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Keywords: multiprotocol label switching, mpmls forwarding devices
Network Working Group A. Akhter
Request for Comments: 5695 R. Asati
Category: Informational C. Pignataro
Cisco Systems
November 2009
MPLS Forwarding Benchmarking Methodology for IP Flows
Abstract
This document describes a methodology specific to the benchmarking
of Multiprotocol Label Switching (MPLS) forwarding devices, limited
to the most common MPLS packet forwarding scenarios and delay
measurements for each, considering IP flows. It builds upon the
tenets set forth in RFC 2544, RFC 1242, and other IETF Benchmarking
Methodology Working Group (BMWG) efforts. This document seeks to
extend these efforts to the MPLS paradigm.
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (c) 2009 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
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
Akhter, et al. Informational [Page 1]
RFC 5695 MPLS Benchmarking Methodology November 2009
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction ....................................................2
2. Document Scope ..................................................3
3. Key Words To Reflect Requirements ...............................4
4. Test Methodology ................................................4
4.1. Test Considerations ........................................5
4.1.1. Abbreviations Used ..................................5
4.1.2. IGP Support .........................................6
4.1.3. Label Distribution Support ..........................6
4.1.4. Frame Formats .......................................7
4.1.5. Frame Sizes .........................................9
4.1.6. Time-to-Live (TTL) or Hop Limit ....................12
4.1.7. Trial Duration .....................................12
4.1.8. Traffic Verification ...............................12
4.1.9. Address Resolution and Dynamic Protocol State ......13
5. Reporting Format ...............................................13
6. MPLS Forwarding Benchmarking Tests .............................14
6.1. Throughput ................................................15
6.1.1. Throughput for MPLS Label Push .....................16
6.1.2. Throughput for MPLS Label Swap .....................17
6.1.3. Throughput for MPLS Label Pop (Unlabeled) ..........18
6.1.4. Throughput for MPLS Label Pop (Aggregate) ..........19
6.1.5. Throughput for MPLS Label Pop (PHP) ................20
6.2. Latency Measurement .......................................21
6.3. Frame-Loss Rate (FLR) Measurement .........................22
6.4. System Recovery ...........................................23
6.5. Reset .....................................................23
7. Security Considerations ........................................25
8. Acknowledgement ................................................25
9. References .....................................................25
9.1. Normative References ......................................25
9.2. Informative References ....................................26
1. Introduction
Over the past several years, there has been an increase in the use of
MPLS as a forwarding architecture in new and existing network
designs. MPLS, defined in [RFC3031], is a foundation technology and
the basis for many advanced technologies such as Layer 3 MPLS VPNs,
Layer 2 MPLS VPNs, and MPLS Traffic Engineering.
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However, there is no standard method defined to compare and contrast
the foundational MPLS packet forwarding capabilities of network
devices. This document proposes a methodology using common criteria
(such as throughput, latency, frame-loss rate, system recovery,
reset, etc.) to evaluate MPLS forwarding of any implementation.
2. Document Scope
The benchmarking methodology principles outlined in RFC 2544
[RFC2544] are independent of forwarding techniques; however, they
don't fully address MPLS benchmarking. The workload on network
forwarding device resources that MPLS forwarding places is different
from that of IP forwarding; therefore, MPLS forwarding benchmarking
specifics are desired.
The purpose of this document is to describe a methodology specific to
the benchmarking of MPLS forwarding devices. The methods described
are limited in scope to the most common MPLS packet forwarding
scenarios and corresponding performance measurements in a laboratory
setting. It builds upon the tenets set forth in RFC 2544 [RFC2544],
RFC 1242 [RFC1242], and other IETF Benchmarking Methodology Working
Group (BMWG) efforts. In other words, this document is not a
replacement for, but a complement to, RFC 2544.
This document focuses on the MPLS label stack [RFC3032] that has only
one entry, as it is the fundamental of MPLS forwarding. It is
expected that future documents may cover the benchmarking of MPLS
applications such as Layer 3 VPN (L3VPN) [RFC4364], Layer 2 VPN
(L2VPN) [RFC4664], Fast ReRoute [RFC4090], etc., which require more
than one entry in the MPLS label stack.
Moreover, to address the majority of current deployments' needs, this
document focuses on having IP packets as the MPLS payload. In other
words, label distribution for IP Forwarding Equivalence Class (FEC)
[RFC3031] is prescribed (see Section 4.1.3) by this document. It is
expected that future documents may focus on having non-IP packets as
the MPLS payload.
Note that the presence of an MPLS label stack does not require the
length of MPLS payload (which is an IP packet, per this document) to
be changed; hence, the effective maximum size of a frame can increase
by Z octets (where Z = 4 x number of label stack entries), as
observed in current deployments. This document focuses on
benchmarking such a scenario.
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3. Key Words To Reflect 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, RFC 2119
[RFC2119]. RFC 2119 defines the use of these key words to help make
the intent of Standards Track documents as clear as possible. While
this document uses these keywords, this document is not a Standards
Track document.
4. Test Methodology
The set of methodologies described in this document will use the
topology described in this section. An effort has been made to
exclude superfluous equipment needs such that each test can be
carried out with a minimal number of devices. Figure 1 illustrates
the sample topology in which the Device Under Test (DUT) is connected
to the test ports on the test tool in accord with Figure 1 of RFC
2544.
+-----------------+
+---------+ | | +---------+
| Test | | | | Test |
| Port A1 +-----+ DA1 DB1 +-----+ Port B1 |
+---------+ | | +---------+
+---------+ | DUT | +---------+
| Test | | | | Test |
| Port A2 +-----+ DA2 DB2 +-----+ Port B2 |
+---------+ | | +---------+
... | ... ... | ...
