Emerging MPLS OAM
mechanisms

Answering the interoperabilityand scalability question
Data Networks Operation
John Nakulski
Product ManagerOctober 2006

Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 1

AgendaIntroduction – The Need for MPLS OAM
Comparison: OAM in Legacy & MPLS Networks
Emerging MPLS OAM Mechanisms• Review• Development & Deployment Challenges

New Test Methods to help you ensure MPLS Scalability andHigh Availability

Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 21

Introduction – The Need for MPLS OAMMPLS has emerged as thetechnology of choice for thedeployment of next generation
converged networks
MPLS-specific operations,administration and maintenance(OAM) mechanisms are being
developed to help Carriers supportand maintain their MPLS networks

Performance
Measurement
MPLS trace

What is OAM?

BFD

A collection of mechanisms &processes used to monitor thehealth of a network and todiagnose problems that mightoccur within the network

Source: “Service Provider Plans for IP, MPLS, and ATM: North America,
Europe, and Asia Pacific 2005” – Infonetics Research, December 2005
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 3Comparison of Legacy and MPLS OAMSONET & SDH

FailureDetection
andDiagnostics• Alarms & event
indications (LOS,OOF, LOF, LOP,AIS, RDI, LOM…)• Loopback• Path & Section
Trace• APS (50 ms)

Recovery

Performance
Monitoring• LCAS for virtual
concatenation• BIP-N parity error• Path statusATM• Alarm Indication
Signal AIS• Remote DefectIndication RDI

Carrier
Ethernet

MPLS• Bidirectional
Forwarding
Detection (BFD)• 802.3 Clause 57(was 802.3ah) LinkMonitoring, Remote
Failure Indication,
Remote Loopback• F4 (VP) & F5(VC) end-to-end
and segment
Continuity Check& Loopback Test

• LSP Ping

• ATM Protection
Switching (I.630)• Fast Reroute• EAPS (RFC3619),
EAPSv2, G.8031• Make-beforebreak• LACP, RPR• LSP Ping

• 802.3 Clause 57
Link performancemonitoring• IMA• Performance
Monitoring (I.610)(round-trip delay,inter-arrival jitter)• VCCV• 802.1ag CFM for
end-end services• LSR Self-Test• ITU Y.1730, Y.1731• MEF Service needs• STP, RSTP, MSTPEmerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

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MPLS OAM Data Plane Mechanisms
Data plane & LSP tunnel connectivity:• LSP Ping – Ping and Traceroute mechanism customized for
operation within MPLS LSP tunnels• Virtual Circuit Connectivity Verification (VCCV) – Used forverifying the connectivity status of MPLS pseudo wires

Link & path connectivity:• Bidirectional Forwarding Detection (BFD) – Genericlightweight hello protocol use to detect link & path failures
between adjacent nodes

Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 5

LSP Ping Overview
IngressLSR

42 LSP Ping

65 LSP Ping

42LSP Ping

65

LSP Ping Reply• LSP Ping provides a mechanism fordetecting data plane failures in MPLS
LSP tunnels• It can be used to monitor the status ofactive LSP tunnels by performing
connectivity checks

LSP• LSP Ping Echo packets areencapsulated with the same label stackas used by the LSP. Therefore the Echo
packet travels along the exact same pathas the LSP• LSP Ping can operate in two modes:– Ping mode is a simple end-to-endloopback– Traceroute incrementally verifies eachnode along the LSP path

• It can diagnose and isolate LSP faults
by performing hop-by-hop path tracing• LSP Ping is a MPLS-specific variationof traditional IP/ICMP Ping

EgressLSR• LSP Ping is specified in IETF RFC 4379
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 63

Bidirectional Forwarding Detection (BFD) Overview
BFD ControlPacket

BFD ControlPacket• Simple, lightweight “hello” protocol used • The participating nodes negotiate how
to detect path failures between nodes
quickly they can send & receive BFD
control packets. This negotiated timer• Each node periodically transmits BFD
will determine how quickly a path failure
Control Packets across a specific pathcan be detected• If a node stops receiving BFD packets• A BFD path can be any of the following:
then some component of the path is• Direct physical link
assumed to have failed• Multi-hop routed path
• Virtual circuit• MPLS LSP tunnel• IETF BFD working group• draft-ietf-bfd-base-05.txt• draft-ietf-bfd-mpls-03.txt

Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 7

Other MPLS OAM Mechanisms
ITU-T Study Group 13• Y.1710 – Specifies requirements for MPLS OAM• Y.1711 & Y.1713 – Equivalent to BFD• Y.17fw – Specifies and leverages IETF VCCV and LSP-Ping for LSP
tunnel connectivity verification• Y.1720 – “Protection switching for MPLS networks" (Nov 2002).

