Spirent Test Methodology MPLS Edition
SpirentCommunications
TestMethodologies
MPLS Edition
Introduction
Welcome to the MPLS Edition of Spirent Communications Test Methodologies, a series of resource
journals from Spirent Communications.
This volume contains a collection of vital test methodologies for Multi-Protocol Label Switching
(MPLS). These tests include LDP and RSVP-TE signaling protocols. Special applications and extensions
are also covered, such as RFC 2547bis and Martini VPNs.
MPLS is a rapidly evolving protocol. New draft standards are being written daily. As a result of these
dynamics, it is extremely challenging for network equipment manufacturers and service providers to
develop MPLS solutions. The test methodologies will help expedite the development and deployment
of MPLS equipment and networks.
To derive the maximum benefit from this book, download the test scripts associated with the
methodologies in this edition. The scripts can be accessed at <http://scdn.spirentcom.com>, which is
an online community for script writers and developers.
Thank you for your interest in Spirent Communications’ advanced testing solutions.
Best wishes with your MPLS testing!
Spirent Communications
http://www.spirentcom.com
Table of Contents
a73
LDP Forwarding Performance for Transit LSR (TM-0111) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
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LDP Forwarding Performance for Ingress LER (TM-0112) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
a73
LDP Forwarding Performance for Egress LER (TM-0113) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
a73
RSVP-TE Tunnel Establishment Stress Test (TM-0107) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
a73
RSVP-TE Forwarding Performance for Transit LSR (TM-0114) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
a73
RSVP-TE Forwarding Performance for Ingress LER (TM-0115) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
a73
RSVP-TE Forwarding Performance for Egress LER (TM-0116) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
a73
RSVP-TE Forwarding Performance During Tunnel Establishment (TM-0117) . . . . . . . . . . . . . . . . . 17
a73
BGP/MPLS VPN VRF Scalability (TM-0118) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
a73
Layer 2 Frames Over MPLS Scalability (TM-0119) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
a73
Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
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Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
1 Spirent Communications Test Methodologies • MPLS Network Testing
Legend
Spirent Communications Test Methodologies • MPLS Network Testing 2
TM-0111
LDP Forwarding
Performance for Transit LSR
a73
RFC 3036: LDP Specification
a73
RFC 2328: OSFP Version 2
Objective
This test verifies the device under test (DUT) is capable of creating LSP Tunnels as a Transit LSR
using LDP to distribute MPLS labels and correctly receiving and forwarding MPLS labeled packets
through the LSP.
Overview
An LSP is created with the DUT as the Transit LSR and two test ports, one acting as an Ingress LER
(Test Port A) and the other acting as an Egress LER (Test Port B). The Ingress LER will supply MPLS
labeled packets to the DUT using a label distributed by the DUT. The DUT will then re-label and
forward those packets to the Egress LER.
The Egress LER will receive the forwarded MPLS labeled packets and provide statistics. The number
of LSPs and/or data rate may be increased at each iteration until packet loss is observed. The system
under test (SUT) may consist of a single DUT or, optionally, a DUT with additional routers. If optional
routers are used so that the DUT and test ports are not directly connected, a route distribution
method (OSPF, IS-IS, static routes) may be necessary.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method
(OSPF, IS-IS, static routes).
2. Advertise a set number of destination routes from Test Port B.
3. Configure LDP label distribution method on the DUT and appropriate test ports as either
Downstream on Demand (DoD) or Downstream Unsolicited (DU).
3 Spirent Communications Test Methodologies • MPLS Network Testing
4. Depending on the method of label distribution (DoD, DU), the MPLS labels will be distributed by the
downstream node (DU) or the labels will be requested by upstream nodes (DoD).
5. Send MPLS labeled packets from the Ingress LER to all LSPs at a set rate.
6. Analyze MPLS labeled packets received at Egress LER.
7. If packet loss is observed:
a. Record traffic statistics and a Fail verdict.
b. End the test.
8. If no packet loss is observed:
a. Record traffic statistics and a Pass verdict.
9. To characterize router behavior, vary one of the following and return to Step 3. Otherwise, end the
test.
a. Number of LSPs.
b. Packet length.
c. Packet rate.
Test Parameters
a73
Number of LSPs.
a73
Packet length.
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Packet rate.
Test Outcome
Traffic and LDP statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 4
TM-0112
LDP Forwarding
Performance for Ingress LER
a73
RFC 3036: LDP Specification
a73
RFC 2328: OSFP Version 2
Objective
This test verifies the device under test (DUT) is capable of creating LSP Tunnels as an Ingress LER
using LDP, correctly attaching the label to received unlabeled packets and forwarding MPLS labeled
packets to the Egress LER.
