the following:
a) For the P-P case, R2, R3, R4, and R5 act as P routers
b) For PE-PE cases, R2 acts as a PE and R5 acts as a remote PE
c) For PE-P cases, R2 acts as a PE router, R4 acts as a P router,
and R5 acts as remote PE router (please refer to Figure 1 for
complete setup)
d) For the midpoint case, R1, R2, R3, R4, and R5 act as HE,
midpoint/PLR, and tail-end, respectively (as shown in the
figure above)
7. Test Methodology
The procedure described in this section can be applied to all eight
base test cases and the associated topologies. The backup as well as
the primary tunnels are configured to be alike in terms of bandwidth
usage. In order to benchmark failover with all possible label stack
depth applicable (as seen with current deployments), it is
RECOMMENDED to perform all of the test cases provided in this
section. The forwarding performance test cases in Section 7.1 MUST
be performed prior to performing the failover test cases.
Papneja, et al. Informational [Page 19]RFC 6894 MPLS Protection Mechanisms March 2013
The considerations of Section 4 of [RFC2544] are applicable when
evaluating the results obtained using these methodologies as well.
7.1. MPLS-FRR Forwarding Performance
Benchmarking failover time [RFC6414] for MPLS protection first
requires a baseline measurement of the forwarding performance of the
test topology, including the DUT. Forwarding performance is
benchmarked by the throughput as defined in [RFC5695] and measured in
units of packets per second (pps). This section provides two test
cases to benchmark forwarding performance. These are with the DUT
configured as a head-end PLR, midpoint PLR, and egress PLR.
7.1.1. Head-End PLR Forwarding Performance
Objective:
To benchmark the maximum rate (pps) on the PLR (as head-end) over
the primary LSP and backup LSP.
Test Setup:
A. Select any one topology out of the eight from Section 6.
B. Select or enable IP, L3 VPN, or L2 VPN services with the DUT
as head-end PLR.
C. The DUT will also have two interfaces connected to the traffic
generator/analyzer. (If the node downstream of the PLR is not
a simulated node, then the ingress of the tunnel should have
one link connected to the traffic generator, and the node
downstream of the PLR or the egress of the tunnel should have
a link connected to the traffic analyzer).
Procedure:
1. Establish the primary LSP on R2 required by the topology
selected.
2. Establish the backup LSP on R2 required by the selected
topology.
3. Verify that primary and backup LSPs are up and that the
primary is protected.
4. Verify that Fast Reroute protection is enabled and ready.
5. Set up traffic streams as described in Section 5.7.
Papneja, et al. Informational [Page 20]RFC 6894 MPLS Protection Mechanisms March 2013
6. Send MPLS traffic over the primary LSP at the throughput
supported by the DUT (Section 6 of [RFC2544]).
7. Record the throughput over the primary LSP.
8. Trigger a link failure as described in Section 5.1.
9. Verify that the offered load gets mapped to the backup tunnel
and measure the Additive Backup Delay [RFC6414].
10. 30 seconds after failover, stop the offered load and measure
the throughput, packet loss, out-of-order packets, and
duplicate packets over the backup LSP.
11. Adjust the offered load and repeat steps 6 through 10 until
the throughput values for the primary and backup LSPs are
equal.
12. Record the final throughput, which corresponds to the offered
load that will be used for the head-end PLR failover test
cases.
7.1.2. Midpoint PLR Forwarding Performance
Objective:
To benchmark the maximum rate (pps) on the PLR (as midpoint) over
the primary LSP and backup LSP.
Test Setup:
A. Select any one topology out of the eight from Section 6.
B. The DUT will also have two interfaces connected to the traffic
generator.
Procedure:
1. Establish the primary LSP on R1 required by the topology
selected.
2. Establish the backup LSP on R2 required by the selected
topology.
3. Verify that primary and backup LSPs are up and that the
primary is protected.
