Network Working Group W. Cerveny
Internet-Draft Arbor Networks
Intended status: Informational R. Bonica
Expires: March 26, 2017 R. Thomas
Juniper Networks
September 22, 2016
Benchmarking The Neighbor Discovery Protocol
draft-ietf-bmwg-ipv6-nd-03
Abstract
This document provides benchmarking procedures for Neighbor Discovery
Protocol (NDP). It also proposes metrics by which an NDP
implementation's scaling capabilities can be measured.
Requirements Language
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].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 26, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Test Setup . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Device Under Test (DUT) . . . . . . . . . . . . . . . . . 4
2.1.1. Interfaces . . . . . . . . . . . . . . . . . . . . . 4
2.1.2. Neighbor Discovery Protocol (NDP) . . . . . . . . . . 4
2.1.3. Routing . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Tester . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.1. Interfaces . . . . . . . . . . . . . . . . . . . . . 5
2.2.2. Neighbor Discovery Protocol (NDP) . . . . . . . . . . 6
2.2.3. Routing . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.4. Test Traffic . . . . . . . . . . . . . . . . . . . . 6
2.2.5. Counters . . . . . . . . . . . . . . . . . . . . . . 7
3. Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Baseline Test . . . . . . . . . . . . . . . . . . . . . . 8
3.1.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 8
3.1.2. Results . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Scaling Test . . . . . . . . . . . . . . . . . . . . . . 9
3.2.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 9
3.2.2. Results . . . . . . . . . . . . . . . . . . . . . . . 10
4. Measurements Explicitly Excluded . . . . . . . . . . . . . . 11
4.1. DUT CPU Utilization . . . . . . . . . . . . . . . . . . . 11
4.2. Malformed Packets . . . . . . . . . . . . . . . . . . . . 11
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12
8. Normative References . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
When an IPv6 node forwards a packet, it executes the following
procedure:
o Identify the IPv6 next-hop (i.e., the next IPv6 node that the
packet traverses on route to its ultimate destination)
o Query a local Neighbor Cache (NC) to determine the IPv6 next-hop's
link-layer address
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o Encapsulate the packet in a link-layer header. The link-layer
header includes the IPv6 next-hop's link-layer address
o Forward the packet to the IPv6 next-hop
IPv6 nodes use the Neighbor Discovery Protocol (NDP) [RFC4861] to
maintain the NC. Operational experience [RFC6583] shows that when an
implementation cannot maintain a sufficiently complete NC, its
ability to forward packets is impaired.
NDP, like any other protocol, consumes processing, memory, and
bandwidth resources. Its ability to maintain a sufficiently complete
NC depends upon the availability of the above-mentioned resources.
This document provides benchmarking procedures for NDP. Benchmarking
procedures include a Baseline Test and an NDP Scaling Test. In both
tests, the Device Under Test (DUT) is an IPv6 router. Two physical
links (A and B) connect the DUT to a Tester. The Tester sends
traffic through Link A to the DUT. The DUT forwards that traffic,
through Link B, back to the Tester.
The above-mentioned traffic stream contains one or more interleaved
flows. An IPv6 Destination Address uniquely identifies each flow.
Or, said another way, every packet within a flow has the same IPv6
Destination Address.
In the Baseline Test, the traffic stream contains exactly one flow.
Because every packet in the stream has the same IPv6 Destination
Address, the DUT can forward the entire stream using exactly one NC
entry. NDP is exercised minimally and no packet loss should be
observed.
The NDP Scaling Test is identical to the Baseline Test, except that
the traffic stream contains many flows. In order to forward the
stream without loss, the DUT must maintain one NC entry for each
flow. If the DUT cannot maintain one NC entry for each flow, packet
loss will be observed and attributed to NDP scaling limitations.
This document proposes an NDP scaling metric, called NDP-MAX-
NEIGHBORS. NDP-MAX-NEIGHBORS is the maximum number of neighbors to
which an IPv6 node can send traffic during periods of high NDP
activity.