Overview
An LSP is created with the DUT as the Ingress LER and Test Port B as the Egress LER. The source (Test
Port A) will supply unlabeled data packets to the DUT. The DUT will attach the appropriate label to the
packet and forward it through the LSP to the Egress LER. The Egress LER test port will receive the
forwarded MPLS labeled packets and provide statistics. The number of LSPs and/or data rate may be
increased at each iteration until packet loss is observed. The system under test (SUT) may consist of
a single DUT or, optionally, a DUT with additional routers. If optional routers are used so that the DUT
and test ports are not directly connected, a route distribution method (OSPF, IS-IS, static routes) may
be necessary.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method
(OSPF, IS-IS, static routes).
2. Advertise a set number of destination routes from Test Port B.
3. Configure LDP label distribution method on the DUT and appropriate test ports as either
Downstream on Demand (DoD) or Downstream Unsolicited (DU).
4. Depending on the method of label distribution (DoD, DU), the MPLS labels will be distributed
by the downstream node (DU) or the labels will be requested by upstream nodes (DoD).
5. Send unlabeled data packets from Test Port A to all advertised destinations at a set rate.
5 Spirent Communications Test Methodologies • MPLS Network Testing
6. Analyze MPLS labeled packets received at Egress LER.
7. If packet loss is observed:
a. Record traffic statistics and a Fail verdict.
b. End the test.
8. If no packet loss is observed:
a. Record traffic statistics and a Pass verdict.
9. To characterize router behavior, vary one of the following and return to Step 3. Otherwise,
end the test.
a. Number of LSPs.
b. Packet length.
c. Packet rate.
Test Parameters
a73
Number of LSPs.
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Packet length.
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Packet rate.
Test Outcome
Traffic and LDP statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 6
TM-0113
LDP Forwarding
Performance for Egress LER
a73
RFC 3036: LDP Specification
a73
RFC 2328: OSPF Version 2
Objective
This test verifies the device under test (DUT) is capable of creating LSP Tunnels as an Egress LER
using LDP to distribute labels, correctly removing the label from received labeled packets and
forwarding unlabeled IP data packets to the destination router.
Overview
An LSP is created with Test Port A as an Ingress LER and the DUT as the Egress LER. The Ingress LER
will supply MPLS labeled packets to the DUT using a label distributed by the DUT. The destination test
port will receive the unlabeled packets forwarded by the DUT and provide statistics. The system under
test (SUT) may consist of a single DUT or, optionally, a DUT with additional routers. If optional routers
are used so that the DUT and test ports are not directly connected, a route distribution method (OSPF,
IS-IS, static routes) may be necessary.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method
(OSPF, IS-IS, static routes).
2. Advertise a set number of destination routes from Test Port B.
3. Configure LDP label distribution method on the DUT and appropriate test ports as either
Downstream on Demand (DoD) or Downstream Unsolicited (DU).
4. Depending on the method of label distribution (DoD, DU), the MPLS labels will be distributed
by the downstream node (DU) or the labels will be requested by upstream nodes (DoD).
5. Send labeled data packets from the Ingress LER to all advertised destinations at a set rate.
7 Spirent Communications Test Methodologies • MPLS Network Testing
6. Analyze IP packets received at the destination Port B.
7. If packet loss is observed:
a. Record traffic statistics and a Fail verdict.
b. End the test.
8. If no packet loss is observed, record traffic statistics and a Pass verdict.
9. To characterize router behavior, vary one of the following and return to Step 3. Otherwise, end the
test.
a. Number of LSPs.
b. Packet length.
c. Packet rate.
Test Parameters
a73
Number of LSPs.
a73
Packet length.
a73
Packet rate.
Test Outcome
Traffic and LDP statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 8
TM-0107
RSVP-TE Tunnel
Establishment Stress Test
a73
RFC 2205: Resource ReSerVation Protocol
a73
RFC 3209: “RSVP-TE: Extensions to RSVP for LSP Tunnels”
Objective
This test will continually set up and tear down (flap) a number of LSPs (tunnels) for a set duration
while logging RSVP-TE statistics. Over time, this verifies the behavior of the device under test’s control
plane.
Overview
For one or many ports, define the number of LSP tunnels per port and continually flap them at a set
rate for a set duration. Record statistics periodically during the test.
Setup
Test Steps
1. Configure DUT to support MPLS RSVP-TE.
2. Continually set up and tear down (flap) LSPs at a set rate for a set period.
9 Spirent Communications Test Methodologies • MPLS Network Testing
3. Record test statistics.
a. Number of LSPs per port.
b. Number of ports.
c. Flapping interval (rate).
d. Test duration (period).
4. If RSVP-TE errors occur,
a. Record Fail verdict.
b. End the test.
5. If no RSVP-TE errors occur,
a. Record Pass verdict.