4. Verify that Fast Reroute protection is enabled and ready.
Papneja, et al. Informational [Page 21]RFC 6894 MPLS Protection Mechanisms March 2013
5. Set up traffic streams as described in Section 5.7.
6. Send MPLS traffic over the primary LSP at the throughput
supported by the DUT (Section 6 of [RFC2544]).
7. Record the throughput over the primary LSP.
8. Trigger a link failure as described in Section 5.1.
9. Verify that the offered load gets mapped to the backup tunnel
and measure the Additive Backup Delay [RFC6414].
10. 30 seconds after failover, stop the offered load and measure
the throughput, packet loss, out-of-order packets, and
duplicate packets over the backup LSP.
11. Adjust the offered load and repeat steps 6 through 10 until
the throughput values for the primary and backup LSPs are
equal.
12. Record the final throughput, which corresponds to the offered
load that will be used for the midpoint PLR failover test
cases.
7.2. Head-End PLR with Link Failure
Objective:
To benchmark the MPLS failover time due to link failure events
described in Section 5.1 experienced by the DUT, which is the
head-end PLR.
Test Setup:
A. Select any one topology out of the eight from Section 6.
B. Select or enable IP, L3 VPN, or L2 VPN services with the DUT
as head-end PLR.
C. The DUT will also have two interfaces connected to the traffic
generator/analyzer. (If the node downstream of the PLR is not
a simulated node, then the ingress of the tunnel should have
one link connected to the traffic generator, and the node
downstream to the PLR or the egress of the tunnel should have
a link connected to the traffic analyzer).
Papneja, et al. Informational [Page 22]RFC 6894 MPLS Protection Mechanisms March 2013
Test Configuration:
1. Configure the number of primaries on R2 and the backups on R2
as required by the topology selected.
2. Configure the test setup to support reversion.
3. Advertise prefixes (as per the FRR Scalability Table in
Appendix A) by the tail-end.
Procedure:
The test case in Section 7.1.1, "Head-End PLR Forwarding
Performance", MUST be completed first to obtain the throughput to
use as the offered load.
1. Establish the primary LSP on R2 required by the topology
selected.
2. Establish the backup LSP on R2 required by the selected
topology.
3. Verify that primary and backup LSPs are up and that the
primary is protected.
4. Verify that Fast Reroute protection is enabled and ready.
5. Set up traffic streams for the offered load as described in
Section 5.7.
6. Provide the offered load from the tester at the throughput
[RFC1242] level obtained from the test case in Section 7.1.1.
7. Verify that traffic is switched over the primary LSP without
packet loss.
8. Trigger a link failure as described in Section 5.1.
9. Verify that the offered load gets mapped to the backup tunnel
and measure the Additive Backup Delay [RFC6414].
10. 30 seconds after failover, stop the offered load and measure
the total failover packet loss [RFC6414].
11. Calculate the failover time benchmark using the selected
failover time calculation method (TBLM, PLBM, or TBM)
[RFC6414].
Papneja, et al. Informational [Page 23]RFC 6894 MPLS Protection Mechanisms March 2013
12. Restart the offered load and restore the primary LSP to
verify that reversion occurs and measure the Reversion Packet
Loss [RFC6414].
13. Calculate the Reversion Time benchmark using the selected
failover time calculation method (TBLM, PLBM, or TBM)
[RFC6414].
14. Verify that the head-end signals new LSP and protection
should be in place again.
It is RECOMMENDED that this procedure be repeated for each of the
link failure triggers defined in Section 5.1.
7.3. Midpoint PLR with Link Failure
Objective:
To benchmark the MPLS failover time due to link failure events
described in Section 5.1 experienced by the DUT, which is the
midpoint PLR.
Test Setup:
A. Select any one topology out of the eight from Section 6.
B. The DUT will also have two interfaces connected to the traffic
generator.
Test Configuration:
1. Configure the number of primaries on R1 and the backups on R2
as required by the topology selected.
2. Configure the test setup to support reversion.
3. Advertise prefixes (as per the FRR Scalability Table in
Appendix A) by the tail-end.
