How to alleviate
the Diff-Serv TE
Network Design Complexity ?
Didier Bousser
dbousser@wandl.com
WANDL System Engineering
Farid Azarani
farid.azarani@bell.ca
Bell Canada Core IP Engineering

1About Bell Canada Bell Canada is the leader inTelecom in Canada for IP
Services: Tier 1- Internet Service
Provider, Voice over IP, MPLSVPN (RFC 2547), Ethernet(RPR), Frame & ATM Services.

2

About WANDL Head office in USA (NJ) with customer support offices

in Singapore, UK, Italy and Belgium 19 year expertise in Network Design/Planning

Automation/OSS.
 Technical Partnerships with Cisco, Juniper, Tellabs,Alcatel, Nortel, Lucent,…
 Customers
 Telco, PTTs
 ISPs, Service Providers

3

Quick reminder about DiffServ-TE
 DiffServ-TE adds the class of service dimension to “regular”

MPLS-TE.
 RSVP Resources in the network are specified on a class basis
 Call Admission Control is performed per class

FeatureResource reservation

DiffServ

Queuing reservation (data plane)

point to point

MPLS-TERSVP bandwidth (control plane)end to end

DiffServ-TE

RSVP bandwidth per IP class(control plane)end to end

4ScopeCisco DiffServ-TE IOS implementation
 Two types of tunnels can be defined: “Data tunnels” are constrained by the RSVP Global Pool bandwidth “Voice tunnels” ONLY are constrained by the RSVP Sub Pool bandwidth Cisco current DiffServ-TE is based on Russian Doll Model Sample configurationinterface POS5/1
ip rsvp bandwidth 150000 150000 sub-pool 45000!

global-poolinterface Tunnel2000
tunnel mpls traffic-eng bandwidth sub-pool 50000!

sub-poolinterface Tunnel3000
tunnel mpls traffic-eng bandwidth 50000

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Juniper DiffServ-TE implementation
 Two options for Juniper DiffServ TE: Single class LSP
 Multi-class LSP
 Two bandwidth models to perform Call Admission Control: Russian Doll Model (RDM) Maximum Allocation Model (MAM)

Bandwidth sharing

Single class LSP

Number of bandwidth
constraints
1( L-LSP)
Multi-class LSP

Up to 4

RDM or MAM(E-LSP)

6

RDM or MAM

Juniper DiffServ TE configuration
mpls stanzadiffserv-te {class of service stanzascheduler-maps {simple-map {bandwidth-model mam;forwarding-class AF scheduler fair;}

forwarding-class BE scheduler fair;label-switched-path l-lsp {to 145.255.45.48;

forwarding-class NC scheduler fair;bandwidth ct1 10m;

forwarding-class EF scheduler fair;}}label-switched-path single-class-lsp {}to 145.255.45.48;

schedulers {bandwidth ct2 5m;

fair {
transmit-rate percent 25;}

buffer-size percent 25;}}

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Diff-Serv TE complexity
 DiffServ-TE is a very convenient mechanism forenabling bandwidth guarantees similar to ATM ClassOf Service in multimedia networks.
 Yet DiffServ-TE is complex to manage:
 Russian Doll Model is not so intuitive when available
bandwidth is to be calculated per class Tunnels/LSP for the “smallest doll” need to be assigned a highpriority/preemption to get some shares of the bandwidth And because of MPLS-TE intrinsic complexity…

8MPLS-TE design: many options…
Main purpose“Real” Traffic
Engineering

Network Protection
only

Tunneldeployment

Full mesh

One-Hop Tunnel

Link colors

All links

Limited: e.g. only
“transcontinental” links

Primary Tunnel
Bandwidth

0 BW

auto-bandwidth

User-defined

Backup Tunnel
Bandwidth

0 BW% of interface BW% of Primary
Tunnel BW

Inter-area TE

RequiredVia verbatim path
optionNo

Multicast TE

Required

Only for major sourcesof trafficNo.

9Deliver Traffic
MatrixLimited/regionalNo

Recommendations for DiffServ-TE roll out DiffServ-TE is usually deployed

on top of a multi-layer network.
 Multi-layer Design requires a goodknowledge of the interaction
between the various layers.
 Design of Layer “N” requires that
Layer “N-1” is properly engineered

DiffServ-TE

MPLS-TE/FRR

OSPF

DiffServ

 Automate the engineering tasks:
 audit/inventory/analysis of Baseline
 Network Design Network Provisioning

10SONETReal life case study

How to effectively manage the deployment
and the organic growth ofToll Voice Trunks in a Multi-Service MPLS-IP
Infrastructure