6. To characterize router behavior, vary one of the following and continue at Step 2. Otherwise, end
the test.
a. Number of flapped LSPs per port.
b. Number of ports.
c. Flapping interval.
d. Test duration.
Test Parameters
a73
Number of ports.
a73
Number of flapped LSPs per port.
a73
Flapping intervals.
a73
Duration of test.
Test Outcome
Failed tunnel establishments, Path and Resv errors and Path Tears and Resv Tears.
Spirent Communications Test Methodologies • MPLS Network Testing 10
TM-0114
RSVP-TE Forwarding
Performance for Transit LSR
a73
RFC 2205: Resource ReSerVation Protocol
a73
RFC 3209: “RSVP-TE: Extensions to RSVP for LSP Tunnels”
Objective
This test verifies the device under test (DUT), acting as a Transit LSR, can set up LSPs, correctly swap
the MPLS label and forward labeled packets. This test also determines the performance boundary of
the DUT to forward labeled packets on many LSPs.
Overview
This test will establish a number of LSPs from the Ingress LER (Test Port A) through the DUT to the
Egress LER (Test Port B). The Ingress LER will send MPLS labeled packets to each LSP and the Egress
LER will analyze each received packet. The system under test (SUT) may consist of a single DUT or,
optionally, a DUT with additional routers. If optional routers are used so the DUT and test ports are not
directly connected, a route distribution method (OSPF, IS-IS, static routes) may be necessary.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method (OSPF,
IS-IS, static routes) to advertise the address of the Egress LER to the Ingress LER.
2. Configure DUT to support MPLS RSVP-TE.
3. Set up multiple LSPs between the Ingress LER and the Egress LER.
4. From the Ingress LER, generate labeled traffic at set packet length and offered load over all LSPs.
5. Record route statistics and number of LSPs.
6. Use a binary search to adjust number of LSPs until labeled packet loss occurs at the Egress LER.
For each interation, record a Pass or Fail verdict as appropriate.
11 Spirent Communications Test Methodologies • MPLS Network Testing
7. To characterize router behavior, vary one of the following and continue at Step 3. Otherwise, end
the test.
a. Packet length.
b. Offered load.
To characterize a range of behavior, decide on a range of “traffic LSPs” and traffic definition (packet
length, load) and perform the steps above on each range.
Test Parameters
a73
Number of traffic LSPs.
a73
Packet length.
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Offered load.
Test Outcome
Traffic and RSVP-TE statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 12
TM-0115
RSVP-TE Forwarding
Performance for Ingress LER
a73
RFC 2205: Resource ReSerVation Protocol
a73
RFC 3209: “RSVP-TE: Extensions to RSVP for LSP Tunnels”
Objective
This test verifies the device under test (DUT) is capable of establishing RSVP-TE LSP tunnels as an
Ingress LER and correctly labeling and forwarding MPLS labeled packets.
Overview
LSPs are created with the DUT as the Ingress LER and Test Port B as the Egress LER. The source (Test
Port A) will supply unlabeled packets to the DUT with addresses corresponding to the LSPs connect-
ing the ingress and egress nodes. The DUT will forward MPLS labeled packets to the Egress LER,
which will capture the forwarded labeled packets for verification. The system under test (SUT) may
consist of a single DUT or, optionally, a DUT with additional routers. If optional routers are used so
that the DUT and test ports are not directly connected, a route distribution method (OSPF, IS-IS,
static routes) may be necessary.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method
(OSPF, IS-IS, static routes) to advertise the address of the Egress LER to the Ingress LER.
2. Configure DUT to support MPLS RSVP-TE and setup a static LSP with the Egress LER as the
tunnel destination.
3. Send unlabeled packets from the source test Port A to an address destination serviced by the LSP.
4. Analyze MPLS labeled packets received and Egress LER.
5. If unlabeled packets are received:
a. Record traffic statistics and a Fail verdict.
b. End the test.
13 Spirent Communications Test Methodologies • MPLS Network Testing
6. If the number of labeled packets received is equal to the number of unlabeled packets sent:
a. Record traffic statistics and a Pass verdict.
7. To characterize router behavior, vary one of the following and continue at Step 3. Otherwise, end
the test.
a. Packet length.
b. Offered load.
Test Parameters
a73
Packet length.
a73
Offered load.
Test Outcome
Traffic and RSVP-TE statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 14
TM-0116
RSVP-TE Forwarding
Performance for Egress LER
a73
RFC 2205: Resource ReSerVation Protocol
a73
RFC 3209: “RSVP-TE: Extensions to RSVP for LSP Tunnels”
Objective
This test verifies the device under test (DUT) is capable of creating RSVP LSP tunnels as an Egress
LER, and to correctly remove the MPLS label from received packets and forward unlabeled packets
to the destination router.
