Network Working Group
INTERNET-DRAFT
Expires in: April 2005
Scott Poretsky
Quarry Technologies
Brent Imhoff
LightCore
October 2004
Benchmarking Methodology for
IGP Data Plane Route Convergence
<draft-ietf-bmwg-igp-dataplane-conv-meth-04.txt>
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ABSTRACT
This draft describes the methodology for benchmarking IGP Route
Convergence as described in Applicability document [1] and
Terminology document [2]. The methodology and terminology are
to be used for benchmarking route convergence and can be applied
to any link-state IGP such as ISIS [3] and OSPF [4]. The terms
used in the procedures provided within this document are
defined in [2].
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Table of Contents
1. Introduction ...............................................2
2. Existing definitions .......................................2
3. Test Setup..................................................3
3.1 Test Topologies............................................3
3.2 Test Considerations........................................4
3.2.1 IGP Selection............................................4
3.2.2 BGP Configuration........................................4
3.2.3 IGP Route Scaling........................................5
3.2.4 Timers...................................................5
3.2.5 Convergence Time Metrics.................................5
3.2.6 Offered Load.............................................5
3.2.7 Interface Types..........................................5
3.3 Reporting Format...........................................6
4. Test Cases..................................................6
4.1 Convergence Due to Link Failure............................6
4.1.1 Convergence Due to Local Interface Failure...............6
4.1.2 Convergence Due to Neighbor Interface Failure............7
4.1.3 Convergence Due to Remote Interface Failure..............7
4.2 Convergence Due to Layer 2 Session Failure.................8
4.3 Convergence Due to IGP Adjacency Failure...................9
4.4 Convergence Due to Route Withdrawal........................9
4.5 Convergence Due to Cost Change.............................10
4.6 Convergence Due to ECMP Member Interface Failure...........10
4.7 Convergence Due to Parallel Link Interface Failure.........11
5. Security Considerations.....................................12
6. References..................................................12
7. Author's Address............................................12
1. Introduction
This draft describes the methodology for benchmarking IGP Route
Convergence. The applicability of this testing is described in
[1] and the new terminology that it introduces is defined in [2].
Service Providers use IGP Convergence time as a key metric of
router design and architecture. Customers of Service Providers
observe convergence time by packet loss, so IGP Route Convergence
is considered a Direct Measure of Quality (DMOQ). The test cases
in this document are black-box tests that emulate the network
events that cause route convergence, as described in [1]. The
black-box test designs benchmark the data plane accounting for
all of the factors contributing to convergence time, as discussed
in [1]. The methodology (and terminology) for benchmarking route
convergence can be applied to any link-state IGP such as ISIS [3]
and OSPF [4].
2. Existing definitions
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.
Terms related to IGP Convergence are defined in [2].
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3. Test Setup
3.1 Test Topologies
Figure 1 shows the test topology to measure IGP Route Convergence due
to local Convergence Events such as SONET Link Failure, Layer 2 Session
Failure, IGP Adjacency Failure, Route Withdrawal, and route cost
change. These test cases discussed in section 4 provide route
convergence times that account for the Event Detection time, SPF
Processing time, and FIB Update time. These times are measured
by observing packet loss in the data plane.
--------- Ingress Interface ---------
| |<------------------------------| |
| | | |
| | Preferred Egress Interface | |
| DUT |------------------------------>|Tester |
| | | |
| |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~>| |
| | Next-Best Egress Interface | |
--------- ---------
Figure 1. IGP Route Convergence Test Topology for Local Changes
Figure 2 shows the test topology to measure IGP Route Convergence
time due to remote changes in the network topology. These times are
measured by observing packet loss in the data plane. In this
topology the three routers are considered a System Under Test (SUT).
NOTE: All routers in the SUT must be the same model and identically configured.
