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1 © 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 INTER-AUTONOMOUS SYSTEM MPLS VPN: ADVANCED CONCEPTS December 2003

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1 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 INTER-AUTONOMOUS SYSTEM MPLS VPN: ADVANCED CONCEPTS December 2003 Slide 2 2 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Routing between sub-autonomous systems Inter-AS scaling Inter-AS filtering and route distribution Load balancing RT rewrite Services in Inter-AS Inter-AS and CSC comparison Inter-AS Summary Agenda Slide 3 3 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 ROUTING BETWEEN SUB-AUTONOMOUS SYSTEMS 33 2003 Cisco Systems, Inc. All rights reserved. Presentation_ID Slide 4 4 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Separate IGPs Each sub-confederations runs a single IGP Route-reflectors are used as peering points between sub-confederations for better scaling Next-hop self done by border routers on eBGP and iBGP sessions towards intra-confederation peers Confederation Multiple IGP Domains Slide 5 5 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 PE-1 CEGBP-1 CE-2 CEGBP-2 PE-3 CE-1 PE-2 CE-5 CE-4 CE-3 Core of P LSRs Confederation Sub-AS1 with IGP-1 Sub-AS2 with IGP-2 MP-eBGP intra confederation for VPNv4 routes with label distribution PEs exchange VPNv4 addresses with labels Next-hop and labels are changed (next-hop self is used) PE1 and PE-2 addresses are known in both IGPs MP-iBGP Confederation Multiple IGP Domains Slide 6 6 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 PE-1 CEGBP-1 CE-2 CEBGP-2 PE-3 CE-1 PE-2 CE-5 CE-4 CE-3 Core of P LSRs Confederation Sub-AS1 with IGP-1 Sub-AS2 with IGP-2 Network=N Next-hop=CE2 Network=N Next-hop=PE3 Network=RD1:N Next-hop=PE1 Label=L1 Network=RD1:N Next-hop=RR1 Label=L2 Network=RD1:N Next-hop=RR2 Label=L3 Confederation Multiple IGP Domains (Cont.) Slide 7 7 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Route reflectors exchange routes Using Route reflectors is a natural approach since they already have all VPN routes Next-hop-self choices Option-1: eBGP only Option-2: eBGP and iBGP on border routers When next-hop self is used on both iBGP and eBGP sessions (in CEBGP-1 and CEBGP-2) the topology is similar to a Multi-provider-VPN topology Confederation Multiple IGP Domains: Important Points Slide 8 8 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Confederation Multiple IGP Domains: Important Points (Cont.) CEBGP-1 and CEBGP-2 each need to be known in both IGPs CEBGP-1 and CEBGP-2 use interface addresses for their BGP session Label has to be bound on peer address; single label is used between sub-confederations Neighbor route needs to be known either a static router, or by using PPP neighbor-route discovery Implementation will create a neighbor route for the BGP peer address Slide 9 9 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 SCALING INTER-PROVIDER SOLUTIONS 99 2003 Cisco Systems, Inc. All rights reserved. Presentation_ID Slide 10 10 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 PE-ASBR Memory Consumption VPNv4 MP-iBGP Sessions PE-ASBR Memory No. VPN Routes Memory Consumption Slide 11 11 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 PE-ASBR Memory Scaling Potentially large amounts of VPN routing information that may not need to be carried on PE-ASBRs Large percentage will be local VPN prefixes PE-ASBRs must hold relevant VPN routing information such as VPN prefix details Two methods available to aid scaling ARF with local VRF import ARF disabled with inbound filtering Slide 12 12 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 ARF with Local VRF Import Automatic Route Filtering (ARF) for non-imported routes If RT does not match locally configured import statement then drop the route Each PE-ASBR holds VRFs for Inter-AS VPNs and imports routes based on RT values PE-ASBR acts like normal PE routers with MP-eBGP sessions Slide 13 13 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 BGP Memory VRFs CEF Memory MPLS Memory Routing Table Memory MP-iBGP VPNv4 Automatic Route Filtering BGP, CEF, MPLS & RT Memory per-VRF ARF with Local VRF Import (Cont.) Slide 14 14 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 ARF Disabled With Inbound Filtering Automatic Route Filtering (ARF) enabled by default if no VRFs are configured then ALL VPN routes are dropped by the PE-ASBR Automatic Route Filtering may be disabled with no default BGP route-target filter command within the BGP configuration Disabling of ARF will cause ALL routes to be accepted by the PE-ASBR Additional filtering mechanisms should be used to drop unwanted routes Slide 15 15 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 BGP Memory MP-iBGP VPNv4 NO Automatic Route Filtering NO per-VRF