Traffic Engineering

Traffic Engineering

in MPLS based

in MPLS based

VPNs

VPNs

Naganand Doraswamy (PhotonEx

Naganand Doraswamy (PhotonEx

Corp),

Corp),

Shantigram Jagannath,

Shantigram Jagannath,

Presented by Don Fedyk

Presented by Don Fedyk

March 2000

March 2000

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MPLS Forum March 2000

Outline

•

IP VPN

•

IP VPN and MPLS

•

IP VPN Traffic Engineering

•

MPLS Traffic Engineering

•

Combining IP VPNs and MPLS TE

•

Conclusion

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MPLS Forum March 2000

IP VPNs : It’s all a matter of

perspective

!

Service Provider’s

Nirvana

:

Customer outsource their entire IP
Network and Services to a

single

Service Provider

.

Equipment Provider's

Nirvana

:

Service Provider buys their

entire IP

Network from a

single

Equipment

Provider

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MPLS Forum March 2000

IP VPNs It’s

NOT

simple!

The

Customer Reality!



Has existing IP Network deployed
with CPE, Campus Backbones



May have a private address plan



Application types vary over time
between areas of the network e.g.
multi-protocol, voice



Will implement some Enterprise-
based IP VPN services

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MPLS Forum March 2000

There are

more requirements

!



May use a private WAN (TDM, FR,
ATM) & some public non-IP WAN
services (ISDN, PSTN, T1, SONET,
FR, ATM.)



Membership of VPNs will change
over time: Intranet, Internet,
Extranet



Wants Standards and Multiple Vendors

for Reliability and Cost Efficiency



May outsource IP VPN Services on a
location basis to several Service
Providers

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MPLS Forum March 2000

Standards for IP VPNs

•

Largely Do Not Exist

•

A Few Informational RFCs

—

RFC 2547, RFC 2764

•

Over the last few years:

•

Lots of drafts

—

VPN, MPLS, Policy...

•

Many Industry Players

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MPLS Forum March 2000

IP VPN Landscape

•

Routing & Addressing

—

Handle overlapping addresses

—

IP VPN Extensions to Routing Protocols

–

Virtual Router’s or BGP extensions

—

Forwarding support

•

Traffic Engineering and QoS

—

Guarantee bandwidth and other traffic requirements

—

Optimize network resource utilization

•

Management

—

Network Management

—

Policy Management

•

Security

—

Traffic segregation

—

Encrypting/Authenticating packets

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MPLS Forum March 2000

Site

Terminology Refresher

• Set of “Sites” attached to a common network
(“backbone”), through Provider Edge (PE) routers.

• IP VPN: Subsets of the Set of sites.
• Two sites have IP connectivity over the backbone
only if there is a IP VPN that contains them both.

• A site may belong to more than one IP VPN.

CE: Customer Edge device
PE: Provider Edge Router
P: Provider (Backbone
Router)

CE: Customer Edge device
PE: Provider Edge Router
P: Provider (Backbone
Router)

Site

Site

Site

Site

Site

Site

Site

P

P

P

P

P

Provider (IP/MPLS)Backbone

PE

PE

PE

PE

P

P

P

P

P

CE

CE

CE

CE

CE

CE

CE

CE

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MPLS Forum March 2000

VPN Types:

L2 VPNs

—

X.25 CUGS

—

Frame Relay

—

ATM

IP VPN Types (RFC 2764)

—

Virtual Leased Lines (VLL)

—

Virtual Private Routed Network (VPRN)

—

Virtual Private Dial Networks (VPDN)

—

Virtual Private LAN Segment (VPLS)

Types of Tunnels

•

L2

•

IP

•

IPSec

•

MPLS

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MPLS Forum March 2000

Why MPLS Tunnels?