----- -----------
| | Preferred | |
----- |R2 |---------------------->| |
| |-->| | Egress Interface | |
| | ----- | |
|R1 | | Tester |
| | ----- | |
| |-->| | Next-Best | |
----- |R3 |~~~~~~~~~~~~~~~~~~~~~~>| |
^ | | Egress Interface | |
| ----- -----------
| |
|--------------------------------------
Ingress Interface
Figure 2. IGP Route Convergence Test Topology
for Remote Changes
Figure 3 shows the test topology to measure IGP Route Convergence
time with members of an Equal Cost Multipath (ECMP) Set. These times are
measured by observing packet loss in the data plane. In this topology,
the DUT
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IGP Data Plane Route Convergence
is configured with each Egress interface as a member of an ECMP set
and the Tester emulates multiple next-hop routers (emulates one
router for each member).
--------- Ingress Interface ---------
| |<--------------------------------| |
| | | |
| | ECMP Set Interface 1 | |
| DUT |-------------------------------->| Tester|
| | . | |
| | . | |
| | . | |
| |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~>| |
| | ECMP Set Interface N | |
--------- ---------
Figure 3. IGP Route Convergence Test Topology
for ECMP Convergence
Figure 4 shows the test topology to measure IGP Route Convergence
time with members of a Parallel Link. These times are measured by
observing packet loss in the data plane. In this topology, the DUT
is configured with each Egress interface as a member of a Parallel
Link and the Tester emulates the single next-hop router.
--------- Ingress Interface ---------
| |<--------------------------------| |
| | | |
| | Parallel Link Interface 1 | |
| DUT |-------------------------------->| Tester|
| | . | |
| | . | |
| | . | |
| |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~>| |
| | Parallel Link Interface N | |
--------- ---------
Figure 4. IGP Route Convergence Test Topology
for Parallel Link Convergence
3.2 Test Considerations
3.2.1 IGP Selection
The test cases described in section 4 can be used for ISIS or
OSPF. The Route Convergence test methodology for both is
identical. The IGP adjacencies are established on the Preferred
Egress Interface and Next-Best Egress Interface.
3.2.2 BGP Configuration
The obtained results for IGP Route Convergence may vary if
BGP routes are installed. It is recommended that the IGP
Convergence times be benchmarked without BGP routes installed.
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3.2.3 IGP Route Scaling
The number of IGP routes will impact the measured IGP Route
Convergence because convergence for the entire IGP route table is
measured. For results similar to those that would be observed in
an operational network it is recommended that the number of
installed routes closely approximate that for routers in the
network. The number of areas (for OSPF) and levels (for ISIS) can
impact the benchmark results.
3.2.4 Timers
There are some timers that will impact the measured IGP Convergence
time. The following timers should be configured to the minimum value
prior to beginning execution of the test cases:
Timer Recommended Value
----- -----------------
SONET Failure Indication Delay <10milliseconds
IGP Hello Timer 1 second
IGP Dead-Interval 3 seconds
LSA Generation Delay 0
LSA Flood Packet Pacing 0
LSA Retransmission Packet Pacing 0
SPF Delay 0
3.2.5 Convergence Time Metrics
The recommended value for the Packet Sampling Interval [2] is
100 milliseconds. Rate-Derived Convergence Time [2] is the
preferred benchmark for IGP Route Convergence. This benchmark
must always be reported when the
Packet Sampling Interval [2] <= 100 milliseconds.
If the test equipment does not permit the Packet Sampling
Interval to be set as low as 100 msec, then both the
Rate-Derived Convergence Time and Loss-Derived Convergence
Time [2] must be reported.
3.2.6 Offered Load
An offered Load of maximum forwarding rate at a fixed packet size
is recommended for accurate measurement. The duration of offered
load must be greater than the convergence time. The destinations
for the offered load must be distributed such that all routes are
matched. This enables Full Convergence [2] to be observed.
3.2.7 Interface Types
All test cases in this methodology document may be executed with
any interface type. SONET is recommended and specifically
mentioned in the procedures because it can be configured to have
no or negligible affect on the measured convergence time.
Ethernet (10Mb, 100Mb, 1Gb, and 10Gb) is not preferred since
broadcast media are unable to detect loss of host and rely upon
IGP Hellos to detect session loss.
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3.3 Reporting Format
For each test case, it is recommended that the following reporting
format be completed:
Parameter Units
--------- -----
IGP (ISIS or OSPF)
Interface Type (GigE, POS, ATM, etc.)