Overview
LSPs are created with Test Port A as an Ingress LER and the DUT as the Engress LER. The Ingress LER
will supply MPLS labeled packets to the DUT using a label allocated by the DUT. The destination
(Test Port B) will receive the unlabeled packets forwarded by the DUT and provide statistics. The
offered load and packet length may be varied to more thoroughly characterize router behavior. The
system under test (SUT) may consist of a single DUT or, optionally, a DUT with additional routers. If
optional routers are used so the DUT and test ports are not directly connected, a route distribution
method (OSPF, IS-IS, static routes) may be necessary.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method
(OSPF, IS-IS, static routes) to advertise the address of the Egress LER to the Ingress LER.
2. Send a Path message from the Ingress LER to setup an LSP with the DUT as the tunnel end
point.
3. Send MPLS labeled packets from the Ingress LER using the label that is allocated from the DUT.
The destination router of the IP packet is the test port directly attached to the DUT.
4. Analyze unlabeled packets received at destination Test Port B.
15 Spirent Communications Test Methodologies • MPLS Network Testing
5. If labeled packets are received:
a. Record traffic statistics and a Fail verdict.
b. End the test.
6. If the number of unlabeled packets received is equal to the number of labeled packets sent, record
traffic statistics and a Pass verdict.
7. To characterize router behavior, vary one of the following and return to Step 3. Otherwise, end the
test.
a. Packet length.
b. Offered load.
Test Parameters
a73
Packet length.
a73
Offered load.
Test Outcome
Traffic and RSVP-TE statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 16
TM-0117
RSVP-TE Forwarding
Performance During Tunnel
Establishment
a73
RFC 2205: Resource ReSerVation Protocol
a73
RFC 3209: “RSVP-TE: Extensions to RSVP for LSP Tunnels”
Objective
This test measures the capability of the device under test (DUT) to correctly forward MPLS labeled
packets to a stable RSVP tunnel while other tunnels are continually set up and torn down (flapped).
Overview
This test will establish two groups of LSPs: The first group will be created, left stable, and used to
forward labeled packets from the Ingress LER (Test Port A) to the Egress LER (Test Port B). Meanwhile,
the second group will be flapped. The Ingress LER will generate MPLS labeled traffic using LSPs from
the first stable group to the Egress LER. The Egress LER will analyze each received packet.
Setup
Test Steps
1. If the DUT is not directly connected to the test ports, implement a route distribution method (OSPF,
IS-IS, static routes) to advertise the address of the Egress LER to the Ingress LER.
2. Configure the DUT to support MPLS RSVP-TE.
3. Set up a number of LSPs between the Ingress LER and the Egress LER (traffic LSPs).
4. From the Ingress LER, generate labeled traffic at set packet length and offered load over all traffic
LSPs.
5. Set up multiple LSPs to be flapped (flapped LSPs).
6. Record route statistics and the number of LSPs, both traffic and flapped.
17 Spirent Communications Test Methodologies • MPLS Network Testing
7. Use a binary search to adjust number of flapped LSPs until labeled packet loss through traffic LSPs
occurs at the Egress LER. For each interation, record Pass or Fail verdict as appropriate.
8. To characterize router behavior, vary one of the following and continue at Step 4. Otherwise, end
the test.
a. Number of traffic LSPs.
b. Packet length.
c. Offered load.
Test Parameters
a73
Number of traffic LSPs.
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Number of flapped LSPs.
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Packet length.
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Offered load.
Test Outcome
Traffic and RSVP-TE statistics.
Spirent Communications Test Methodologies • MPLS Network Testing 18
TM-0118
BGP/MPLS VPN VRF
Scalability
a73
Draft-ietf-ppvpn-rfc2547bis-xx: BGP/MPLS VPNs
a73
RFC 2858: Multi-Protocol Extensions for BGP-4
a73
Draft-ramachandra-bgp-ext-communities-xx: BGP Extended Communities Attribute
a73
RFC 3107: Carrying Label Information in BGP-4
Objective
This test will determine the number of VPN routing and forwarding tables (VRFs) and routes per VRF a
provider edge (PE) router in a BGP/MPLS VPN system can support.
Overview
BGP/MPLS VPNs use Layer 3 routing information to distribute VPN connectivity information. An MPLS
backbone network provides data plane connectivity. Customer edge (CE) routers advertise their site
reachability to their directly connected provider edge (PE) routers via a routing protocol. The PE router
installs these routes into a VRF for that VPN. These VPN routes are then propagated to other PE routers
to provide this reachability information to remote VPN sites.