The procedures described herein reveal how many IPv6 neighbors an NDP
implementation can discover. They also provide a rough estimate of
the time required to discover those neighbors. However, that
estimate does not reflect the maximum rate at which the
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implementation can discover neighbors. Maximum rate discovery is a
topic for further exploration.
The test procedures described herein assume that on the DUT, NDP does
not compete for resources with other applications. When NDP
completes for resources, its scaling characteristics may not be
commensurate with those reported by the benchmarks described herein.
2. Test Setup
+---------------+ +-----------+
| | | |
| | Link A | Device |
| |------------>| Under |
| Tester | | Test |
| |<------------| (DUT) |
| | Link B | |
+---------------+ +-----------+
Figure 1: Test Setup
The DUT is an IPv6 router. The DUT is connected to a Tester by two
links (A and B). Link A capabilities must be identical to Link B
capabilities. For example, if the interface to Link A is a 10
Gigabit Ethernet port, the interface to Link B must also be a 10
Gigabit Ethernet port. Furthermore, Link A and Link B must be
lossless.
2.1. Device Under Test (DUT)
2.1.1. Interfaces
DUT interfaces are numbered as follows:
o Link A - 2001:2:0:0::2/64
o Link B- 2001:2:0:1::1/64
Both DUT interfaces should be configured with a 1500-byte MTU.
However, if they cannot support a 1500-byte MTU, they may be
configured with a 1280-byte MTU.
2.1.2. Neighbor Discovery Protocol (NDP)
NDP is enabled on both DUT interfaces. Therefore, the DUT emits both
solicited and unsolicited Router Advertisement (RA) messages. The
DUT emits an RA message at least once every 600 seconds and no more
frequently than once every 200 seconds.
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When the DUT sends an RA message, it includes the following
information:
o Router Lifetime - 1800 seconds
o Reachable Time - 0 seconds
o Retrans Time - 0 seconds
o Source Link Layer Address - Link layer address of DUT interface
The above-mentioned values are chosen because they are the default
values specified in RFC 4861.
NDP also manages the NC. Each NC entry represents an on-link
neighbor and is identified by the neighbor's on-link unicast IP
address. NC entries contain the neighbor's link-layer address, a
state variable, and several timers that are used by the Neighbor
Unreachability Detection (NUD) algorithm. Section 7.3 of RFC 4861
provides NUD details. On the DUT, NUD uses the protocol constants
defined in Section 10 of RFC 4861. As per these specifications, each
NC entry needs to be refreshed at least every 60 seconds. NDP
refreshes NC entries by exchanging Neighbor Solicitation (NS) and
Neighbor Advertisement (NA) messages.
No static NC entries are configured on the DUT.
2.1.3. Routing
The DUT maintains a direct route to 2001:2:0:0/64 through Link A. It
also maintains a direct route to 2001:2:0:1/64 through Link B. No
static routes or dynamic routing protocols are configured on the DUT.
2.2. Tester
2.2.1. Interfaces
Interfaces are numbered as follows:
o Link A - 2001:2:0:0::1/64
o Link B - Multiple addresses are configured on Link B. These
addresses are drawn sequentially from the 2001:2:0:1::/64 address
block. The first address is 2001:2:0:1::2/64. Subsequent
addresses are 2001:2:0:1::3/64, 2001:2:0:1::4/64,
2001:2:0:1::5/64, et cetera. The number of configured addresses
should be the expected value of NDP-MAX-NEIGHBORS times 1.1.
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Both Tester interfaces should be configured with a 1500-byte MTU.
However, if they cannot support a 1500-byte MTU, they may be
configured with a 1280-byte MTU.
2.2.2. Neighbor Discovery Protocol (NDP)
NDP is enabled on both Tester interfaces. Therefore, upon
initiation, the Tester sends Router Solicitation (RS) messages and
waits for Router Advertisement (RA) messages. The Tester also
exchanges Neighbor Solicitation (NS) and Neighbor Advertisement (NA)
messages with the DUT.
No static NC entries are configured on the Tester.
2.2.3. Routing
The Tester maintains a direct route to 2001:2:0:0/64 through Link A.