Packet Size bytes
IGP Routes number of IGP routes
Packet Sampling Interval seconds or milliseconds
IGP Timer Values
SONET Failure Indication Delay seconds or milliseconds
IGP Hello Timer seconds or milliseconds
IGP Dead-Interval seconds or milliseconds
LSA Generation Delay seconds or milliseconds
LSA Flood Packet Pacing seconds or milliseconds
LSA Retransmission Packet Pacing seconds or milliseconds
SPF Delay seconds or milliseconds
Benchmarks
Rate-Derived Convergence Time seconds or milliseconds
Loss-Derived Convergence Time seconds or milliseconds
Restoration Convergence Time seconds or milliseconds
4. Test Cases
4.1 Convergence Due to Link Failure
4.1.1 Convergence Due to Local Interface Failure
Objective
To obtain the IGP Route Convergence due to a local link
failure event at the DUT's Local Interface.
Procedure
1. Advertise matching IGP routes from Tester to DUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 1. Set the cost of the
routes so that the Preferred Egress Interface is the preferred
next-hop.
2. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress Interface
[2].
3. Verify traffic routed over Preferred Egress Interface.
4. Remove SONET on DUT's Local Interface [2] by performing an
administrative shutdown of the interface.
5. Measure Rate-Derived Convergence Time [2] as DUT detects the
link down event and converges all IGP routes and traffic over
the Next-Best Egress Interface.
6. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
7. Restore SONET on DUT's Local Interface by administratively
enabling the interface.
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8. Measure Restoration Convergence Time [2] as DUT detects the link
up event and converges all IGP routes and traffic back to the
Preferred Egress Interface.
Results
The measured IGP Convergence time is influenced by the Local
SONET indication, SPF delay, SPF Holdtime, SPF Execution
Time, Tree Build Time, and Hardware Update Time.
4.1.2 Convergence Due to Neighbor Interface Failure
Objective
To obtain the IGP Route Convergence due to a local link
failure event at the Tester's Neighbor Interface.
Procedure
1. Advertise matching IGP routes from Tester to DUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 1. Set the cost of
the routes so that the Preferred Egress Interface is the
preferred next-hop.
2. Send traffic at maximum forwarding rate to destinations matching
all IGP routes from Tester to DUT on Ingress Interface [2].
3. Verify traffic routed over Preferred Egress Interface.
4. Remove SONET on Tester's Neighbor Interface [2] connected to
DUT' s Preferred Egress Interface.
5. Measure Rate-Derived Convergence Time [2] as DUT detects the
link down event and converges all IGP routes and traffic over
the Next-Best Egress Interface.
6. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
7. Restore SONET on Tester's Neighbor Interface connected to
DUT's Preferred Egress Interface.
8. Measure Restoration Convergence Time [2] as DUT detects the
link up event and converges all IGP routes and traffic back to
the Preferred Egress Interface.
Results
The measured IGP Convergence time is influenced by the Local
SONET indication, SPF delay, SPF Holdtime, SPF Execution
Time, Tree Build Time, and Hardware Update Time.
4.1.3 Convergence Due to Remote Interface Failure
Objective
To obtain the IGP Route Convergence due to a Remote Interface
Failure event.
Procedure
1. Advertise matching IGP routes from Tester to SUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 2. Set the cost of the
routes so that the Preferred Egress Interface is the preferred
next-hop.
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2. Send traffic at maximum forwarding rate to destinations matching
all IGP routes from Tester to DUT on Ingress Interface [2].
3. Verify traffic is routed over Preferred Egress Interface.
4. Remove SONET on Tester's Neighbor Interface [2] connected to
SUT' s Preferred Egress Interface.
5. Measure Rate-Derived Convergence Time [2] as SUT detects
the link down event and converges all IGP routes and traffic
over the Next-Best Egress Interface.
6. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
7. Restore SONET on Tester's Neighbor Interface connected to
DUT's Preferred Egress Interface.