This test uses eBGP to distribute routes between CE and PE (DUT). Some type of sub-interfacing is
used to easily scale the test to many customer sites. Sub-interfacing will create a correspondence
between multiple logical interfaces and a single physical interface. This is typically accomplished by
assigning to each logical interface layer 2 channel identifiers, such as Ethernet VLAN IDs, Frame Relay
DLCIc or ATM VPI/VCIs. The DUT should propagate these VPN routes via MP-BGP to the PE test port
where they can be verified. LDP is used as the core MPLS protocol. Data traffic will be used to test the
validity of VPN routes.
Setup
19 Spirent Communications Test Methodologies • MPLS Network Testing
Test Steps
1. Configure a set number of sub-interfaces on each interface used in the test between the CE and PE
router (DUT).
2. Provision and associate a different VRF for each configured sub-interface.
a. Configure the VRF on DUT.
b. Configure the Route Distinguishers.
c. Configure the import and export route targets. This will help to ensure routes are installed in the
proper VRFs.
d. Configure the association between the sub-interfaces and the VRFs.
e. Configure Multi-protocol BGP on the core-facing interface of the DUT.
f. Configure OSPF and LDP on the core-facing interface of the DUT.
3. Configure eBGP between the CE-PE interfaces on each sub-interface.
4. Advertise a set number of routes from each CE to the PE.
5. Monitor the propagated routes via the MP-BGP session. This verifies that all the routes advertised
by the CEs are re-advertised properly.
6. If the propagated routes do not equal the routes advertised:
a. Record the number of VRFs and number of routes advertised and a Fail verdict.
b. End the test.
7. If the propagated routes equal the routes advertised:
a. Record the number of VRFs and number of routes advertised.
b. Use the advertised label mappings and prefixes to send data traffic from the core-facing test port
to the CE test ports.
c. Record a pass verdict for VPNs that have properly forwarded packets. Record a Fail verdict for
VPNs with packet forwarding errors.
d. End the test.
8. To characterize router behavior, vary the following and return to Step 1. Otherwise, end the test.
a. Number of physical interfaces (ports).
b. Number of routes advertised.
Test Parameters
a73
Number of physical interfaces.
a73
Number of CEs per physical interface.
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Number of routes advertised per CE.
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Offered load.
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Datagram length.
Test Outcome
Number of CEs (VRFs) created, number of routes advertised, number and list of valid VPNs, number
and list of invalid VPNs, number of physical interfaces.
Spirent Communications Test Methodologies • MPLS Network Testing 20
TM-0119
Layer 2 Frames Over
MPLS Scalability
a73
Draft-martini-I2circuit-encap-mpls-xx
a73
Draft-martini-ethernet-encap-mpls-xx
a73
Draft-martini-frame-encap-mpls-xx
a73
Draft-martini-atm-encap-mpls-xx
Objective
The goal is to test the functional behavior of a PE device when provisioning Martini virtual circuits and
forwarding traffic over those established virtual circuits.
This test allows the operator to verify the proper control plane signaling and data plane forwarding of
Martini-encapsulated traffic by checking the LDP extensions for Martini signaling, as well as the
complex encapsulation and de-encapsulation of Martini traffic.
Overview
Two test ports are required for determining the Martini virtual circuit (VC) capacity of a system under
test (SUT). All test ports will be connected to the SUT. One test port will be connected to the
customer-facing side of the SUT, and one port will be connected to the core-facing side.
A user-specified number and type of VC is established via LDP on the core-facing port of the SUT.
These circuits are mapped by the SUT to and from the customer-facing port through the core-facing
tunnels. The label and virtual circuit information exchanged with the SUT’s core-facing port is gathered
for use in the generation and analysis of data traffic.
Layer 2 traffic is configured and offered to the customer-facing side of the SUT to be analyzed as
Martini-encapsulated frames on the core-facing port of the SUT. Conversely, Martini-encapsulated
traffic is configured and offered to the core-facing side of the SUT to be analyzed as Layer 2 traffic on
the customer-facing side.
The number of valid VCs can be evaluated. Encapsulation/de-encapsulation problems can be
reported.
21 Spirent Communications Test Methodologies • MPLS Network Testing
Setup
The test configuration and setup diagram, showing details such as test ports and traffic distribution,
helps explain the test procedure.
The virtual circuit tunnels occur between the DUT (PE) and the right side test port (PE). The test creates
virtual circuits to map the virtual customer endpoints on the left, with the virtual customer endpoints
on the right.
Test Steps
1. Physical connectivity − This test requires at least two test ports. Connect at least one port to the
“customer-facing” side of the DUT and one port to the “core-facing” side ofthe DUT.
2. Virtual circuit provisioning − Configure the DUT for the number of VCs needed for the test:
a. Configure the DUT for LDP and OSPF on the core-facing interface.
b. Map a Layer 2 circuit from a customer side interface to a VC ID and the PE test port IP address.