It also maintains a direct route to 2001:2:0:1/64 through Link B. No
static routes or dynamic routing protocols are configured on the
Tester.
2.2.4. Test Traffic
The Tester sends a stream test traffic through Link A to the DUT.
The test traffic stream contains one or more interleaved flows.
Flows are numbered 1 through N, sequentially.
Within each flow, each packet contains an IPv6 header and each IPv6
header contains the following information:
o Version - 6
o Traffic Class - 0
o Flow Label - 0
o Payload Length - 0
o Next Header - IPv6-NoNxt (59)
o Hop Limit - 255
o Source Address - 2001:2:0:0::1
o Destination Address - The first 64 bits of the Destination Address
are 2001:2:0:1::. The next 64 are uniquely associated with the
flow. Every packet in the first flow carries the Destination
address 2001:2:0:1::2. Every subsequent flow has an IP address
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one greater than the last (i.e., 2001:2:0:1::3, 2001:2:0:1::4,
etc.)
In order to avoid link congestion, test traffic is offered at a rate
not to exceed 50% of available link bandwidth. In order to avoid
burstiness and buffer occupancy, every packet in the stream is
exactly 40 bytes long (i.e., the length of an IPv6 header with no
IPv6 payload). Furthermore, the gap between packets is identical.
During the course of a test procedure, the number of flows that the
test stream contains may increase. When this occurs, the rate at
which test traffic is offered remains constant. For example, assume
that a test stream is offered at a rate of 1,000 packets per second.
This stream contains two flows, each contributing 500 packets per
second to the 1,000 packet per second aggregate. When a third stream
is added to the flow, all three streams must contribute 333 packets
per second in order to maintain the 1,000 packet per second limit.
(As in this example, rounding error is acceptable.)
The DUT attempts to forward every packet in the test stream through
Link B to the Tester. It does this because:
o Every packet in the test stream has a destination address drawn
from the 2001:2:0:1::/64 address block
o The DUT has a direct route to 2001:2:0:1/64 through Link B
2.2.5. Counters
For each address configured on the Tester interface to Link B, two
counters are configured. One counter, configured on the Tester
interface to Link A, increments when the Tester detects an outgoing
packet from the associated flow. The other counter, configured on
the Tester interface to Link B, increments when the Tester detects an
incoming packet from the associated flow. In order for a packet to
be associated with a flow, the following conditions must all be true:
o The IPv6 Destination Address must be that of the flow
o The IPv6 Next Header must be IPv6-NoNxt (59)
The following counters also are configured on both Tester Interfaces:
o RS packets sent
o RS packets received
o RA packets sent
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o RA packets received
o NS packets sent
o NS packets received
o NA packets sent
o NA packets received
o Total packets sent
o Total packets received
3. Tests
3.1. Baseline Test
The purpose of the Baseline Test is to ensure that the DUT can
forward every packet in the test stream, wThithout loss, when NDP is
minimally exercised and not operating near its scaling limit.
3.1.1. Procedure
o Reset all counters on the Tester
o Clear the NC on the DUT
o Set a timer to expire in 60 seconds
o Start the test stream with exactly one flow (i.e., IPv6
Destination Address equals 2001:2:0:1::2)
o Wait for either the timer to expire or the packets-received
counter associated with the flow to increment
o If the timer expires, stop the test stream and end the test
o If the packets-received counter increments, pause the traffic
stream, clear the timer, log the counters associated with the
flow, clear the counters associated with the flow, reset the timer
to expire in 1800 seconds and restart the traffic stream
o When the timer expires, stop the test stream, log all counters and
end the test
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3.1.2. Results
The two counters associated with the flow (packets-sent and packets-
received) must have equal values. If they do not, an error has
occurred. Because this error is likely to affect Scaling Test
results, the error must be corrected before the Scaling Test is
executed.
The log contains two counters (packets-sent and packets-received) for
the flow. If these values are identical, none of the initial packets
belonging to the flow were lost. However, if packets-sent is greater
than packets received, initial packets were lost. This loss of
initial packets is acceptable.
