Achieving Reliability
in Converged MPLS
NetworksMartin Lai
MPLS Japan
November 2005

Page 1

Data Networks Division
Copyright, Agilent Technologies 2005
平成17年11月6日

Agenda• Services Are Converging• The Service Disruption Problem• The High Availability Solution• Validating High Availability Mechanisms

Page 2Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Services Are Converging
Key Drivers• Real time triple play services (IPTV, VoIP) will be delivered overa converged IP/MPLS core. These services require stringent
QoS mechanisms to guarantee the user experience• Rationalisation of services onto a single IP/MPLS infrastructurewith reduce capital (CAPEX) and operational (OPEX) expenses• Emerging wireless services will also have an impact on the core
IP/MPLS network.

A converged IP/MPLS infrastructure carrying multiple diverse
services has to be reliable

Page 3

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Services Are Converging
Carrier/Service Provider Business Challenges
77%

Revenue growth54%

Profitability

50%

Business Challenges

Competition
Reducing operationalexpenditures

42%

Customer retention

42%

Creating new services

38%Entry into new markets

38%

Reliability is a key
enabler for meetingthese businesschallenges

35%

Regulatory environment
Reducing capital
expenditures

31%
19%

Reducing debt
Relationship with incumbent
service provider

12%

Mergers and acquisitions

8%

0%

20%

40%

60%

80%

Percent of Respondents Rating 6 or 7
Service Provider Plans for IP, MPLS, and ATM: North
America & Europe 2004. Infonetics, Dec 2004

Page 4

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Services Are Converging
Network High Availability Use
88%
96%

Deploy dual routers ateach core node88%

Non-stop routing/nodal
high availability

50%
85%
85%

Technologies

Overprovision bandwidth

50%
81%

MPLS fast re-route

69%
62%
65%

SONET APS/SDH MSP

62%
54%

Virtual Router
Redundancy Protocol

62%

Fast convergence/sub
50ms link recovery

42%
62%

Hitless software
upgrade/patching

31%
42%
35%

Link aggregation restoration0%Service Provider Plans for IP, MPLS, and ATM: North
America & Europe 2004. Infonetics, Dec 2004

Page 5

A mix of High
Availability
techniques areneeded to build
reliability into thenetwork

85%

Graceful restart/non-stop forwarding
using routing protocol extensions25%
50%
75%
Percent of Respondents

2005
2004
100%

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

The Service Disruption Problem
Reliability in Traditional Networks• Routing protocol instabilities would often disrupt packet
forwarding on early Router implementations (e.g. lost or delayedpackets)• Traditional IP & MPLS route convergence algorithms take toolong to recover from network topology changes• Service disruption times are in the order of minutes andperformance degradation is likely to be significant

Reducing service disruption is a top priority as it can have anegative impact on revenue and customer satisfaction

Page 6

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

The High Availability Solution
Reliability Technology Evolution
VoIP, IPTV, VoD
Services &Applications

VPNs, SANs
Web Browsing, E-Mail, FTP, Chat
Minutes

Tolerable
Service
Disruption

Minute/Seconds
Second/Sub-second
Five x 9’s

Reliability
TargetBest Effort

Underlying
TechnologyPage 7• Reconvergencealgorithms• Redundant control • Graceful Restart
planes• Non-StopForwarding• Partitioned s/w
architecture• Non-Stop Routing• MPLS Fast RerouteAchieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

The High Availability Solution
Mechanisms, Principles & Impact
HA Mechanism

Principle of Operation

Network Impact

Redundant Control
Plane

Hardware protection - Two Routing sessions still restart.
independent control planes
Forwarding plane exposedwith mirrored routing tables. and service delivery disrupted.

Graceful Restart (GR)Forwarding plane preserved Service delivery continues;
as control plane recovers routing protocol recovery timeusing neighbours as helpers and network ripple minimised.

MPLS Fast ReroutePre-established tunnel cutover. Works inconjunction with GR andNSF

Minimises forwarding plane
impact in the event of MPLS
link or node failure.

Non Stop Routing

Routing updates continue
between RIB and FIB in theevent of an outage

Network operation continues
as normal.