The Layer 2 circuit will be identified by a VLAN ID, Frame Relay DLCI or ATM VPI/VCI.
c. Repeat Step 2b for all VCs needed.
3. Core facing test port configuration (PE test port):
a. Configure OSPF to establish adjacency with DUT.
b. Configure LDP to establish session with DUT.
c. Advertise interface address through LDP.
d. Configure VC FEC label mappings using Downstream Unsolicited (DU) mode for the VCs
configured in Step 2. The same VC IDs and traffic type must be used. This is for traffic flowing in
the opposite direction.
4. Traffic configuration.
a. Configure the customer-facing test ports (CE test ports) for generation
i. Define test streams for the Layer 2 circuits defined in Step 2b.
ii. Set the offered load and packet length parameters to the desired settings.
Spirent Communications Test Methodologies • MPLS Network Testing 22
b. Configure the customer-facing test ports for analysis – set the analyzer filter to the appropriate
Layer 2 ID (VLAN ID, DLCI or VPI/VCI).
c. Configure the core-facing test ports for generation.
i. Define test streams by mapping the inner label values assigned by the DUT to the
appropriate Martini encapsulation type and Layer 2 ID for each VC. Add the outer label for
the core tunnel if applicable.
ii. Set the offered load and packet length parameters to the desired settings.
d. Configure the core-facing test ports for analysis set the analyzer filter to filter on the inner label
value and appropriate Layer 2 ID.
5. Run test.
Test Parameters
a73
Number of configured VCs.
a73
Layer 2 ID and VC ID for each configured VC.
a73
Offered load, packet length and other traffic configuration parameters.
Test Outcome
1. VC statistics.
a. Number of VCs successfully established.
b. Encapsulation/de-encapsulation errors.
i. Packets switched with wrong Layer 2 ID on customer-facing interfaces.
ii. Packets switched with wrong inner label on core-facing interfaces.
c. Rx packet rate, packet loss, packet sequence errors, packet count.
23 Spirent Communications Test Methodologies • MPLS Network Testing
Spirent Communications Test Methodologies • MPLS Network Testing 24
Appendix
Acronyms
AS – Autonomous System
ATM – Asynchronous Transfer Mode
BGP – Border Gateway Protocol
CE – Customer Edge
DLCI – Data Link Connection Identifier
DoD – Downstream on Demand
DU – Downstream Unsolicited
DUT – Device Under Test
EBGP – Exterior Border Gateway Protocol
FEC – Forwarding Equivalence Class
FIB – Forwarding Information Base
ID – Identifier
IGP – Interior Gateway Protocol
IP – Internet Protocol
IPv4 – Internet Protocol Version 4
IPv6 – Internet Protocol Version 6
IS-IS – Intermediate System to Intermediate System
LDP – Label Distribution Protocol
LER – Label Edge Router
LSA – Link State Advertisements
LSP – Label Switched Path
MP-BGP – Multi-Protocol Border Gateway Protocol
MPLS – Multi-Protocol Label Switching
OSPF – Open Shortest Path First
PE – Provider Edge
RFC – Request For Comment
RIB – Routing Information Base
RSVP – Resource Reservation Protocol
RSVP-TE – Resource Reservation Protocol with Traffic Engineering
Rx – Receive
SUT – System Under Test
Tx – Transmit
VC – Virtual Circuit
VLAN – Virtual LAN
VPN – Virtual Private Network
VRF – VPN Routing and Forwarding
25 Spirent Communications Test Methodologies • MPLS Network Testing
Glossary
A
Adjacency A relationship that is established between two routers in the process of exchanging
routing protocol messages (example: BGP or OSPF adjacency).
AS (Autonomous System) A part of a network under a single administrative domain. Usually running
a single internal routing protocol.
B
BGP (Border Gateway Protocol) The exterior gateway protocol used for distributing routes over the
Internet. Currently, Version 4 (BGP-4) is used.
BGP Speaker A router that runs the BGP-4 routing protocol. When two BGP speakers are forming
an adjacency, they are called “BGP peers” or “neighbors.”
Binding The process of associating a label with a Forwarding Equivalence Class (FEC).
C
CE Device (Customer Edge Device) Router or switch in the customer’s network that is connected to
a service provider’s provider edge (PE) router and participates in a Layer 2 or Layer 3 VPNs.
Control Binding Using Control Messages (such as the Label Distribution Protocol) or specific
predetermined commands and parameters to bind a label to an FEC. This is a static form of binding.
Customer Edge Device See CE device.
CIDR (Classless Inter-Domain Routing) IP routing which uses the subnet masks to determine the size
of each individual subnet. Supports variable subnet lengths. Obsoletes the concept of “Class A, B, C”
networks.