+---------+ | | +---------+
| Test | | | | Test |
| Port Ap +-----+ DAp DBp +-----+ Port Bp |
+---------+ +-----------------+ +---------+
Figure 1: Topology for MPLS Forwarding Benchmarking
A represents a Tx-side Module of the test tool, whereas B represents
an Rx-side Module of the same test tool. Of course, the suffixed
numbers (1, 2, ..., p) represent ports on a Module.
Similarly, DA represents an Rx-side Module of the DUT, whereas DB
represents a Tx-side Module. The suffixed numbers (1, 2, ..., p)
represent ports on a Module.
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p = the number of {DA, DB} pair ports on the DUT. It is determined
by the maximum unidirectional forwarding throughput of the DUT and
the load capacity of the port media (e.g., interface) connecting the
DUT to the test tool.
For example, if the DUT's maximum forwarding throughput is 100 frames
per second (fps) and the load capacity of the port media (e.g.,
interface) is 50 fps, then p >= 2 is needed to sufficiently test the
maximum frame forwarding.
The exact throughput is a measured quantity obtained through testing.
Throughput may vary depending on the number of ports used and other
factors. The number of ports (p) used SHOULD be reported. Please
see "Test Setup" in Section 6. Following Figure 1 from Section 6 of
RFC 2544 is recommended.
4.1. Test Considerations
This methodology assumes a full-duplex, uniform medium topology. The
medium used MUST be reported in each test result. Issues regarding
mixed transmission media, speed mismatches, media header differences,
etc., are not under consideration. Traffic affecting features such
as Flow control, Quality of Service (QoS), Graceful Restart, etc.
MUST be disabled, unless explicitly requested in the test case.
Additionally, any non-essential traffic MUST also be avoided.
4.1.1. Abbreviations Used
The terms used in this document remain consistent with those defined
in "Benchmarking Terminology for Network Interconnect Devices" RFC
1242 [RFC1242]. This terminology SHOULD be consulted before using or
applying the recommendations of this document.
Please refer to Figure 1 for a topology view of the network. The
following abbreviations are used in this document:
M := Module on a device (i.e., Line-Card or Slot; could be A or B)
p := Port number (i.e., port on the Module; could be 1, 2, etc.)
RN := Remote Network (i.e., network that is reachable via a port of a
module; could be B1RN1 or B2RN5 to mean the first network reachable
via port 1 of module B, e.g., B1, or the fifth network reachable via
port 2 of module B, etc.). RN is considered to be the IP Prefix FEC
from the MPLS perspective.
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4.1.2. IGP Support
It is RECOMMENDED that all of the ports (A1, DA1, DB1, and A2) on the
DUT and test tool support a dynamic Interior Gateway Protocol (IGP)
for routing such as IS-IS, OSPF, RIP, etc. Furthermore, there are
testing considerations in this document that the device be able to
provide a stable control plane during heavy forwarding workloads. In
particular, the procedures defined in Section 11.3 of RFC 2544 must
be followed. This is to ensure that control plane instability during
load conditions is not the contributing factor towards frame
forwarding performance.
The route distribution method (OSPF, IS-IS, Enhanced Interior Gateway
Routing Protocol (EIGRP), RIP, Static, etc.), if used, MUST be
reported. Furthermore, if any specific configuration is used to
maintain control plane stability during the test (i.e., Control Plane
Protection, Control Plane Rate Limiting, etc.), then it MUST also be
reported.
4.1.3. Label Distribution Support
The DUT and test tool must support at least one protocol for
exchanging MPLS label/FEC bindings for Prefix Forwarding Equivalence
Class (FEC) [RFC3031]. The DUT and test tool MUST be capable of
learning and advertising MPLS label/FEC bindings via the chosen
protocol(s) and use them during packet forwarding all the time
(including when the label/FEC bindings change). The most commonly
used protocols are Label Distribution Protocol (LDP) [RFC5036],
Resource Reservation Protocol-Traffic Engineering (RSVP-TE)
[RFC3209], and Border Gateway Protocol (BGP) [RFC3107].
All of the ports (A1, DA1, DB1, B1, etc.) either on the DUT or the
test tool used in the testing SHOULD support LDP, RSVP-TE, and BGP
for IPv4 or IPv6 Prefix Forwarding Equivalence Classes (FECs).
Static labels SHOULD NOT be used to establish the MPLS label switched
paths (LSPs), unless specified explicitly by the test case.
This is because the use of a static label is quite uncommon in the
production networks.
The IPv4 and IPv6 Explicit NULL labels (label values 0 and 2) are
sometimes used to identify the payload of an MPLS packet on an LSP
[RFC3032]. Explicit NULL labels are not used in the tests described
in this document because the tests are limited to the use of no more
than one non-reserved MPLS label in the label stack of all packets
to, from, or through the DUT.
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4.1.4. Frame Formats
This section explains the frame formats for IP and MPLS packets
(Section 4.1.4.1), the usage of IP as the mandatory Layer 3 protocol
and as the MPLS packet payload (Section 4.1.4.2), change in frame
format during forwarding (Section 4.1.4.3), and recommended frame
formats for the MPLS benchmarking (Section 4.1.4.4).
4.1.4.1. Frame Format for IP versus MPLS
A test frame carrying an IP packet is illustrated in Figure 2 below.
Note that RFC 2544 [RFC2544] prescribes using such a frame as the
test frame over the chosen Layer 2 media.
+---------+--------------+-----------------------+
| Layer 2 | Layer 3 = IP | Layer 4 = UDP |
+---------+--------------+-----------------------+
Figure 2: Frame Format for IP Packets
Unlike a test frame carrying an IP packet, a test frame carrying an
MPLS packet contains an "MPLS label stack" [RFC3032] immediately
after the Layer 2 header (and before the IP header, if any) as
illustrated in Figure 3 below.