CEF or RT Memory, only BGP & LFIB router bgp 1 ! no bgp default route-target filter ! address-family vpnv4 neighbor 154.27.0.134 activate neighbor 154.27.0.134 send-community extended neighbor 154.27.0.134 route-map vpn-routes-filter in LFIB Memory VRF & CEF memory not required Routing Table memory not required ARF Disabled With Inbound Filtering (Cont.) Slide 16 16 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Next-Hop-Self Effect On LFIB BGP Memory 1000 prefixes MP-iBGP VPNv4 Next-hop-self increase amount of LFIB entries on receiving PE-ASBR LFIB Memory 1000 prefixes With NHS Without NHS BGP Memory 1000 prefixes LFIB Memory 1000 prefixes BGP Memory 1000 prefixes LFIB memory 1 prefix for BGP next- hop 1000 prefixes in total Slide 17 17 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 FILTERING AND ROUTER DISTRIBUTION MECHANISMS Slide 18 18 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Various Filtering Points In Inter-AS PE RR 2. Outbound filtering per-peer 4. Inbound filtering per-peer OR rr-group 1. Inbound filtering on PE-ASBR 3. Automatic route filtering inbound AS #100 AS #200 RR AS #300 PE 5. Automatic route filtering inbound Slide 19 19 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Inbound Filtering On PE-ASBR BGP Memory RT 214:27 NO Automatic Route Filtering NO ARF Filter inbound on per-peer basis router bgp 1 ! no bgp default route-target filter ! address-family vpnv4 neighbor 154.27.0.134 activate neighbor 154.27.0.134 send-community extended neighbor 154.27.0.134 route-map vpn-routes-filter in ! ip extcommunity-list 1 permit rt 214:27 rt 214:94 ! route-map vpn-routes-filter permit 10 match extcommunity 1 LFIB Memory RT 214:94 Blue VPN routes discarded RT 214:129 Slide 20 20 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Outbound Filtering On PE-ASBR BGP Table address-family vpnv4 neighbor 157.27.0.132 route-map MPeBGP-2 out neighbor 149.27.0.142 route-map MPeBGP-3 out ! route-map MPeBGP-2 permit 10 match extcommunity 214:27 ! route-map MPeBGP-3 permit 10 match extcommunity 214:94 RED VPN GREEN VPN AS #300 AS #200 Slide 21 21 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Downstream RT Allocation Inbound and outbound filtering are restrictive with a large number of VPN clients Each RT must be known, and the filters must be established Changes to VPN client membership will cause configuration changes on PE-ASBRs Each filter must be updated to reflect the addition/deletion of VPN clients Simplified filtering scheme is needed with a large number of clients Provided with downstream provider RT allocation scheme Slide 22 22 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 RED VPN AS #300 RT 129:102 AS #100 GREEN VPN RED VPN RT 129:12090 GREEN VPN RT 129:12001 address-family vpnv4 neighbor 154.27.0.134 activate neighbor 154.27.0.134 send-community extended neighbor 154.27.0.134 route-map asbr-routes-filter in neighbor 157.27.0.132 route-map MPeBGP-2 out neighbor 149.27.0.142 route-map MPeBGP-3 out ! ip extcommunity-list 1 permit rt 129:101 rt 129:102 ip extcommunity-list 16 permit rt 129:101 ip extcommunity-list 17 permit rt 129:102 Export RT 129:12090 RT 129:102 Export RT 129:12001 RT 129:101 AS #200 RT 129:101 route-map asbr-routes-filter permit 10 match extcommunity 1 ! route-map MPeBGP-2 permit 10 match extcommunity 16 ! route-map MPeBGP-3 permit 10 match extcommunity 17 Downstream RT Allocation (Cont.) Slide 23 23 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 LOAD BALANCING: DISTRIBUTION OF TRAFFIC LOAD BETWEEN PROVIDERS Slide 24 24 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Balancing of Inter-AS traffic is an important issue for distribution of traffic and redundancy of network design All Inter-AS traffic must pass through PE-ASBRs As BGP next-hops are reachable via these routers Multiple links provide traffic distribution These do not provide redundancy due to single point of failure of the PE-ASBR Load Balancing Between Backbones Slide 25 25 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 VPN Client Traffic Flow PE-1 PE-2 VPN-B CE-2 CE-3 VPN-B PE-ASBR-1 PE-ASBR-2 152.12.4.0/24 BGP, OSPF, RIPv2 152.12.4.0/24,NH=CE-2 VPN-v4 update: RD:1:27:152.12.4.0/24, NH=PE-1 RT=1:222, Label=(L1) VPN-v4 updates: NH=PE-ASBR-1 VPN-v4 updates: NH=PE-ASBR-2 ALL Inter-AS traffic flows across PE- ASBR-2 to PE- ASBR-1 link VPN Client to VPN Client traffic flow via Inter-AS Link Slide 26 26 2003 Cisco Systems, Inc. All rights reserved. MPLS VPN Inter-AS, 12/03 Load Balancing Between PE-ASBRs PE-ASBR-1 Network Y BGP NH=PE-ASBR-2 LO0 Network Y BGP NH=PE-ASBR-2 LO0 Network Y PE-ASBR-2 Loopback Interface BGP peering (Multi-HOP MP-eBGP) between loopbacks Routing Table PE-ASBR-2 LO0 via 193.1.1.9 via 193.1.1.13 via 193.1.1.17 Routing Table PE-ASBR-2 LO0 via 193.1.1.9 via 193.1.1.13 via 193.1.1.17 193.1.1.9 1