Client Peer In BGP route reflection, a member of a cluster that is not the route reflector. See also
nonclient peer.
Cluster In BGP, a set of routers grouped together. A cluster consists of one system that acts as a
route reflector, along with any number of client peers. The client peers receive their route informa-
tion only from the route reflector system. Routers in a cluster do not need to be fully meshed.
CR-LDP (Constraint-Based Routing Label Distribution Protocol) Extensions of the Label Distribution
Protocol (LDP) to support traffic engineering.
CPE (Customer Premises Equipment) Telephones, routers or other equipment located at a customer
site.
Constrained Path In traffic engineering, a path determined using RSVP-TE or CR-LDP signaling and
constrained using CSPF. The ERO carried in the packets contains the constrained path information.
CSPF (Constrained Shortest Path First) A Shortest Path First (SPF) IGP algorithm that has been mod-
ified to take into account specific restrictions when calculating the shortest path across the network.
D
Data-Driven Binding Dynamically binding a label to an FEC based upon the data stream.
DLCI (Data Link Circuit Identifier) Frame Relay circuit identifiers.
DoD (Downstream on Demand) A method for assigning labels via a label distribution protocol. The
ingress router requests a label from the remote end.
Spirent Communications Test Methodologies • MPLS Network Testing 26
DU (Downstream Unsolicited) A method for assigning labels via the Label Distribution Protocol. The
egress router assigns labels without being requested to do so from the ingress router.
E
EBGP External BGP Protocol that governs the relationship between BGP speakers belonging to
different Autonomous Systems.
EGP (Exterior Gateway Protocol) Any routing protocol used for distributing routes between
autonomous systems. BGP-4 is now the most commonly used Exterior Gateway Protocol.
Egress The location at which a datagram exits the MPLS network.
ER (Explicit Route) A route specified at the point of origination. Does not require routing decisions
at each hop of the network.
ERO (Explicit Route Object) Extension to RSVP or LDP that allows an RSVP-TE PATH message or
CR-LDP Label Request to traverse an explicit sequence of routers that is independent of conven-
tional shortest-path IP routing.
F
Fast Reroute Mechanism for effecting local repair by automatically rerouting traffic from an LSP if
a node or link in the LSP fails, thus reducing the loss of packets traveling over the LSP.
FEC (Forwarding Equivalence Class) A group of IP packets forwarded in the same manner – that is,
over the same path, with the same priority and the same label.
FIB Forwarding Information Base. A database belonging to a particular router that contains all the
necessary information to forward packets from this router to another. The routes installed in the FIB
are the best existing routes available at that moment and are used to direct incoming packets to
their destination.
I
IBGP Internal BGP. Protocol that governs the relationship between BGP speakers belonging to the
same Autonomous System.
IGP (Interior Gateway Protocol) A routing protocol for distributing routes within a single Autonomous
System. RIP, OSPF and IS-IS are the most commonly used IGPs.
Ingress The point at which a datagram enters the MPLS network.
IP Prefix A number that uniquely identifies a network or set of networks. The IP prefix of a network
consists of the most significant bits that are common to the IP addresses of all nodes belonging to
that network.
IPSec (IP Security) A security transmission protocol for protecting and authenticating IP packets
between clients.
L
L2TP (Layer 2 Tunneling Protocol) A protocol for creating a tunneling session across a WAN.
Label A short fixed-length identifier associated with a Forwarding Equivalence Class. (In MPLS, 20-bit.
unsigned integer in the range 0 through 1048575 used to identify a packet traveling along an LSP.)
Label Merging The replacement of multiple incoming labels for an FEC with a single outgoing label.
Label Stacking Adding multiple MPLS Labels to a single datagram. This can be used when multiple
MPLS networks are traversed and is also used for MPLS VPNs and fast reroute.
Label Swapping Using the incoming label to determine the outgoing label, encapsulation and port.
Then replacing the incoming label with the outgoing label.
LDP (Label Distribution Protocol) A protocol used for distributing MPLS labels within MPLS. There
are multiple types of label distribution protocols of which “LDP” is only one possible choice.
LDP Peers Two routers that exchange information with each other via the Label Distribution Protocol.
27 Spirent Communications Test Methodologies • MPLS Network Testing
LER (Label Edge Router) A router at the ingress and/or egress of the MPLS network. This router
assigns and/or removes the datagram’s label.
Loose In the context of traffic engineering, a path that can use any route or any number of other
intermediate (transit) points to reach the next address in the path. (Definition from RFC 791,
modified to fit LSPs.)
LSA Link state advertisement. Unit of information that is advertised by an OSPF router to the other
routers in the network. The Link State Advertisement reflects the state of the router interfaces and
adjacencies.