+---------+-------+--------------+-----------------------+
| Layer 2 | MPLS | Layer 3 = IP | Layer 4 = UDP |
+---------+-------+--------------+-----------------------+
Figure 3: Frame Format for MPLS Packets
The MPLS label stack is represented as a sequence of "label stack
entries", where each label stack entry is 4 octets, as illustrated in
Figure 1 of [RFC3032]. This document requires exactly one entry in
the MPLS label stack in an MPLS packet.
MPLS label values used in any test case MUST be outside the reserved
label value (0-15) unless stated otherwise.
4.1.4.2. MPLS Packet Payload
This document prescribes using an IP packet as the MPLS payload (as
illustrated in Figure 3 above). Generically speaking, this document
mandates the test frame to include IP (either IPv4 or IPv6) as the
Layer 3 protocol, in accord with Section 8 of [RFC2544] and
independent of the MPLS label stack presence, for three reasons:
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1. This enables using IP Prefix Forwarding Equivalence Class (FEC)
[RFC3031], which is a must for every MPLS network.
2. This provides the foundation or baseline for the benchmarking of
various other MPLS applications such as L3VPN, L2VPN, TE-FRR, etc.
3. This enables leveraging RFC 2544 [RFC2544], which prescribes using
IP packets with UDP data as the test frames. (Note that [RFC5180]
also uses this prescription for IPv6 benchmarking).
While the usage of non-IP payloads is possible, it requires an MPLS
application, e.g., L2VPN, whose benchmarking may be covered in
separate BMWG documents (MPLS L2VPN Benchmarking, for example) in the
future. This is also explained in Section 2.
4.1.4.3. Change in Frame Format Due to MPLS Push and Pop
A frame carrying an IP or MPLS packet may go through any of the three
MPLS forwarding operations: label push (or LSP Ingress), label swap,
and label pop (or LSP Egress), as defined in [RFC3031]. It is
important to understand the change of the frame format from IP to
MPLS or vice versa depending on the forwarding operation.
In a label push (or LSP Ingress) operation, the DUT receives a frame
containing an IP packet and forwards a frame containing an MPLS
packet if the corresponding forwarding lookup for the IP destination
points to a label push operation.
In a label swap operation, the DUT receives a frame containing an
MPLS packet and forwards a frame containing an MPLS packet if the
corresponding forwarding lookup for the label value points to a label
swap operation.
In a label pop (or LSP Egress) operation, the DUT receives a frame
containing an MPLS packet and forwards a frame containing an IP
packet if the corresponding forwarding lookup for the label value
points to a label pop operation.
4.1.4.4. Frame Formats to Be Used for Benchmarking
This document prescribes using two test frame formats to
appropriately test the forwarding operations: (1) Frame format for IP
and (2) Frame format for MPLS. Both formats are explained in Section
4.1.4.1. Additionally, the format of the test frame may change
depending on the forwarding operation.
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1. For test cases involving the label push operation, the test tool
must use the frame format for IP packets (Figure 2) to send the
test frames to the DUT, and must use the frame format for MPLS
packets (Figure 3) to receive the test frames from the DUT.
2. For test cases involving the label swap operation, the test tool
must use the frame format for MPLS packets (Figure 3) to send the
test frames to the DUT, and must use the frame format for MPLS
packets (Figure 3) to receive the test frames from the DUT.
3. For test cases involving the label pop operation, the test tool
must use the frame format for MPLS packets (Figure 3) to send the
test frames to the DUT, and must use the frame format for IP
packets (Figure 2) to receive the test frames from the DUT.
4.1.5. Frame Sizes
Two types of port media are commonly deployed: Ethernet and POS
(Packet Over Synchronous Optical Network). This section identifies
the frame sizes that SHOULD be used for each media type, if supported
by the DUT; Section 4.1.5.1 covers Ethernet and Section 4.1.5.2
covers POS.
First, it is important to note the possible increase in frame size
due to the presence of an MPLS label stack in the frame (as explained
in Section 4.1.4.3).
As observed in the current deployments, presence of an MPLS label
stack in a Layer 2 frame is assumed to be transparent to Layer3=IP,
which continues to follow the conventional maximum frame payload size
[RFC3032] (1500 octets for Ethernet, say). This means that the
effective maximum frame payload size [RFC3032] of the resulting Layer
2 frame is Z octets more than the conventional maximum frame payload
size, where Z = 4 x number of entries in the label stack.
Hence, to ensure successful delivery of Layer 2 frames carrying MPLS
packets and realistic benchmarking, it is RECOMMENDED to set the
media MTU value to the effective maximum frame payload size
[RFC3032], which equals Z octets + conventional maximum frame payload
size. It is expected that such a change in the media MTU value only
impacts the effective Maximum Frame Payload Size for MPLS packets,
but not for IP packets.
Note that this document requires exactly a single entry in the MPLS
label stack in an MPLS packet. In other words, the depth of the
label stack is set to one, e.g., Z = 4 x 1 = 4 octets. Furthermore,
in accord with Sections 9 and 9.1 of RFC 2544, this document
prescribes that each test case is run with different (Layer 2) frame
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sizes in different trials. Additionally, results MAY also be
collected with multiple simultaneous frame sizes (sometimes referred
to as an Interactive Multimodal Information Extraction (IMIX) to
simulate real network traffic according to the frame size ordering
and usage). There is no standard for mixtures of frame sizes, and
the results are subject to wide interpretation (see Section 18 of RFC
2544). When running trials using multiple simultaneous frame sizes,
the DUT configuration MUST remain the same.
