INTER-AUTONOMOUS SYSTEM MPLS VPN - APRICOT

30 Pages·2004·0.97 MB·English

INTER-AUTONOMOUS SYSTEM
MPLS VPN
February 2004
MPLS VPN Inter-AS,
2/04 ©2004 Cisco Systems, Inc. All rights reserved. 1
Agenda
• Inter-Autonomous System (Inter-AS) Multiprotocol
Label Switching (MPLS) VPN Overview
• Inter-AS Control and Forwarding Planes
• Inter-AS Connectivity Models
• Inter-AS Summary
MPLS VPN Inter-AS,
2/04 ©2004 Cisco Systems, Inc. All rights reserved. 2
MPLS VPNs review in one slide
VPN_A iBGP sessions VPN_A
10.2.0.0 11.5.0.0
CE
CE
VPN_B VPN_A
P P 10.1.0.0
10.2.0.0 PE PE CE
CE
VPN_A
11.6.0.0
P P
CE
VPN_B
PE CE
PE 10.3.0.0
VPN_B
CE
10.1.0.0
• P routers (LSRs) are in the core of the MPLS • Multiple routing tables (VRFs) are used on PEs
cloud
Each VRF contain customer routes
• PE routers use MPLS with the core and plain
Customer addresses can overlap
IP with CE routers
VPNs are isolated
• P and PE routers share a common IGP (LS)
• MP-BGP is used to propagate these addresses
• PE router are MP-iBGP fully meshed or use
between PE routers
Route-Reflectors
• Route Distinguishers (RD) are used to achieve
uniqueness of IP address (RD+IPv4=VPNv4)
• Route Targets are used to export and import
routes in a VPN
MPLS VPN Inter-AS,
2/04 ©2004 Cisco Systems, Inc. All rights reserved. 3
Why Inter-AS?
• Extends MPLS VPN services across geographical
boundaries, so Service Providers can support their
customer base in geographical locations that do not
have POPs
• Enables communication between networks under
separate autonomous systems (Service Providers)
• Provides traffic separation and maintain end-to-end
privacy while traffic traverses multiple MPLS VPN
backbones
MPLS VPN Inter-AS,
2/04 ©2004 Cisco Systems, Inc. All rights reserved. 4
Inter-AS Topology Overview
SShhaarreedd SSeerrvviicceess ffoorr VVPPNNss
Internet SShhaarreedd SSeerrvviicceess ffoorr VVPPNNss
Interne-GW
Interne-GW
PE-ASBR-2
AS #100
AS #200
PE-ASBR-1
PE-2
PE-1 VPN-R-3
Spoke
CE-R1
CE-B2 CE-3 CE-4
CE-B1
VPN-R-1
HUBv VPN-G-1 VPN-G-2
VPN-B-2
VPN-B-1
VPN-R-2
Spoke
SShhaarreedd SSeerrvviicceess ffoorr VVPPNNss SShhaarreedd SSeerrvviicceess ffoorr VVPPNNss
MPLS VPN Inter-AS,
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Inter-AS Functionality
• MPLS VPN providers exchange routes across
VRF interfaces
• Each PE-ASBR router treats the other as a CE
• Provider edge routers are gateways used for VPNv4
route exchange
• PE-ASBR to PE-ASBR link may use any supported
PE-CE routing protocol
MPLS VPN Inter-AS,
2/04 ©2004 Cisco Systems, Inc. All rights reserved. 6
Routing For Each SP AS
• Each AS runs a different IGP and no IGP routing
information exchange between the domains
• All routing information exchange between the
domains is via Exterior Routing Protocol
• Routing policies may differ between the exchange
points
• Customer VPN routes are distributed into VRFs at
the ingress PE of the ISP
• Each PE assigns labels for the routes to establish
connections
MPLS VPN Inter-AS,
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INTER-AS Control and Data Planes
MPLS VPN Inter-AS,
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Inter-AS Control Plane
• Establishes EBGP session between the PE-ASBRs
• Distribute IPv4 routes for the VPNs in the form of VPNv4
addresses
• PE-ASBRs re-write Next-hop and labels when a route is
distributed to a neighbor
• PE-ASBRs store ALL VPN routes that need to be
exchanged
• Routes are in the MP-BGP table but not in any other
routing tables
PE-ASBRs do not have any VRF
MP-eBGP labels are used in LFIB
MPLS VPN Inter-AS,
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Inter-AS Route Exchange
Route=VPN Blue Site1 Route=VPN Blue Site1
Via: Via:
Static Static
EBGP EBGP
OSPF OSPF
EIGRP EIGRP
RIPv2 RIPv2
ASBR-SP1 ASBR-SP2
PE1-SP2 CE-B-2
CE-B-1 PE1-SP1
SP1 SP2
MPLS Core MPLS Core
IBGP IBGP
EBGP
Route=Site2 Route=Site2
Route=Site2
Next hop=ASBR-SP2 Next hop=PE1-SP2
Next hop=ASBR-SP2
Label=L’ Label=L’
Label=L’
MPLS VPN Inter-AS,
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