Achieving 99.999% reliability requires a mix of HA mechanisms
Page 8

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
The Need to Test
• There will be multiple HA mechanisms utilised. The complex
interaction between the individual mechanisms needs to beunderstood and tested.
• Multi-protocol environments are a necessity but unfortunately it
also increases network complexity. Network nodes will be running
multiple control and routing protocols (e.g. BGP, OSPF/ISIS, RSVP,LDP)• Edge nodes (PE) are considered amongst the highest risk devices
as these typically have a large number of peering relationships• The network is only as reliable as its weakest link

Quantifying the robustness of HA mechanisms in a realistic test
environment is essential to minimize service disruption
Page 9Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
Test Method 1 – Scaled MPLS Fast Reroute
Simulated Failure Modes:
Laser Off (Line and Node Protection)
Bring down PPP (Line and Node Protection)
Withdraw LSA (Node Protection Only)
SONET Alarm (Line and Node Protection)

Establish multiple primaryand backup LSP tunnels

SourceTest Ports

Destination
Test Ports

Simulate common topology
using OSPF or IS-IS

Primary LSP

Backup LSP

Simulated OSPF or IS-IS Topology

Generate MPLS packets
on each tunnel

Sever primary link toforce failover

Measure packet loss and time taken
to remove traffic to backup LSP

1) Measure duration of switchover to backup MPLS LSP
2) Measure packet loss, latency and jitter

Page 10

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
MPLS Fast Reroute Measurements

Measure ofswitching
duration for asingle LSP whichindicates service
disruption time

Transmitted
LSP Load
Rx Packet
Load

RX PKTS/SEC
AT TP3

RXPKTS/SEC
AT TP2TimeArearepresents
packet loss

The right measurements are critical to verify that HA
mechanisms are operating correctly
Page 11

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
MPLS Fast Reroute Measurements

Max LSPs
supported

Time for LSP
Switchover

After multiple tests, plot agraph of switchover time
versus # LSPs to measurescalability limits

FRR TimeLimit# LSPs

The right measurements are critical to verify that HA
mechanisms are operating correctly
Page 12

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
Test Method 2 – Multi-protocol Graceful Restart
Advertise network routes
using multiple protocols
behind ports TP2 & TP3

Withdraw some routes from
TP2 for a period at least as
long as max GR time

4
Generate IP Packets
to each routePreferred
Path5

Non-PreferredPathEstablishbaseline
performance
to TP2Force restart orsoftware upgrade1)2)3)4)Page 13

Verify continuity of forwarding for the duration of graceful restart
Verify that restart duration is within the specified time interval
Confirm database re-sync after removal of routes marked as ‘stale’ during restart
Verify impact of restart on other protocol functions; software architecture demarcation
Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
Graceful Restart Measurements
RX Pkts/Secat TP3
Expected Rx
pkts/sec

Measuring
Graceful RestartDuration
TimeThe right measurements are critical to verify that HA
mechanisms are operating correctly
Page 14

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
Graceful Restart Measurements
Time to GR
complete

Quantify
networkscalability andperformance
GR TimeLimit# Routes or# Peers

The right measurements are critical to verify that HAmechanisms are operating correctly
Page 15

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Validating High Availability Mechanisms
Test Capabilities

Page 16

Test Capability

Primary Benefit

Comprehensive HA
protocol coverage

Allows all the key HA mechanisms to be tested
individually or concurrently

Concurrent multi-protocol
emulation

Provide a more realistic environment for
improved test accuracyAbility to scale the test

Verify that the HA mechanisms continue tooperate correctly in large & complex network
topologies

Real Time Measurements& Graphs

Provide real time instant feedback on theperformance of the HA mechanisms under test
– reduce the “time-to-insight” factor

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日

Summary

Page 17Trends

A converged IP/MPLS infrastructure will carry multiple services
and applications – reliability will be a key requirement

Risks

Service disruption has a negative impact on revenue andcustomer satisfaction

Solutions

Designing IP/MPLS networks using High Availability
mechanisms and techniques is critical for ensuring reliabilityValidation

Network conditions change over time. HA mechanisms must
be continually validated to ensure that they remain effectiveTools

HA test tools can be used to verify that HA mechanisms are
performing correctly in highly-scaled multi-protocol networks

Achieving Reliability in MPLS Networks
Agilent Technologies, Copyright 2005
平成17年11月6日