Procedure:
The test case in Section 7.1.2, "Midpoint PLR Forwarding
Performance", MUST be completed first to obtain the throughput to
use as the offered load.
1. Establish the primary LSP on R1 as required by the topology
selected.
Papneja, et al. Informational [Page 24]RFC 6894 MPLS Protection Mechanisms March 2013
2. Establish the backup LSP on R2 as required by the selected
topology.
3. Perform steps 3 through 14 from Section 7.2, "Head-End PLR
with Link Failure".
It is RECOMMENDED that this procedure be repeated for each of the
link failure triggers defined in section 5.1.
7.4. Head-End PLR with Node Failure
Objective:
To benchmark the MPLS failover time due to node failure events
described in Section 5.1 experienced by the DUT, which is the
head-end PLR.
Test Setup:
A. Select any one topology out of the eight from Section 6.
B. Select or enable IP, L3 VPN, or L2 VPN services with the DUT
as head-end PLR.
C. The DUT will also have two interfaces connected to the traffic
generator/analyzer.
Test Configuration:
1. Configure the number of primaries on R2 and the backups on R2
as required by the topology selected.
2. Configure the test setup to support reversion.
3. Advertise prefixes (as per the FRR Scalability Table in
Appendix A) by the tail-end.
Procedure:
The test case in Section 7.1.1, "Head-End PLR Forwarding
Performance", MUST be completed first to obtain the throughput to
use as the offered load.
1. Establish the primary LSP on R2 as required by the topology
selected.
2. Establish the backup LSP on R2 as required by the selected
topology.
Papneja, et al. Informational [Page 25]RFC 6894 MPLS Protection Mechanisms March 2013
3. Verify that the primary and backup LSPs are up and that the
primary is protected.
4. Verify that Fast Reroute protection is enabled and ready.
5. Set up traffic streams for the offered load as described in
Section 5.7.
6. Provide the offered load from the tester at the throughput
[RFC1242] level obtained from the test case in Section 7.1.1.
7. Verify that traffic is switched over the primary LSP without
packet loss.
8. Trigger a node failure as described in Section 5.1.
9. Perform steps 9 through 14 in Section 7.2, "Head-End PLR with
Link Failure".
It is RECOMMENDED that this procedure be repeated for each of the
node failure triggers defined in Section 5.1.
7.5. Midpoint PLR with Node Failure
Objective:
To benchmark the MPLS failover time due to node failure events
described in Section 5.1 experienced by the DUT, which is the
midpoint PLR.
Test Setup:
A. Select any one topology from Sections 6.1 to 6.2.
B. The DUT will also have two interfaces connected to the traffic
generator.
Test Configuration:
1. Configure the number of primaries on R1 and the backups on R2
as required by the topology selected.
2. Configure the test setup to support reversion.
3. Advertise prefixes (as per the FRR Scalability Table in
Appendix A) by the tail-end.
Papneja, et al. Informational [Page 26]RFC 6894 MPLS Protection Mechanisms March 2013
Procedure:
The test case in Section 7.1.1, "Midpoint PLR Forwarding
Performance", MUST be completed first to obtain the throughput to
use as the offered load.
1. Establish the primary LSP on R1 as required by the topology
selected.
2. Establish the backup LSP on R2 as required by the selected
topology.
3. Verify that the primary and backup LSPs are up and that the
primary is protected.
4. Verify that Fast Reroute protection is enabled and ready.
5. Set up traffic streams for the offered load as described in
Section 5.7.
6. Provide the offered load from the tester at the throughput
[RFC1242] level obtained from the test case in Section 7.1.1.
7. Verify that traffic is switched over the primary LSP without
packet loss.
8. Trigger a node failure as described in Section 5.1.
9. Perform steps 9 through 14 in Section 7.2, "Head-End PLR with
Link Failure".
It is RECOMMENDED that this procedure be repeated for each of the
node failure triggers defined in Section 5.1.