4.1.5.1. Frame Sizes To Be Used on Ethernet Media
Ethernet media, in all its types, has become the most commonly
deployed port media in MPLS networks. If any test case execution
(such as the Label Push case) requires the test tool to send (or
receive) a Layer 2 frame containing an IP packet, then the following
frame sizes SHOULD be used for benchmarking over Ethernet media: 64,
128, 256, 512, 1024, 1280, and 1518 octets. This is in-line with
Sections 9 and 9.1 of RFC 2544. Figure 4 illustrates the header
sizes for an untagged Ethernet frame containing an IP payload (per
RFC 2544).
<----------------64-1518B------------------------>
<--18B---><-----------46-1500B------------------->
+---------+---------+----------------------------+
| Layer 2 | Layer 3 | Layer 4 (and higher) |
+---------+---------+----------------------------+
Figure 4: Frame Size for Label Push Cases
Note 1: The 64- and 1518-octet frame size represents the minimum
and maximum length of an untagged Ethernet frame, as per IEEE
802.3 [IEE8023]. A frame size commonly used in operational
environments may range from 68 to 1522 octets, which are the
minimum and maximum lengths of a single VLAN-tagged frame, as per
IEEE 802.1D [IEE8021].
Note 2: While jumbo frames are outside the scope of the 802.3 IEEE
standard, tests SHOULD be executed with the frame sizes that are
supported by the DUT. Examples of commonly used jumbo (Ethernet)
frame sizes are: 4096, 8192, and 9216 octets.
If any test case execution (such as Label Swap and Label Pop cases)
requires the test tool to transmit (or receive) a Layer 2 frame
containing an MPLS packet, then the untagged Layer 2 frame must
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include an additional 4 octets for the MPLS header, resulting in the
following frame sizes to be used for benchmarking over Ethernet
media: 68, 132, 260, 516, 1028, 1284, and 1522 octets. Figure 5
illustrates the header sizes for an untagged Ethernet frame
containing an MPLS packet.
<------------------68-1522B------------------------------>
<--18B---><--4B--><-----------46-1500B------------------->
+---------+-------+---------+----------------------------+
| Layer 2 | MPLS | Layer 3 | Layer 4 (and higher) |
+---------+-------+---------+----------------------------+
Figure 5: Frame Size for Label Swap and Pop Cases
Note: The Media MTU on the link between the test tool and the DUT
must be changed, if needed, to accommodate the effective maximum
frame payload size [RFC3032] resulting from adding an MPLS label
stack to the IP packet. As clarified in Section 3.1 of RFC 3032,
most Layer 2 media drivers are capable of sending and receiving
Layer 2 frames with effective maximum frame payload size. Many
vendors also allow the Media MTU to be changed for MPLS, without
changing it for IP. The recommended link MTU value for MPLS is Z
octets more than the conventional maximum frame payload size
[RFC3032] (for example, the conventional maximum frame payload
size for Ethernet is 1500 octets). This document prescribes Z=4
octets. If a vendor DUT doesn't allow such an MTU change, then
the benchmarking cannot be performed for the true maximum frame
payload size [RFC3032] and this must be reported.
4.1.5.2. Frame Sizes to Be Used on POS Media
Packet over SONET (POS) media are commonly used for edge uplinks and
high-bandwidth core links. POS may use one of various encapsulations
techniques (such as PPP, High-Level Data Link Control (HDLC), Frame
Relay, etc.), resulting in the Layer 2 header (~4 octets) being less
than that of the Ethernet media. The rest of the frame format
(illustrated in Figures 2 and 3) remains pretty much unchanged.
If the MPLS forwarding characterization of POS interfaces on the DUT
is desired, then the following frame sizes SHOULD be used:
Label Push test cases: 47, 64, 128, 256, 512, 1024,
1280, 1518, 2048, and 4096 octets.
Label Swap and Pop test cases: 51, 68, 132, 260, 516, 1028,
1284, 1522, 2052, and 4100 octets.
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4.1.6. Time-to-Live (TTL) or Hop Limit
The TTL value in the frame header MUST be large enough to allow a TTL
decrement to happen and still be forwarded through the DUT. The
aforementioned TTL field may be referring to either the MPLS TTL,
IPv4 TTL, or IPv6 Hop Limit depending on the exact forwarding
scenario under evaluation.
If TTL/Hop Limit decrement, as specified in [RFC3443], is a
configurable option on the DUT, the setting SHOULD be reported.
4.1.7. Trial Duration
Unless otherwise specified, the test portion of each trial SHOULD be
no less than 30 seconds when static routing is in place, and no less
than 200 seconds when a dynamic routing protocol and LDP (default LDP
holddown timer is 180 seconds) are being used. If the holddown timer
default value is changed, then it should be reported and the trial
duration should still be 20 seconds more than the holddown timer
value.
The longer trial time used for dynamic routing protocols is to verify
that the DUT is able to maintain a stable control plane when the
data-forwarding plane is under stress.
4.1.8. Traffic Verification
In all cases, sent traffic MUST be accounted for, whether it was
received on the wrong port, the correct port, or not received at all.
Specifically, traffic loss (also referred to as frame loss) is
defined as the traffic (i.e., one or more frames) not received where
expected (i.e., received on the incorrect port, or received with
incorrect Layer 2 or above header information, etc.). In addition,
the presence or absence of the MPLS label stack, every field value
inside the label stack, if present, ethertype (0x8847 or 0x8848
versus 0x0800 or 0x86DD), frame sequencing, and frame check sequence
(FCS) MUST be verified in the received frame.
Many test tools may, by default, only verify that they have received
the embedded signature on the receive side. However, for MPLS header
presence verification, some tests will require the MPLS header to be
pushed while others will require a swap or pop. Hence, this document
requires the test tool to verify the MPLS stack depth. An even
greater level of verification would be to check if the correct label
was pushed. However, some test tools are not capable of checking the
received label value for correctness. Test tools SHOULD verify that
the packets received carry the expected MPLS label.