8. Measure Restoration Convergence Time [2] as DUT detects the
link up event and converges all IGP routes and traffic back to
the Preferred Egress Interface.
Results
The measured IGP Convergence time is influenced by the
SONET failure indication, LSA/LSP Flood Packet Pacing,
LSA/LSP Retransmission Packet Pacing, LSA/LSP Generation
time, SPF delay, SPF Holdtime, SPF Execution Time, Tree
Build Time, and Hardware Update Time. The additional
convergence time contributed by LSP Propagation can be
obtained by subtracting the Rate-Derived Convergence Time
measured in 4.1.2 (Convergence Due to Neighbor Interface
Failure) from the Rate-Derived Convergence Time measured in
this test case.
4.2 Convergence Due to Layer 2 Session Failure
Objective
To obtain the IGP Route Convergence due to a Local Layer 2 Session
failure event.
Procedure
1. Advertise matching IGP routes from Tester to DUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 1. Set the cost of
the routes so that the IGP routes along the Preferred Egress
Interface is the preferred next-hop.
2. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress
Interface [2].
3. Verify traffic routed over Preferred Egress Interface.
4. Remove Layer 2 session from Tester's Neighbor Interface [2]
connected to Preferred Egress Interface.
5. Measure Rate-Derived Convergence Time [2] as DUT detects the
Layer 2 session down event and converges all IGP routes and
traffic over the Next-Best Egress Interface.
6. Restore Layer 2 session on DUT's Preferred Egress Interface.
7. Measure Restoration Convergence Time [2] as DUT detects the
session up event and converges all IGP routes and traffic over
the Preferred Egress Interface.
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Results
The measured IGP Convergence time is influenced by the Layer 2
failure indication, SPF delay, SPF Holdtime, SPF Execution
Time, Tree Build Time, and Hardware Update Time.
4.3 Convergence Due to IGP Adjacency Failure
Objective
To obtain the IGP Route Convergence due to a Local IGP Adjacency
failure event.
Procedure
1. Advertise matching IGP routes from Tester to DUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 1. Set the cost of
the routes so that the Preferred Egress Interface is the
preferred next-hop.
2. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress
Interface [2].
3. Verify traffic routed over Preferred Egress Interface.
4. Remove IGP adjacency from Tester's Neighbor Interface [2]
connected to Preferred Egress Interface.
5. Measure Rate-Derived Convergence Time [2] as DUT detects the
IGP session failure event and converges all IGP routes and
traffic over the Next-Best Egress Interface.
6. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
7. Restore IGP session on DUT's Preferred Egress Interface.
8. Measure Restoration Convergence Time [2] as DUT detects the
session up event and converges all IGP routes and traffic over
the Preferred Egress Interface.
Results
The measured IGP Convergence time is influenced by the IGP
Hello Interval, IGP Dead Interval, SPF delay, SPF Holdtime,
SPF Execution Time, Tree Build Time, and Hardware Update
Time.
4.4 Convergence Due to Route Withdrawal
Objective
To obtain the IGP Route Convergence due to Route Withdrawal.
Procedure
1. Advertise matching IGP routes from Tester to DUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 1. Set the cost of
the routes so that the Preferred Egress Interface is the
preferred next-hop.
2. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress
Interface [2].
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3. Verify traffic routed over Preferred Egress Interface.
4. Tester withdraws all IGP routes from DUT's Local Interface
on Preferred Egress Interface.
6. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
7. Re-advertise IGP routes to DUT's Preferred Egress Interface.
8. Measure Restoration Convergence Time [2] as DUT converges all
IGP routes and traffic over the Preferred Egress Interface.
Results
The measured IGP Convergence time is the SPF Processing and FIB
Update time as influenced by the SPF delay, SPF Holdtime,
SPF Execution Time, Tree Build Time, and Hardware Update Time.
4.5 Convergence Due to Cost Change
Objective
To obtain the IGP Route Convergence due to route cost change.
Procedure
1. Advertise matching IGP routes from Tester to DUT on
Preferred Egress Interface [2] and Next-Best Egress Interface
[2] using the topology shown in Figure 1. Set the cost of
the routes so that the Preferred Egress Interface is the
preferred next-hop.
2. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress
Interface [2].
3. Verify traffic routed over Preferred Egress Interface.
4. Tester increases cost for all IGP routes at DUT's Preferred
Egress Interface so that the Next-Best Egress Interface
has lower cost and becomes preferred path.
5. Measure Rate-Derived Convergence Time [2] as DUT detects the
cost change event and converges all IGP routes and traffic
over the Next-Best Egress Interface.
6. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
7. Re-advertise IGP routes to DUT's Preferred Egress Interface
with original lower cost metric.
8. Measure Restoration Convergence Time [2] as DUT converges all
IGP routes and traffic over the Preferred Egress Interface.
Results
There should be no measured packet loss for this case.
4.6 Convergence Due to ECMP Member Interface Failure
Objective
To obtain the IGP Route Convergence due to a local link
failure event of an ECMP Member.
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Procedure
1. Configure ECMP Set as shown in Figure 3.
2. Advertise matching IGP routes from Tester to DUT on
each ECMP member.
3. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress
Interface [2].
4. Verify traffic routed over all members of ECMP Set.
5. Remove SONET on Tester's Neighbor Interface [2] connected to
one of the DUT's ECMP member interfaces.
6. Measure Rate-Derived Convergence Time [2] as DUT detects the
link down event and converges all IGP routes and traffic
over the other ECMP members.
7. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
8. Restore SONET on Tester's Neighbor Interface connected to
DUT's ECMP member interface.
9. Measure Restoration Convergence Time [2] as DUT detects the
link up event and converges IGP routes and some distribution
of traffic over the restored ECMP member.
Results
The measured IGP Convergence time is influenced by the Local
SONET indication, Tree Build Time, and Hardware Update Time.
4.7 Convergence Due to Parallel Link Interface Failure
Objective
To obtain the IGP Route Convergence due to a local link failure
event for a Member of a Parallel Link. The links can be used for
data Load Balancing
Procedure
1. Configure Parallel Link as shown in Figure 4.
2. Advertise matching IGP routes from Tester to DUT on
each Parallel Link member.
3. Send traffic at maximum forwarding rate to destinations
matching all IGP routes from Tester to DUT on Ingress
Interface [2].
4. Verify traffic routed over all members of Parallel Link.
5. Remove SONET on Tester's Neighbor Interface [2] connected to
one of the DUT's Parallel Link member interfaces.
6. Measure Rate-Derived Convergence Time [2] as DUT detects the
link down event and converges all IGP routes and traffic over
the other Parallel Link members.
7. Stop offered load. Wait 30 seconds for queues to drain.
Restart Offered Load.
8. Restore SONET on Tester's Neighbor Interface connected to
DUT's Parallel Link member interface.
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9. Measure Restoration Convergence Time [2] as DUT detects the
link up event and converges IGP routes and some distribution
of traffic over the restored Parallel Link member.
Results
The measured IGP Convergence time is influenced by the Local
SONET indication, Tree Build Time, and Hardware Update Time.
5. Security Considerations
Documents of this type do not directly affect the security of
the Internet or corporate networks as long as benchmarking
is not performed on devices or systems connected to operating
networks.
6. References
[1] Poretsky, S., "Benchmarking Applicability for IGP
Convergence", draft-ietf-bmwg-igp-dataplane-conv-app-04, work
in progress, October 2004.
[2] Poretsky, S., Imhoff, B., "Benchmarking Terminology for IGP
Convergence", draft-ietf-bmwg-igp-dataplane-conv-term-04, work
in progress, October 2004
[3] Callon, R., "Use of OSI IS-IS for Routing in TCP/IP and Dual
Environments", RFC 1195, December 1990.
[4] Moy, J., "OSPF Version 2", RFC 2328, IETF, April 1998.
7. Author's Address
Scott Poretsky
Quarry Technologies
8 New England Executive Park
Burlington, MA 01803
USA
Phone: + 1 781 395 5090
EMail: sporetsky@quarrytech.com
Brent Imhoff
LightCore
USA
EMail: bimhoff@planetspork.com
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