8. Reporting Format
For each test, it is RECOMMENDED that the results be reported in the
following format.
Parameter Units
IGP used for the test ISIS-TE / OSPF-TE
Interface types Gige,POS,ATM,VLAN, etc.
Packet Sizes offered to the DUT Bytes (at L3)
Offered Load (Throughput) Packets per second
Papneja, et al. Informational [Page 27]RFC 6894 MPLS Protection Mechanisms March 2013
IGP routes advertised Number of IGP routes
Penultimate Hop Popping Used/Not Used
RSVP hello timers Milliseconds
Number of Protected tunnels Number of tunnels
Number of VPN routes installed Number of VPN routes
on the head-end
Number of VC tunnels Number of VC tunnels
Number of midpoint tunnels Number of tunnels
Number of Prefixes protected by Number of LSPs
Primary
Topology being used Section number, and
figure reference
Failover event Event type
Reoptimization Yes/No
Benchmarks (to be recorded for each test case):
Failover-
Failover Time seconds
Failover Packet Loss packets
Additive Backup Delay seconds
Out-of-Order Packets packets
Duplicate Packets packets
Failover Time Calculation Method Method Used
Reversion-
Reversion Time seconds
Reversion Packet Loss packets
Additive Backup Delay seconds
Out-of-Order Packets packets
Duplicate Packets packets
Failover Time Calculation Method Method Used
Papneja, et al. Informational [Page 28]RFC 6894 MPLS Protection Mechanisms March 2013
9. Security Considerations
Benchmarking activities as described in this memo are limited to
technology characterization using controlled stimuli in a laboratory
environment, with dedicated address space and the constraints
specified in the sections above.
The benchmarking network topology will be an independent test setup
and MUST NOT be connected to devices that may forward the test
traffic into a production network, or misroute traffic to the test
management network.
Further, benchmarking is performed on a "black-box" basis, relying
solely on measurements observable external to the DUT/SUT.
Special capabilities SHOULD NOT exist in the DUT/SUT specifically for
benchmarking purposes. Any implications for network security arising
from the DUT/SUT SHOULD be identical in the lab and in production
networks.
10. Acknowledgements
We would like to thank Jean Philip Vasseur for his invaluable input
to the document, Curtis Villamizar for his contribution in suggesting
text on the definition and need for benchmarking Correlated failures,
and Bhavani Parise for his textual input and review. Additionally,
we would like to thank Al Morton, Arun Gandhi, Amrit Hanspal, Karu
Ratnam, Raveesh Janardan, Andrey Kiselev, and Mohan Nanduri for their
formal reviews of this document.
11. References
11.1. Normative References
[RFC1242] Bradner, S., "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, July 1991.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2544] Bradner, S. and J. McQuaid, "Benchmarking Methodology for
Network Interconnect Devices", RFC 2544, March 1999.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
Papneja, et al. Informational [Page 29]RFC 6894 MPLS Protection Mechanisms March 2013
[RFC5695] Akhter, A., Asati, R., and C. Pignataro, "MPLS Forwarding
Benchmarking Methodology for IP Flows", RFC 5695, November
2009.
[RFC6412] Poretsky, S., Imhoff, B., and K. Michielsen, "Terminology
for Benchmarking Link-State IGP Data-Plane Route
Convergence", RFC 6412, November 2011.
[RFC6414] Poretsky, S., Papneja, R., Karthik, J., and S. Vapiwala,
"Benchmarking Terminology for Protection Performance", RFC
6414, November 2011.
11.2. Informative References
[RFC2285] Mandeville, R., "Benchmarking Terminology for LAN
Switching Devices", RFC 2285, February 1998.
[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
Extensions in Support of Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 4202, October 2005.
[RFC4689] Poretsky, S., Perser, J., Erramilli, S., and S. Khurana,
"Terminology for Benchmarking Network-layer Traffic
Control Mechanisms", RFC 4689, October 2006.