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Bell Canada IP Network & Services
 Halifax (Canada) to Palo Alto (USA) ~8000 KM
 Internet Peering & Transit
 MPLS-TE/FRR Tunnels (WAN Consolidation)
 VPN IPSec Service
 VPN 2547 Service
 DSL PPOE Internet Retail & Wholesale Service
 Business Internet Retail & Wholesale Service
 FoMPLS Service
 Inter-AS VPN Service for World Wide Private VPN Connectivity

12Bell Canada MPLS-IP Core NetworkFeatures
MPLS VPNInter AS VPN

VoIP

DiffServ-TE

Pseudo WireBGP and MP-BGP

QoS

MPLS-TE/Fast Reroute

MPLS LDP

Existingfeatures

2006features
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Bell Canada IP Network POP Architecture

DSL Aggregation
72XX,JNPR-E Series

Tier 2 City

Tier 1 CityLER Routers
75XX, 12XXXLSR Routers
12XXX
OC48
OC12
Core PoP

Access PoP

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Bell Canada Fast Reroute Deployment
Primary TE tunnels(Full mesh)
FRR node
Protection NNHOP(for all Core routers)

FRR link
Protection NHOP
(for all POS interfaces
In Area 0.0.0.0)

OC48 POS
Interfaces
VoIP
Gateways

CoreRouters

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Network Investment & Growth One of the major challenge for Bell IP Network Designers is tomanage the ongoing investment/growth in the MPLS-IP
Infrastructure of new Service Areas (i.e. POP build out) while
managing the MPLS TE/FRR as Core Network Service Offering.
 Example of network impact when a site is added:
 New POS links
 Re-use existing IP addresses
 Optimize/Update routing path for existing primary and backup tunnels
 Design Fast Reroute plan for new network elements Bell Canada chose WANDL IP/MPLSview to automate its MPLS

TE/FRR Design and Engineering challenges

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Bell IP Engineering ChangeManagement Process
New network elements

Build Baseline

Update Baseline

Check impacton existing
TE elements

Update existing
primaryand backup tunnels

Add new primary
andFRR backup

Routerconfiguration

GenerateIOS configuration
For TE and FRR

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Step 1: Build and Crosscheck Baseline Baseline is built

via routerconfiguration files
as input.
 OSPF and RSVP

settings need tobe verified for
Quality Assurance
as they can have amajor impact on
the tunnel routing

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Step 2&3: Update Baseline and review theimpact of new network elements New network elements

contain new tunnels.
They may also turn theexisting FRR backuptunnels obsolete.
 IP/MPLSview Delta LSP

feature can
automatically identify theexisting Primary and
FRR tunnels that need
to be modified or are
now redundant.
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Step 4: Provisioning new primary tunnels
 Primary tunnels

are configured
with two path
options.

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Step 5: Provisioning Bell FRR backup
tunnels Fast Reroute backup

tunnels are calculated
for both Node and Link
Protection.
 FRR backup path does

not share any
router/site with primarytunnel path⇒ best in class network
protection.

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Step 6: Support FRR provisioning
 Best vehicle/language to communicate a TE/FRR Design to ourOperations team is in form of router commands.
 Wandl assists us in generating the related commands in a configlet.

interface Tunnel4
description from TORONTO to MONTREAL; protected link=TORONTO_POS0/0
ip unnumbered Loopback0
no ip directed-broadcast
tunnel destination 192.168.96.20
tunnel mode mpls traffic-eng
tunnel mpls traffic-eng path-option 10 explicit name Tunnel4.p0
tunnel mpls traffic-eng path-option 20 explicit name exclude_ 10.1.103.130!
interface POS0/0
dampeningip address 10.1.103.130 255.255.255.252
ip ospf cost 500
mpls label protocol both
mpls traffic-eng tunnels
mpls traffic-eng backup-path Tunnel422

Conclusion
 DiffServ-TE is a complex powerful mechanism totransport multimedia tunnels with many knobs to tune.
 DiffServ-TE networks tend to be large and multi-layer:

usually MPLS-TE, FRR are also deployed Hence manual configuration is very tedious and notscalable.
 The objective for Bell Canada IP Engineering Team is toautomate (i.e. OPEX Management) the MPLS-TE layerDesign/Management , there by using intelligent andcomplementing Software from vendors such as WANDL.

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Acknowledgement
We would like to acknowledge the following persons for their contributions
with implementing the MPLS TE in the Bell Canada network:

Shafik Hirjee
Hao-Hsin Huang
Tim LamMendy Valinsky
Mitch Paglia
Terry Snatinsky

Bell Canada
WANDL
Bell Canada
Bell Canada
Bell Canada
Bell Canada

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