•

MPLS is an efficient tunnel technology

•

MPLS is IP centric

•

MPLS is L2 agnostic

•

MPLS LSPs are connection oriented

•

MPLS LSPs can be Stacked

•

MPLS offers Traffic Engineering

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MPLS Forum March 2000

Virtual Transport Network using

MPLS

(VPRN)

Carrier Network

Customer

xxx

a

xxxa

xxxa

xxx

a

Customer

Packet

Encapsulation

“Stack”

Transport

De-Encapsulation Customer

Packet

Here or Here

Here or Here

L1

L1

“VPN + Port”

L2

L2

Destination PE + QoS

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MPLS Forum March 2000

Virtual Transport Network using

MPLS

Carrier Network

Customer

Routing Interface

•

Static

•

IGP

•

BGP

VPN Routing

•

Virtual BGP, IGP (inband)

•

BGP-4 + Extensions (out of band)

VPN Routing

Network looks like a Router

from the customer view

Here or Here

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MPLS Forum March 2000

Customer A

Customer C

VR1

VR2

VR n

BGP4

Customer B

Customer A

Customer C

MPLS

Customer B

BGP4+

Extensions

Info RFC 2547

Info RFC 2764

ATM

MPLS

Virtual routers

in a single switch

—

Each instance dedicated to a

single customer with separate

routing and forwarding tables

—

Standard IP routing to customer

—

Standard IP routing in the core

network, BGP4

—

Core independent, ATM, IP, MPLS

Multiple

indexed tables

in a

single switch

—

One BGP4 process with

extensions for VPNs

—

Standard IP routing to

customer, no OSPF

—

Extended BGP4 routing into

the core network

—

Hierarchical MPLS routing

required in the core

network

Techniques for Overlapping

Addresses

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MPLS Forum March 2000

Virtual Transport Network MPLS

Label Distribution

Implicit:

Implicit:

LDP is the MPLS

LDP is the MPLS

protocol for implicitly

protocol for implicitly

assigning labels

assigning labels

based upon the ‘hop

based upon the ‘hop

by hop’ path chosen

by hop’ path chosen

by the Service

by the Service

Provider’s IGP in the

Provider’s IGP in the

base network

base network

Implicit:

Implicit:

LDP is the MPLS

LDP is the MPLS

protocol for implicitly

protocol for implicitly

assigning labels

assigning labels

based upon the ‘hop

based upon the ‘hop

by hop’ path chosen

by hop’ path chosen

by the Service

by the Service

Provider’s IGP in the

Provider’s IGP in the

base network

base network

Explicit traffic

Explicit traffic

placement:

placement:

CR-LDP or Extended

CR-LDP or Extended

RSVP can be used to

RSVP can be used to

place a LSP through

place a LSP through

designated core

designated core

LSR’s and assign the

LSR’s and assign the

corresponding labels

corresponding labels

to the VPN traffic

to the VPN traffic

Explicit traffic

Explicit traffic

placement:

placement:

CR-LDP or Extended

CR-LDP or Extended

RSVP can be used to

RSVP can be used to

place a LSP through

place a LSP through

designated core

designated core

LSR’s and assign the

LSR’s and assign the

corresponding labels

corresponding labels

to the VPN traffic

to the VPN traffic

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MPLS Forum March 2000

VPN Traffic Engineering Models

•

There are two models:

—

Between two end points i.e. On a pair-wise basis between
edge routers

—

Between an origin and a set of destinations

•

The two models can be abstracted into

—

Pipes: Provides performance guarantee for traffic between a
<src, dst> pair. It is very similar to a leased line.

—

Hoses: Provides performance guarantee between an origin
and a set of destinations both inbound and outbound

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MPLS Forum March 2000

PIPE Example

•

Pipe Model is analogous to the Layer 2 Model

—

Offers ability to control End to End QoS

CE

P

PE

PE

PE

P

P

P

CE

CE

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MPLS Forum March 2000

Hose Example

•

Hose Model

—

Traffic in the provider cloud to satisfy A+B traffic to C

CE

PE

PE

CE

CE

PE

A

B

C

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MPLS Forum March 2000

MPLS Traffic Engineering

•

How Label Switch Paths (LSPs) are built

—

Constraint-based Routing (CR)