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4.1.9. Address Resolution and Dynamic Protocol State
If a test setup utilizes any dynamic protocols for control plane
signaling (e.g., ARP, PPP (including MPLSCP), OSPF, LDP, etc.), then
all state for the protocols MUST be pre-established before the test
case is executed (i.e., packet streams are started).
5. Reporting Format
For each test case, it is RECOMMENDED that the following variables be
reported in addition to the specific parameters requested by the test
case:
Parameter Units or Examples
Prefix Forwarding Equivalence IPv4, IPv6, Both
Class (FEC)
Label Distribution Protocol LDP, RSVP-TE, BGP (or
combinations)
MPLS Forwarding Operation Push, Swap, Pop
IGP ISIS, OSPF, EIGRP, RIP,
static.
Throughput Frames per second and
bits per second
Port Media GigE (Gigabit Ethernet),
POS, ATM, etc.
Port Speed 1 gbps, 100 Mbps, etc.
Interface Encapsulation Ethernet, Ethernet
VLAN, PPP, HDLC, etc.
Frame Size (Section 4.1.5) Octets
p (Number of {DA, DB} pair 1,2, etc.
ports per Figure 1)
The individual test cases may have additional reporting requirements
that may refer to other RFCs.
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6. MPLS Forwarding Benchmarking Tests
MPLS is a different forwarding paradigm from IP. Unlike IP packets
and IP forwarding, an MPLS packet may contain more than one MPLS
header and may go through one of three forwarding operations: push
(or LSP Ingress), swap, or pop (or LSP Egress), as defined in
[RFC3031]. Such characteristics desire further granularity in MPLS
forwarding benchmarking than those described in RFC 2544. Thus, the
benchmarking may include, but is not limited to:
1. Throughput
2. Latency
3. Frame-Loss Rate
4. System Recovery
5. Reset
6. MPLS TC (previously known as EXP [RFC5462]) field Operations
(including explicit-null cases)
7. Negative Scenarios (TTL expiry, etc.)
8. Multicast
However, this document focuses only on the first five categories,
inline with the spirit of RFC 2544. All the benchmarking test cases
described in this document are expected to, at a minimum, follow the
"Test Setup" and "Test Procedure" below:
Test Setup
Referring to Figure 1, a single port (p = 1) on both A and B
Modules SHOULD be used. However, if the forwarding throughput of
the DUT is more than that of the media rate of a single port, then
additional ports on A and B Modules MUST be enabled as follows: if
the DUT can be configured with the A and B ports so as to exceed
the DUT's forwarding throughput without overloading any B ports,
then those MUST be enabled; if, on the other hand, the DUT's
forwarding throughput capacity is greater than what can be
achieved enabling all ports, then all An and Bn ports MUST be
enabled. In the case where more than one A and B port is enabled,
the procedures described in Section 16 of RFC 2544 must be
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followed to accommodate the multi-port scenario. The frame
formats transmitted and received must be in accord with Sections
4.1.4.3 and 4.1.4.4, and frame sizes must be in accord with
Section 4.1.5.
Note: The test tool must be configured not to advertise a prefix
or FEC to the DUT on more than one port. In other words, the DUT
must associate a FEC with one and only one DB port. The Equal
Cost Multi-Path (ECMP) behavior in MPLS networks uses heuristics
[RFC4928]; hence, the usage of ECMP is NOT permitted by this
document to ensure the deterministic forwarding behavior during
benchmarking.
Test Procedure
In accord with Section 26 of RFC 2544 [RFC2544], the traffic is
sent from test tool port(s) Ap to the DUT at a constant load for a
fixed-time interval, and is received from the DUT on test tool
port(s) Bp. As described in Section 4.1.4.3, the frame may
contain either an IP packet or an MPLS packet depending on the
test case need. Furthermore, the IP packet must be either an IPv4
or IPv6 packet, depending on whether the MPLS benchmarking is done
for IPv4 or IPv6.
If any frame loss is detected, then a new iteration is needed
where the offered load is decreased and the sender will transmit
again. An iterative search algorithm MUST be used to determine
the maximum offered frame rate with a zero frame loss.
This maximum offered frame rate that results in zero frame loss
through the DUT is defined as the Throughput in Section 3.17 of
[RFC1242] for that test case. Informally, this rate is referred
to as the No-Drop Rate (NDR).
Each iteration should involve varying the offered load of the
traffic, while keeping the other parameters (test duration, number
of ports, number of addresses, frame size, etc.) constant, until
the maximum rate at which none of the offered frames are dropped
is determined.
6.1. Throughput
This section contains the description of the tests that are related
to the characterization of a DUT's MPLS traffic forwarding.
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6.1.1. Throughput for MPLS Label Push
Objective
To obtain the DUT's Throughput (as per RFC 2544) during label push
or LSP Ingress forwarding operation (i.e., IP to MPLS).
Test Setup
In addition to the "Test Setup" described in Section 6, the test
tool must advertise the IP prefix(es), i.e., RNx (using a routing
protocol as per Section 4.1.2) and associated MPLS label-FEC
binding(s) (using a label distribution protocol as per Section
4.1.3) on its receive ports Bp to the DUT. The test tool may
learn the IP prefix(es) on its transmit ports Ap from the DUT.
MPLS and/or the label distribution protocol must be enabled only
on the test tool receive ports Bp and DUT transmit ports DBp.
Discussion
The DUT's MPLS forwarding table (also referred to as Incoming
Label Map (ILM) to Next Hop Label Forwarding Entry (NHLFE) mapping
table per Section 3.11 of [RFC3031]) must contain a non-reserved
MPLS label value as the outgoing label for each learned IP prefix
corresponding to the label-FEC binding, resulting in the DUT
performing the IP-to-MPLS forwarding operation. The test tool
must receive MPLS packets on receive ports Bp (from the DUT) with
the same label values that were advertised.