IETF• LSR Self-Test – A mechanism to allow a router to test its own label
forwarding engine by using an upstream and downstream LSR neighbor

Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 84

MPLS OAM Challenges
MPLS OAM is new but unproven…
need to test latest devices• Interoperability: Multiple vendor devices• Scalability: Stability & performance in large
carrier networks, with thousands of tunnels• “Ships in the night”: No interference withother control plane mechanisms

VPNs
Routing
LSP Ping
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 9Testing LSP Ping (1)Validate router LSP Ping implementations
Functionality

Scalability• Ping response accuracy• Trace response data

• Stability under load (high ping rate,large meshes of active tunnels)• Measure performance limits

Negative test (abnormal conditions)• Inactive and non-existent LSPs
• Incorrectly formed packets• Unexpected messages (echo reply)

Impact on data plane performance• Generate LSP traffic; measure packet
loss, latency during a LSP Ping “storm”

Impact on control plane performance• Stress routing, signaling, OAM andtraffic capabilities simultaneously

Test traffic

LSP Ping

LSP Ping
performance
Router CPUmax load

Flap LSPs using
LDP or RSVP
Flap OSPF or
IS-IS routes

Route and LSP flap rate
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

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Testing LSP Ping (2)Monitor LSPs and diagnose faults in testbeds and live networks
Switching and SignallingHigh Availability• Look for LER & LSR faults – during LSP
flapping, check LSP setup and teardown• Gauge MPLS FRR / LSP Switchover time,Make-Before-Break and tunnel pre-emption• Using RSVP & LDP, measure LSP setup
time and characterize MPLS scalability

IPv6 Transition• Test IPV6 BGP/MPLS tunnelling operation

Pseudo-wire and VPN Services• Confirm connectivity, check stability and quantify
scalability during services testing of P, PE and CE routers

LSP Ping Test Results
LSP Ping verifies
L3 VPN services
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 11Testing BFD and Fast ReRoute
Verify LSP reroute after BFD goes down
Test that BFD fault detection triggers MPLS Fast ReRoute,and verify service restoration

Test scenario
1. Emulate MPLS Routers with BFD; setup multiple tunnels and backup tunnels; use LSP
Ping between Test Port A and Test Port B to verify tunnel connectivity
2. Initiate BFD down at Port B, forcing reroute to backup tunnels at Port C
3. Use LSP Ping/Trace to verify connectivity and path (for each tunnel) at Port C, measure
fast reroute time, and measure impact of reroute on ping echo delay
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 126High Availability
MPLS OAM complements existing HA technologies

LSP Ping is a proactive mechanism that complements other
HA technologies, to build confidence in MPLS networks• Fast ReRoute
BFD

LSP Ping• Make Before BreakTest Port• Tunnel pre-emption

Fast ReRoute

Test Port• RSVP Graceful Restart

RSVP, OSPF, IS-IS andBGP Graceful Restart• Bidirectional Forwarding Detection• IP-layer and hardware technologies

Test Port– BGP/IS-IS/OSPF Graceful Restart– Non-stop routing

These must be tested together
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 13Creating and Implementing MPLS Test Plans
What to look for in a test solution?
• Comprehensive coverage of MPLS,VPNs, routing, HA, and Multicast• MPLS OAM protocol emulation– Fully integrated software application• High protocol performance to verify
device scalability and stability– MPLS: 1,800 LDP sessions or
400,000 LSP tunnels per port
– Routing: 4,000 BGP sessions/port

VPLS over MPLS Scalability Test

• A complementary guide-book on test
methodologies to save time during
test plan creation• Automated tests to save time duringtest plan implementation
Fast ReRoute / LSP Switchover Time Test
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

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Summary
OAM mechanisms will make MPLS truly
carrier-class and ready for real-time services
This introduces new challenges• Interoperability

VPNs• Scalability

Routing• Interference with other control-plane mechanisms

LSP Ping

Testing MPLS OAM and other HAmechanisms together will give you
confidence in your MPLS network devices,and let you sleep easy!
Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

Page 15

Questions?

Emerging MPLS OAM mechanisms
Answering the interoperability & scalability question
October, 2006

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