•

How traffic maps on to LSPs

—

What criteria is used

•

How LSPs are maintained

—

Failure recovery

—

Optimization

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MPLS Forum March 2000

MPLS Constraint-Based Routing

Functions

Path

Selection

IS-IS

TE-Extensions

OSPF

TE-Extensions

CR-LDP

TE

Database

Bandwidth

Manager

TE

Policy Manager

RSVP-TE

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MPLS Forum March 2000

Elements of MPLS Constraint Based

Routing

•

Distribution of link loading and
administrative information

—

Use the IGP(OSPF/IS-IS) to distribute this information

—

Attributes related to link capacity like link bandwidth,
maximum reservable bandwidth at different setup/holding
priorities, current reserved bandwidth, are advertised

—

Administrative policies are carried via link color attribute

•

Path Selection Algorithm

—

Computes path that enforces the constraints

—

Constraints supplied may include bandwidth
requirements, maximum number of hops, exclusion of
certain links, etc.

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MPLS Forum March 2000

Elements of MPLS Constraint Based

Routing

•

Setup of traffic engineered path

—

CR-LDP or RSVP-TE can be used as a signaling mechanism
to establish paths.

—

Link Admission Control to reserve resources for the path

—

PNNI like crank-back mechanism for feedback on tunnel
setup

—

Can be activated/deactivated dynamically

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MPLS Forum March 2000

MPLS Traffic Engineering

•

Provides traffic placement and
performance guarantees

•

Pipes readily map to LSPs to guarantee
performance

•

Merging capabilities of MPLS allows
scalable way to implement the hose
model

•

Automatic path setup allows recovery
from failure and optimization

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MPLS Forum March 2000

LSP Setup and Mapping Traffic

•

Criteria used to setup and map traffic to LSPs

—

IP Traffic

–

Destination address prefix

–

Source/Destination Address Prefix

–

Application type

–

QoS requirement(DS Field/EXP Field)

–

BGP Next-hop

—

Context Sensitive

–

L2

–

Labels

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MPLS Forum March 2000

MPLS Class of Service (CoS)

•

MPLS provides CoS

—

This is achieved by using L-LSP’s or E-LSP’s

—

L-LSP’s are used when a separate label is used to identify
each CoS within a VPN

—

E-LSP is used when the EXP bits in the labels are used to
identify the CoS within a VPN

E-

LSP

Link

L-

LSP

Link

CoS

CoS

MPLS LSP Cross Sections

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MPLS Forum March 2000

Does MPLS TE + MPLS VPN = VPN

TE ?

MPLS LSP Cross Section

•

TE between LSP

•

CoS within LSP

E-

LSP

MPLS LSP Cross Section

•

TE between LSP

•

CoS within LSP

•

VPNs across a CoS

CoS

CoS

VPNaVPNbVPNcVPNd

CoS

Possibly…

But it adds one more dimension

to the problem

Link

E-LSPs

or

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MPLS Forum March 2000

MPLS IP VPN TE Benefits ISP

Perspective

•

Optimizes network resource usage

•

Traffic Engineering features to provide advanced
services

•

Dedicated Bandwidth for VPNs between two sites

—

VLL like service

•

Setup LSPs for carrying aggregated premium
traffic

—

L-LSPs and E-LSPs can be combined

•

Dynamically change bandwidth on the LSPs

—

draft-ietf-mpls-crlsp-modify-00.txt

•

Provides Service equivalent Layer 2 Technologies

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MPLS Forum March 2000

Using Traffic Engineered Tunnels for

VPNs

CE2

CE1

P

PE2

PE1

PE3

Voice VPN

BE VPN

Voice VPN

BE VPN

802.1Q

P

P

P

•

The Best Effort VPN (blue) and the voice VPN (red)

take divergent paths on the network

•

The red path is optimized through traffic engineering

for low latency applications

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MPLS Forum March 2000

Conclusions

•

IP VPNs are maturing but not Standard yet

•

IP VPN provides a spectrum of TE scenarios

•

MPLS TE is deploying based on IP

•

IP VPN + MPLS TE need to be harmonized to
provide a deployable service

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MPLS Forum March 2000

Thank You!