Procedure
Please see "Test Procedure" in Section 6. Additionally, the test
tool MUST send the frames containing IP packets (with the IP
destination belonging to the advertised IP prefix(es)) on transmit
ports Ap, and expect to receive frames containing MPLS packets on
receive ports Bp, as described in Section 4.1.4.4.
Reporting Format
The result should be reported as per Section 5 and RFC 2544.
Results for each test SHOULD be in the form of a table with a row
for each of the tested frame sizes. Additional columns SHOULD
include offered load and measured throughput.
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6.1.2. Throughput for MPLS Label Swap
Objective
To obtain the DUT's Throughput (as per RFC 2544) during label
swapping operation (i.e., MPLS-to-MPLS).
Test Setup
In addition to the setup described in Section 6, the test tool
must advertise IP prefix(es) (using a routing protocol as per
Section 4.1.2) and associated MPLS label-FEC bindings (using a
label distribution protocol as per Section 4.1.3) on the receive
ports Bp, and then learn the IP prefix(es) as well as the label-
FEC binding(s) on the transmit ports Ap. The test tool must use
the learned MPLS label values and learned IP prefix values in the
frames transmitted on ports Ap to the DUT.
MPLS and/or label distribution protocol must be enabled on the
test tool ports Bp and Ap, and the DUT ports DBp and DAp.
Discussion
The DUT's MPLS forwarding table (also referred to as ILM to NHLFE
mapping table per Section 3.11 of [RFC3031]) must contain non-
reserved MPLS label values as the outgoing and incoming labels for
the learned IP prefixes, resulting in an MPLS-to-MPLS forwarding
operation, e.g., label swap. The test tool must receive MPLS
packets on receive ports Bp (from the DUT) with the same label
values that were advertised using the label distribution protocol.
The received frames must contain the same number of MPLS headers
as those of transmitted frames.
Procedure
Please see "Test Procedure" in Section 6. Additionally, the test
tool must send frames containing MPLS packets (with the IP
destination belonging to the advertised IP prefix(es)) on its
transmit ports Ap, and expect to receive frames containing MPLS
packets on its receive ports Bp, as described in Section 4.1.4.4.
Reporting Format
The result should be reported as per Section 5 and RFC 2544.
Results for each test SHOULD be in the form of a table with a row
for each of the tested frame sizes.
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6.1.3. Throughput for MPLS Label Pop (Unlabeled)
Objective
To obtain the DUT's Throughput (as per RFC 2544) during label pop
or LSP Egress forwarding operation (i.e., MPLS-to-IP) using
"Unlabeled" outgoing label.
Test Setup
In addition to the setup described in Section 6, the test tool
must advertise the IP prefix(es) (using a routing protocol as per
Section 4.1.2) without any MPLS label-FEC bindings on the receive
ports Bp, and then learn the IP prefix(es) as well as the FEC-
label binding(s) on the transmit ports Ap. The test tool must use
the learned MPLS label values and learned IP prefix values in the
frames transmitted on ports Ap.
MPLS and/or label distribution protocol must be enabled only on
the test tool port(s) Ap and DUT port(s) DAp.
Discussion
The DUT's MPLS forwarding table (also referred to as ILM to NHLFE
mapping table per Section 3.11 of [RFC3031]) must contain an
Unlabeled outgoing label (also known as untagged) for the learned
IP prefix, resulting in an MPLS-to-IP forwarding operation.
Procedure
Please see "Test Procedure" in Section 6. Additionally, the test
tool must send frames containing MPLS packets on its transmit
ports Ap (with the IP destination belonging to the IP prefix(es)
advertised on port Bp), and expect to receive frames containing IP
packets on its receive ports Bp, as described in Section 4.1.4.4.
Reporting Format
The result should be reported as per Section 5 and RFC 2544.
Results for each test SHOULD be in the form of a table with a row
for each of the tested frame sizes.
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6.1.4. Throughput for MPLS Label Pop (Aggregate)
Objective
To obtain the DUT's Throughput (as per RFC 2544) during label pop
or LSP Egress forwarding operation (i.e., MPLS-to-IP) using the
"Aggregate" outgoing label [RFC3031].
Test Setup
In addition to the setup described in Section 6, the DUT must be
provisioned such that it allocates an aggregate outgoing label
(please see Section 3.20 in [RFC3031]) to an IP prefix, which
aggregates a set of prefixes learned on ports DBp from the test
tool. The prefix aggregation can be performed using BGP
aggregation (Section 9.2.2.2 of [RFC4271]), IGP aggregation
(Section 16.5 of [RFC2328]), etc.
The DUT must advertise the aggregating IP prefix along with the
associated MPLS label-FEC binding on ports DAp to the test tool.
The test tool then must use the learned MPLS label values and
learned IP prefix values in frames transmitted on ports Ap to the
DUT. The test tool must receive frames containing IP packets on
ports Bp from the DUT.
MPLS and/or label distribution protocol must be enabled only on
the test tool port(s) Ap and DUT port(s) DAp.
Discussion
The DUT's MPLS forwarding table (also referred to as ILM to NHLFE
mapping table per Section 3.11 of [RFC3031]) must contain an
aggregate outgoing label and IP forwarding table must contain a
valid entry for the learned prefix(es), resulting in MPLS-to-IP
forwarding operation (i.e., MPLS header removal followed by IP
lookup).
Procedure
Please see "Test Procedure" in Section 6. Additionally, the test
tool must send frames containing MPLS packets on its transmit
ports Ap (with IP destination belonging to the IP prefix(es)
advertised on port Bp), and expect to receive frames containing IP
packets on its receive ports Bp, as described in Section 4.1.4.4.