3.2. Scaling Test
The purpose of the Scaling Test is to discover the number of
neighbors to which an IPv6 node can send traffic during periods of
high NDP activity. We call this number NDP-MAX-NEIGHBORS.
3.2.1. Procedure
Execute the following procedure:
o Clear all counters on the Tester
o Clear the NC on the DUT
o Set a timer to expire in 60 seconds
o Start the test stream with exactly one flow (i.e., IPv6
Destination Address equals 2001:2:0:1::2)
o Wait for either the timer to expire or the packets-received
counter associated with the flow to increment
o If the timer expires, stop the test stream and end the test
o If the packets-received counter increments, proceed as described
below:
Execute the following procedure N times, starting at 2 and ending at
the number of expected value of NDP-MAX-NEIGHBORS time 1.1.
o Pause the test stream
o Clear the timer
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o Log the time, the value of N minus one, and the packets-sent and
packets-received counters associated with the previous flow (i.e.,
N minus one)
o Clear the packets-sent and packets-received counters associated
with the previous flow (i.e., N minus one)
o Reset the timer to expire in 60 seconds
o Add the next flow to the test stream (i.e.,IPv6 Destination
Address is a function of N)
o Restart the test stream
o Wait for either the timer to expire or the packets-received
counter associated with the new flow to increment
After the above described procedure had been executed N times, clear
the timer and reset it to expire in 1800 seconds. When the timer
expires, stop the stream, log all counters and end the test.
3.2.2. Results
The test report includes the following:
o A description of the DUT (make, model, processor, memory,
interfaces)
o Rate at which the Tester offers test traffic to the DUT (measured
in packets per second)
o A log that records the time at which each flow was introduced to
the test stream
o All counter values
NDP-MAX-NEIGHBORS is equal to the number of counter pairs where
packets-sent is equal to packets-recieved. Two counters are members
of a pair if they are both associated with the same IPv6 address. If
packets-sent is greater than zero and equal to packets-recieved for
every counter pair, the test should be repeated with a larger
expected value of NDP-MAX-NEIGHBORS.
If an implementation abides by the recommendation of RFC 6583, for
any given counter pair, packets-received will either be equal to zero
or packets-received.
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The log documents the time at which each flow was introduced to the
test stream. This log reveals the effect of NC size to the time
required to discover a new IPv6 neighbor.
The log contains two counters (packets-sent and packets-received) for
each flow. If these values are identical, none of the initial
packets belonging to the flow were lost. However, if packets-sent is
greater than packets received, initial packets were lost. This loss
of initial packets is acceptable.
4. Measurements Explicitly Excluded
These are measurements which aren't recommended because of the
itemized reasons below:
4.1. DUT CPU Utilization
This measurement relies on the DUT to provide utilization
information, which is subjective.
4.2. Malformed Packets
This benchmarking test is not intended to test DUT behavior in the
presence of malformed packets.
5. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
6. 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.
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Any implications for network security arising from the DUT/SUT SHOULD
be identical in the lab and in production networks.
7. Acknowledgements
Helpful comments and suggestions were offered by Al Morton, Joel
Jaeggli, Nalini Elkins, Scott Bradner, and Ram Krishnan, on the BMWG
e-mail list and at BMWG meetings. Precise grammatical corrections
and suggestions were offered by Ann Cerveny.
8. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC6583] Gashinsky, I., Jaeggli, J., and W. Kumari, "Operational
Neighbor Discovery Problems", RFC 6583,
DOI 10.17487/RFC6583, March 2012,
<http://www.rfc-editor.org/info/rfc6583>.
Authors' Addresses
Bill Cerveny
Arbor Networks
2727 South State Street
Ann Arbor, MI 48104
USA
Email: wcerveny@arbor.net
Ron Bonica
Juniper Networks
2251 Corporate Park Drive
Herndon, VA 20170
USA
Email: rbonica@juniper.net
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Reji Thomas
Juniper Networks
Elnath-Exora Business Park Survey
Bangalore, KA 560103
India
Email: rejithomas@juniper.net
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