Papneja, et al. Informational [Page 30]RFC 6894 MPLS Protection Mechanisms March 2013
Appendix A. Fast Reroute Scalability Table
This section provides the recommended numbers for evaluating the
scalability of fast reroute implementations. It also recommends the
typical numbers for IGP/VPNv4 Prefixes, LSP Tunnels, and VC entries.
Based on the features supported by the DUT, appropriate scaling
limits can be used for the testbed.
A.1. FRR IGP Table
No. of Head-End TE Tunnels IGP Prefixes
1 100
1 500
1 1000
1 2000
1 5000
2 (Load Balance) 100
2 (Load Balance) 500
2 (Load Balance) 1000
2 (Load Balance) 2000
2 (Load Balance) 5000
100 100
500 500
1000 1000
2000 2000
Papneja, et al. Informational [Page 31]RFC 6894 MPLS Protection Mechanisms March 2013
A.2. FRR VPN Table
No. of Head-End TE Tunnels VPNv4 Prefixes
1 100
1 500
1 1000
1 2000
1 5000
1 10000
1 20000
1 Max
2 (Load Balance) 100
2 (Load Balance) 500
2 (Load Balance) 1000
2 (Load Balance) 2000
2 (Load Balance) 5000
2 (Load Balance) 10000
2 (Load Balance) 20000
2 (Load Balance) Max
Papneja, et al. Informational [Page 32]RFC 6894 MPLS Protection Mechanisms March 2013
A.3. FRR Midpoint LSP Table
The number of midpoint TE LSPs could be configured at recommended
levels -- 100, 500, 1000, 2000, or max supported number.
A.4. FRR VC Table
No. of Head-End TE Tunnels VC entries
1 100
1 500
1 1000
1 2000
1 Max
100 100
500 500
1000 1000
2000 2000
Papneja, et al. Informational [Page 33]RFC 6894 MPLS Protection Mechanisms March 2013
Appendix B. Abbreviations
AIS - Alarm Indication Signal
BFD - Bidirectional Fault Detection
BGP - Border Gateway Protocol
BKP - Backup Path and Nodes
CE - Customer Edge
DUT - Device Under Test
FRR - Fast Reroute
HE - Head-End
IGP - Interior Gateway Protocol
IP - Internet Protocol
LOS - Loss of Signal
LSP - Label Switched Path
MID - Midpoint
MP - Merge Point
MPLS - Multiprotocol Label Switching
N-Nhop - Next - Next Hop
Nhop - Next Hop
OIR - Online Insertion and Removal
P - Provider
PE - Provider Edge
PHP - Penultimate Hop Popping
PLBM - Packet-Loss-Based Method
PLR - Point of Local Repair
PRI - Primary Path
RSVP - Resource reSerVation Protocol
RX - Receive
SRLG - Shared Risk Link Group
TA - Traffic Analyzer
TBM - Timestamp-Based Method
TE - Traffic Engineering
TG - Traffic Generator
TX - Transmit
UR - Upstream Router
VC - Virtual Circuit
VPN - Virtual Private Network
Papneja, et al. Informational [Page 34]
RFC 6894 MPLS Protection Mechanisms March 2013
Authors' Addresses
Rajiv Papneja
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95050
USA
EMail: rajiv.papneja@huawei.com
Samir Vapiwala
Cisco Systems
300 Beaver Brook Road
Boxborough, MA 01719
USA
EMail: svapiwal@cisco.com
Jay Karthik
Cisco Systems
300 Beaver Brook Road
Boxborough, MA 01719
USA
EMail: jkarthik@cisco.com
Scott Poretsky
Allot Communications
300 TradeCenter
Woburn, MA 01801
USA
EMail: sporetsky@allot.com
Shankar Rao
Qwest Communications
950 17th Street
Suite 1900
Denver, CO 80210
USA
EMail: shankar.rao@du.edu
JL. Le Roux
France Telecom
2 av Pierre Marzin
22300 Lannion
France
EMail: jeanlouis.leroux@orange.com
Papneja, et al. Informational [Page 35]