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Reporting Format
The result should be reported as per Section 5 and RFC 2544.
Results for each test SHOULD be in the form of a table with a row
for each of the tested frame sizes.
6.1.5. Throughput for MPLS Label Pop (PHP)
Objective
To obtain the DUT's Throughput (as per RFC 2544) during label pop
(i.e., MPLS-to-IP) or penultimate hop popping (PHP) using the
"imp-null" outgoing label.
Test Setup
In addition to the setup described in Section 6, the test tool
must be set up to advertise the IP prefix(es) (using a routing
protocol as per Section 4.1.2) and associated MPLS label-FEC
binding with a reserved MPLS label value = 3 (using a label
distribution protocol as per Section 4.1.3) on its receive ports
Bp. The test tool must learn the IP prefix(es) as well as the
MPLS label-FEC bindings on its transmit ports Ap. The test tool
then must use the learned MPLS label values and learned IP prefix
values in the frames transmitted on ports Ap to the DUT. The test
tool must receive frames containing IP packets on receive ports Bp
(from the DUT).
MPLS and/or label distribution protocol must be enabled on the
test tool ports Bp and Ap, and DUT ports DBp and DAp.
Discussion
This test case characterizes Penultimate Hop Popping (PHP), which
is described in RFC 3031.
The DUT's MPLS forwarding table (also referred to as ILM to NHLFE
mapping table per Section 3.11 of [RFC3031]) must contain a
reserved MPLS label value = 3 (e.g., pop or imp-null) as the
outgoing label for the learned prefix(es), resulting in MPLS-to-IP
forwarding operation.
This test case characterizes DUT's penultimate hop popping (PHP)
functionality.
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Procedure
Please see "Test Procedure" in Section 6. Additionally, the test
tool must send frames containing MPLS packets on its transmit
ports Ap (with IP destination belonging to advertised IP
prefix(es)), and expect to receive frames containing IP packets on
its receive ports Bp, as described in Section 4.1.4.4.
Reporting Format
The result should be reported as per Section 5 and RFC 2544.
Results for each test SHOULD be in the form of a table with a row
for each of the tested frame sizes.
6.2. Latency Measurement
Latency measurement measures the time taken by the DUT to forward the
MPLS packet during various MPLS switching paths such as IP-to-MPLS,
MPLS-to-MPLS, or MPLS-to-IP involving an MPLS label stack.
Objective
To obtain the average latency induced by the DUT during MPLS
packet forwarding for each of five forwarding operations.
Test Setup
Follow the "Test Setup" guidelines established for each of the
five MPLS forwarding operations in Sections 6.1.1 (for IP-to-
MPLS), 6.1.2 (for MPLS-to-MPLS), 6.1.3 (for MPLS-to-IP Unlabeled),
6.1.4 (for MPLS-to-IP Aggregate), and 6.1.5 (for MPLS-to-IP PHP),
one by one.
Procedure
Please refer to Section 26.2 in RFC 2544 in addition to following
the associated procedure for each MPLS forwarding operation in
accord with the test setup described earlier:
IP-to-MPLS forwarding (Push) Section 6.1.1
MPLS-to-MPLS forwarding (Swap) Section 6.1.2
MPLS-to-IP forwarding (Pop) Section 6.1.3
MPLS-to-IP forwarding (Aggregate) Section 6.1.4
MPLS-to-IP forwarding (PHP) Section 6.1.5
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Reporting Format
The result should be reported as per Section 5 and RFC 2544.
6.3. Frame-Loss Rate (FLR) Measurement
Frame-Loss Rate (FLR) measurement measures the percentage of MPLS
frames that were not forwarded during various switching paths such as
IP-to-MPLS (push), MPLS-to-IP (swap), or MPLS-IP (pop) by the DUT
under overloaded state.
Please refer to RFC 2544, Section 26.3, for more details.
Objective
To obtain the frame-loss rate, as defined in RFC 1242, for each of
the three MPLS forwarding operations of a DUT, throughout the
range of input data rates and frame sizes.
Test Setup
Follow the "Test Setup" guidelines established for each of the
five MPLS forwarding operations in Sections 6.1.1 (for IP-to-
MPLS), 6.1.2 (for MPLS-to-MPLS), 6.1.3 (for MPLS-to-IP Unlabeled),
6.1.4 (for MPLS-to-IP Aggregate), and 6.1.5 (for MPLS-to-IP PHP),
one by one.
Procedure
Please refer to Section 26.3 of RFC 2544 [RFC2544] and follow the
associated procedure for each MPLS forwarding operation one-by-one
in accord with the test setup described earlier:
IP-to-MPLS forwarding (Push) Section 6.1.1
MPLS-to-MPLS forwarding (Swap) Section 6.1.2
MPLS-to-IP forwarding (Pop) Section 6.1.3
MPLS-to-IP forwarding (Aggregate) Section 6.1.4
MPLS-to-IP forwarding (PHP) Section 6.1.5
A misdirected frame, that is, a frame received on the wrong Bn, is
considered lost. If the test tool is capable of checking received
MPLS label values, a frame with the wrong MPLS label is considered
lost.
Reporting Format
The result should be reported as per Section 5 and RFC 2544.
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6.4. System Recovery
Objective
To characterize the speed at which a DUT recovers from an overload
condition.
Test Setup
Follow the "Test Setup" guidelines established for each of the
five MPLS forwarding operations in Sections 6.1.1 (for IP-to-
MPLS), 6.1.2 (for MPLS-to-MPLS), 6.1.3 (for MPLS-to-IP Unlabeled),
6.1.4 (for MPLS-to-IP Aggregate), and 6.1.5 (for MPLS-to-IP PHP),
one by one.