LSP (Label Switched Path) A data-forwarding path through one or more LSRs determined and
based upon the labels attached to each data packet.
LSP Tunnel A traffic engineering LSP capable of carrying multiple data flows.
LSR (Label Switch Router) An MPLS-capable router.
M
Martini A method of transporting Layer 2 frames over an MPLS or IP network. Defined in
draft-martini-l2circuit-encap-mpls-xx.
MPBGP (Multi-Protocol BGP) An extension to BGP that allows advertisement of IPv6, multicast,
VPN- IPv4 and other non-IPv4 topologies within and between BGP autonomous systems.
MPLS (Multi-Protocol Label Switching) A set of protocols for the Internet, which facilitate packet
forwarding based on simple labels for connection-oriented capabilities.
MPLS Domain A contiguous set of nodes that operate MPLS routing and forwarding and are found
in one Routing or Administrative Domain.
MTU (Maximum Transfer Unit) Limit on segment size for a network.
O
OSPF (Open Shortest Path First) A commonly used interior gateway protocol.
Overlay The process of running MPLS (Label Switching) over an ATM (cell switching) network.
P
Path Attribute Information associated with a particular route. It describes the characteristics of the
route and is used to determine the best path to a destination. The Path Attributes are sent as part of
BGP protocol messages.
Penultimate LSR The LSR in a traffic flow immediately prior to the egress router. This LSR can also
remove the Label from the packet prior to forwarding the datagram to the egress router. This is used
to simplify the egress router’s job.
PE Router (Provider Edge Router) A router in the service provider’s network connected to a customer
edge (CE) device and that participates in a Virtual Private Network (VPN).
Provider Router (or P Router) Router in the service provider’s network that does not attach to a
customer edge (CE) device.
PPVPN (Provider Provisioned Virtual Private Network) A virtual private network managed by a service
provider compared with a client-based VPN that is managed by an enterprise or end user.
R
RIB Routing Information Base. A database or collection of databases belonging to a particular router
that contains the image of the network topology. The information in a router’s RIB is assembled from
incoming route advertisements, and it is used to calculate the best paths to all known destinations
for installment in the FIB.
RIP (Routing Information Protocol) Another commonly used interior gateway protocol. Typically used
for smaller or simpler networks, while OSPF supports large complex infrastructures.
Spirent Communications Test Methodologies • MPLS Network Testing 28
Route Distinguisher Identifier attached to a routing update that distinguishes which VPN it belongs
to. Each VPN must have a unique distinguisher associated with it. Each route distinguisher is a
6-byte value.
Route Flapping The repeated advertisement and withdrawal of a route or set of routes due to
network instability.
RSVP (Resource Reservation Protocol) A signaling protocol that reserves resources throughout an
IP network. Supports IP QoS.
RSVP-TE (Resource Reservation Protocol with Traffic Engineering) One of the two commonly used
signaling protocols for the establishment, maintenance and removal of LSPs.
S
S-Bit (Bottom of Stack Bit) A single bit in the MPLS header that indicates the last label in the packet.
Shim Another term for an MPLS label inserted between the layer-2 and layer-3 headers of a packet.
SLA (Service Level Agreement) An agreement (usually a contract) between a service provider and a
customer. Guarantees a certain quantitative and/or qualitative level of service.
Static Path In the context of traffic engineering, a static route that requires hop-by-hop manual
configuration. No signaling is used to create or maintain the path. Also called a static LSP.
Strict In the context of traffic engineering, a route that must go directly to the next address in the
path. (Definition from RFC 791, modified to fit LSPs.)
T
TLV (Type-Length-Value) An encoding method for protocol messages.
Traffic Engineering Process of selecting the paths chosen by data traffic to balance the traffic load
on the various links, routers, and switches in the network. (Definition from
http://www.ietf.org/internet-drafts/draft-ietf-mpls-framework-04.txt.) See also MPLS.
Transit Router In MPLS, any intermediate router in the LSP between the ingress router and the
egress router.
Tunnel Private, secure path through an otherwise public network.
V
VLAN Virtual LAN (IEEE 802.1Q). A network whose elements behave as if they are connected to
the same physical LAN even though they might be located on separate physical networks.
VoMPLS (Voice over MPLS) A method for carrying voice traffic over an MPLS network.
VPI/VCI (Virtual Path Identifier/Virtual Channel Identifier) ATM channel identifiers.
VPN (Virtual Private Network) A private network created by utilizing shared resources within a
public network.
VRF (VPN Routing and Forwarding) The forwarding table contained within a PE router for Layer 3
VPN support.
29 Spirent Communications Test Methodologies • MPLS Network Testing
Spirent Communications Test Methodologies • MPLS Network Testing 30
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