Hierarchical VPNs,
Neighbor Discovery and
Broadcast Links in Virtual
Router Approach
Karthik Muthukrishnan
Senior Consulting Engineer
Thomas Walsh
Principal Network Consultant
Lucent Technologies
26 April 2001
©2001, Lucent Technologies
IP VPN Motivation
Realization of multiple private,
geographically dispersed IP Networks
(transparent and secure private IP
interconnection) over a shared provider
infrastructure
26 April 2001
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IP VPNs
Motivation
IP MPLS VPNs Emulate a Private
Network Over a Shared IP Network
Branch/
Regional
Offices
Remote
Workers
Shared IP
Network
Internet
Corporate
Headquarters
Customers,
Suppliers
• Layer 3 - Any to Any connectivity
• Security, reliability, performance, management
• No manual configuration of PVCs or tunnels
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Multiple IP VPNs
Physical Topology View
Customer A
Headquarters
Customer B
Dallas Branch
CE Router
Customer B
Headquarters
Logical VPN View
CE Router
CE Router
HQ
PE
PE
VNP 20000
VNP 100
VNP 10
VNP 100
Boston
VNP 1000
LA
VNP 10
VNP 20000
P
VNP 100
P
PE
HQ
PE VNP 20000
VNP 10000
VNP 10
VNP 10
CE Router
Customer B
LA Branch
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Customer A
VPN
CE Router
VNP 10
Customer A
LA Branch
VNP
10
CE Router
Customer A
Boston Branch
Customer B
VPN
Dallas
LA
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IP VPN Features
•
•
•
•
•
•
•
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Private Addressing
Intranet
Extranet
Privacy
Multiple sites
Traffic engineering
IP enabled services
(including voice)
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What are Virtual Routers?
• Each Virtual Router (VR) is a cross sectional slice of
the hardware and software resources.
• Each VR is NOT a separate operating system“task”
• Resides only at edge of SP network
• Logically equivalent to a physical router (filters,
interfaces, routing ports, access lists, configuration,
management, monitoring,)
• VRs and physical routers in a VPN represent a
private routing domain with defined points of
connection to the rest of the world
• VRs discover each other in the same way physical
routers discover each other over a LAN
• Use standard link level multicast
• No need for an additional membership discovery scheme
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Hierarchical VPNs
[Carrier’s carrier]
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IP VPN - Green Foods
Paris Office
Green Foods
Berlin Office
Green Foods
Remote
Workers
PSTN/Cable/DSL/Wireless
Boston Office
Green Foods
26 April 2001
Omni Present
Provider
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IP VPN - Red Foods
London Office
Red Foods
Omni
Present
Provider
PSTN/DSL/Cable/
Wireless
26 April 2001
Internet
Paris Office
Red Foods
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Problem Statement
• Omni present provider rarely present..
• Regional providers provide last mile
service
• National/International carriers provide
global connectivity
• Need bridge to connect regional and
global carriers
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Hierarchical VPNs - Business Model
Paris Office
Green Foods
London Office
Red Foods
London Provider
Paris Provider
International
Provider
Paris Office
Red Foods
Berlin Provider
Boston Provider
Berlin Office
Green Foods
Boston Office
Green Foods
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Hierarchical VPNs - Network Model
Paris Office
Green Foods
London Office
Red Foods
London Provider
VR
VR
VR
Paris
Provider
VR
VR
VR VR
VR
International
Provider
VR
VR
Paris Office
Red Foods
VR
VR
VR
Boston Provider
VR
VR
Berlin Provider
VR
VR
VR
Berlin Office
Green Foods
Boston Office
Green Foods
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Multi-Level Hierarchical VPNs
Level 1 VPNs
Level 0 VPN
Level 1 VPNs
VPN X
VPN X
VPN Y
VPN Y
VPN A
VPN Z
VPN Z
Data within a Level 1 VPN is transported transparently across the Level 0 VPN
Hierarchies can be extended to more than two Levels
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Hierarchical VPNs
Paris Office
Green Foods
London Office
Red Foods
London Provider
VR
VR
VR
Paris
Provider
VR
VR
VR
International
Provider
VR
VR
VR
VR
Paris Office
Red Foods
VR
VR
VR VR
Boston Provider
VR
Berlin Provider
VR
VR
VR
Berlin Office
Green Foods
Boston Office
Green Foods
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VPN LSP Tunnels
VR
VR
VR
VR
Purple VPN’s LSP Tunnel
VR
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Inter VR Links
VR
VR
VR
VR
Level 1 VPN
Level 2 VPN
Level 2 VPN
VR
VR
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Inter VR Links
• Supports hierarchical relationship
• Level 1 .. Level 2 .. Level N VPNs
• Supports peering relationship
• Internet connectivity
• Inter VPN [controlled] connectivity
– Controlled by standard routing policies at both
ends
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Neighbor Discovery via
Broadcast Links
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Neighbor Discovery
Customer A
Branch (Boston)
Parts DB
165.1.1.1
Switch-B Backbone
address =150.202.77.2
VR-B
Service Provider’s
Network
IP Interface
(150.1.1.2)
IP Interface
(150.1.1.1)
Inter VR Broadcast Link
VR-A
Switch-A Backbone
address =
150.202.78.12
VR-C
IP Interface
(150.1.1.3)
Switch-C internal
Backbone address =
150.202.79.12
Customer A’s
Vendor
Customer A
HQ (Chicago)
185.1.1.1
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© 2001, Lucent Technologies
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For more information
• Muthukrishnan, K. et al, “A Core MPLS IP VPN Architecture”,
RFC-2917, September 2000
• Muthukrishnan, K. et al, “A Core MPLS IP VPN Architecture”,
<draft-muthukrishnan-rfc2917bis-00.txt>, work in progress
in IETF
• Kathirvelu, C. et al, “A Core MPLS IP VPN Link Broadcast
and Virtual Router Discovery”,
<draft-kathirvelu-corevpn-disc-00.txt>,
work in progress in IETF
• Kathirvelu, C. et al, “Hierarchical VPN over MPLS
Transport”, <draft-kathirvelu-hiervpn-corevpn-00.txt>,
work in progress in IETF
• Draft ITU-T Recommendation Y.1311.1, Network Based IP
VPN over MPLS Architecture
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Thank you!
Karthik Muthukrishnan
mkarthik@lucent.com
26 April 2001
Thomas Walsh
tdwalsh@lucent.com
© 2001, Lucent Technologies
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