Procedure
Please refer to Section 26.5 of RFC 2544 and follow the associated
procedure for each MPLS forwarding operation in the referenced
sections one-by-one in accord with the test setup described
earlier:
IP-to-MPLS forwarding (Push) Section 6.1.1
MPLS-to-MPLS forwarding (Swap) Section 6.1.2
MPLS-to-IP forwarding (Pop) Section 6.1.3
MPLS-to-IP forwarding (Aggregate) Section 6.1.4
MPLS-to-IP forwarding (PHP) Section 6.1.5
Reporting Format
The result should be reported as per Section 5 and RFC 2544.
6.5. Reset
The "reset" aspects of benchmarking are described in [RFC2544], but
these procedures need to be clarified in order to ensure consistency.
This document does not specify the reset procedures. These need to
be addressed in a separate document and will more generally apply to
IP and MPLS test cases.
The text below describes the MPLS forwarding benchmarking-specific
setup that will have to be used in conjunction with the procedures
from the separate document to make this test case meaningful.
Objective
To characterize the speed at which a DUT recovers from a device or
software reset.
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Test Setup
Follow the "Test Setup" guidelines established for each of the
five MPLS forwarding operations in Sections 6.1.1 (for IP-to-
MPLS), 6.1.2 (for MPLS-to-MPLS), 6.1.3 (for MPLS-to-IP Unlabeled),
6.1.4 (for MPLS-to-IP Aggregate), and 6.1.5 (for MPLS-to-IP PHP),
one by one.
For this test case, the requirements of LDP and a routing protocol
are removed and replaced by static configurations. For the IP-to-
MPLS forwarding, static route configurations should be applied.
For the MPLS-to-MPLS and MPLS-to-IP, static label configurations
must be applied.
For this test, all Graceful Restart features MUST be disabled.
Discussion
This test case is intended to provide insight into how long an
MPLS device could take to be fully operational after any of the
reset events. It is quite likely that the time an IP/MPLS device
takes to become fully operational after any of the reset events
may be different from that of an IP-only device.
Modern devices now have many more reset options that were not
available when Section 26.6 of RFC 2544 was published. Moreover,
different reset events on modern devices may produce different
results, hence, needing clarity and consistency in reset
procedures beyond what's specified in RFC 2544.
Procedure
Please follow the procedure from the separate document for each
MPLS forwarding operation one-by-one:
IP-to-MPLS forwarding (Push) Section 6.1.1
MPLS-to-MPLS forwarding (Swap) Section 6.1.2
MPLS-to-IP forwarding (Pop) Section 6.1.3
MPLS-to-IP forwarding (Aggregate) Section 6.1.4
MPLS-to-IP forwarding (PHP) Section 6.1.5
Reporting Format
The result should be reported as per Section 5 and as per the
separate document.
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7. 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.
Furthermore, benchmarking is performed on a "black-box" basis,
relying solely on measurements observable external to the DUT/SUT
(System Under Test).
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.
There are no specific security considerations within the scope of
this document.
8. Acknowledgement
The authors would like to thank Mo Khalid, who motivated us to write
this document. We would like to thank Rodney Dunn, Chip Popoviciu,
Jeff Byzek, Jay Karthik, Rajiv Papneja, Samir Vapiwala, Silvija
Andrijic Dry, Scott Bradner, Al Morton, and Bill Cerveny for their
careful review and suggestions.
This document was originally prepared using 2-Word-v2.0.template.dot.
9. References
9.1. Normative References
[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.
[RFC1242] Bradner, S., "Benchmarking Terminology for Network
Interconnection Devices", RFC 1242, July 1991.
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RFC 5695 MPLS Benchmarking Methodology November 2009
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[RFC3032] Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
Encoding", RFC 3032, January 2001.
[RFC3107] Rekhter, Y. and E. Rosen, "Carrying Label Information in
BGP-4", RFC 3107, May 2001.
[RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed.,
"LDP Specification", RFC 5036, October 2007.
9.2. Informative References
[RFC5180] Popoviciu, C., Hamza, A., Van de Velde, G., and D.
Dugatkin, "IPv6 Benchmarking Methodology for Network
Interconnect Devices", RFC 5180, May 2008.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border
Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC4664] Andersson, L., Ed., and E. Rosen, Ed., "Framework for Layer
2 Virtual Private Networks (L2VPNs)", RFC 4664, September
2006.
[IEE8021] Mick Seaman (editor), "IEEE Std 802.1D-2004, MAC Bridges",
Feb 2004.
[IEE8023] LAN/MAN Standards Committee of the IEEE Computer Society,
"IEEE Std 802.3as-2006, Part 3: Carrier Sense Multiple
Access with Collision Detection (CSMA/CD) Access Method and
Physical Layer Specifications, Amendment 3: Frame format
extensions", Nov 2006.
[RFC3443] Agarwal, P. and B. Akyol, "Time To Live (TTL) Processing in
Multi-Protocol Label Switching (MPLS) Networks", RFC 3443,
January 2003.
Akhter, et al. Informational [Page 26]
RFC 5695 MPLS Benchmarking Methodology November 2009
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching
(MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic
Class" Field", RFC 5462, February 2009.
[RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal
Cost Multipath Treatment in MPLS Networks", BCP 128, RFC
4928, June 2007.
[RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005.
Authors' Addresses
Aamer Akhter
Cisco Systems
7025 Kit Creek Road
RTP, NC 27709
USA
EMail: aakhter@cisco.com
Rajiv Asati
Cisco Systems
7025 Kit Creek Road
RTP, NC 27709
USA
EMail: rajiva@cisco.com
Carlos Pignataro
Cisco Systems
7200-12 Kit Creek Road
RTP, NC 27709
USA
EMail: cpignata@cisco.com
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