MPLS VPN Implementation Configuring an MPBGP Session Between
MPLS VPN Implementation Configuring an MP-BGP Session Between PE Routers © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -1
Outline • Overview • Configuring BGP Address Families • Enabling BGP Neighbors • Configuring MP-BGP • Configuring MP-IBGP • Configuring MP-BGP Community Propagation • Disabling IPv 4 Route Exchange • Summary © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -2
Configuring BGP Address Families • The BGP process in an MPLS VPN-enabled router performs three separate tasks: – Global BGP routes (Internet routing) are exchanged as in traditional BGP setup. – VPNv 4 prefixes are exchanged through MP-BGP. – VPN routes are exchanged with CE routers through per. VRF External Border Gateway Protocol sessions. • Address families (routing protocol contexts) are used to configure these three tasks in the same BGP process. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -3
Configuring BGP Address Families (Cont. ) Router(config)# router bgp as-number • Selects global BGP routing process Router(config-router)# address-family vpnv 4 • Selects configuration of VPNv 4 prefix exchanges under MP-BGP sessions Router(config-router)# address-family ipv 4 vrf-name • Selects configuration of per-VRF PE-CE EBGP parameters © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -4
BGP Neighbors • MP-BGP neighbors are configured under the BGP routing process: – These neighbors need to be activated for each global address family that they support. – Per-address-family parameters can be configured for these neighbors. • VRF-specific EBGP neighbors are configured under corresponding address families. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -5
Configuring MP-BGP MPLS VPN MP-BGP configuration steps: • Configure MP-BGP neighbor under BGP routing process. • Configure BGP address family VPNv 4. • Activate configured BGP neighbor for VPNv 4 route exchange. • Specify additional parameters for VPNv 4 route exchange (filters, next hops, and so on). © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -6
Configuring MP-IBGP Router(config)# router bgp as-number neighbor ip-address remote-as as-number neighbor ip-address update-source interface-type interface-number • All MP-BGP neighbors have to be configured under global BGP routing configuration. • MP-IBGP sessions have to run between loopback interfaces. Router(config-router)# address-family vpnv 4 • This command starts configuration of MP-BGP routing for VPNv 4 route exchange. • The parameters that apply only to MP-BGP exchange of VPNv 4 routes between already configured IBGP neighbors are configured under this address family. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -7
Configuring MP-IBGP (Cont. ) Router(config-router-af)# neighbor ip-address activate • The BGP neighbor defined under BGP router configuration has to be activated for VPNv 4 route exchange. Router(config-router-af)# neighbor ip-address next-hop-self • The next-hop-self keyword can be configured on the MP-IBGP session for MPLS VPN configuration if EBGP is being run with a CE neighbor. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -8
MP-BGP Community Propagation Router(config-router-af)# neighbor ip-address send-community [standard | extended | both] • This command with the extended option is enabled by default by Cisco IOS software after the BGP neighbor has been activated for VPNv 4 route exchange. • The command can be used to enable propagation of standard BGP communities attached to VPNv 4 prefixes. • Usage guidelines: – Extended BGP communities attached to VPNv 4 prefixes have to be exchanged between MP-BGP neighbors for proper MPLS VPN operation. – To propagate standard BGP communities between MP‑BGP neighbors, use the both option. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -9
MP-BGP Community Propagation (Cont. ) © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -10
Disabling IPv 4 Route Exchange Router(config-router)# no bgp default ipv 4 -unicast • The exchange of IPv 4 routes between BGP neighbors is enabled by default—every configured neighbor will also receive IPv 4 routes. • This command disables the default exchange of IPv 4 routes—neighbors that need to receive IPv 4 routes have to be activated for IPv 4 route exchange. • Use this command when the same router carries Internet and VPNv 4 routes and you do not want to propagate Internet routes to some PE neighbors. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -11
Disabling IPv 4 Route Exchange (Cont. ) • Neighbor 172. 16. 32. 14 receives only Internet routes. • Neighbor 172. 16. 32. 15 receives only VPNv 4 routes. • Neighbor 172. 16. 32. 27 receives Internet and VPNv 4 routes. router bgp 65173 no bgp default ipv 4 -unicast neighbor 172. 16. 32. 14 remote-as 65173 neighbor 172. 16. 32. 15 remote-as 65173 neighbor 172. 16. 32. 27 remote-as 65173 ! Activate IPv 4 route exchange neighbor 172. 16. 32. 14 activate neighbor 172. 16. 32. 27 activate ! Step#2 – VPNv 4 route exchange address-family vpnv 4 neighbor 172. 16. 32. 15 activate neighbor 172. 16. 32. 27 activate © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -12
Summary • Use the address-family command to select the routing context that you want to configure. • Use the router bgp command to configure the BGP routing process, and configure VRF-specific EBGP neighbors under corresponding address families. • To configure MPLS VPN MP-BGP, you need to: – Configure MP-BGP neighbors. – Configure MP-BGP address family to start VPNv 4 routing. – Activate configured MP-BGP neighbors. – Specify additional parameters for VPNv 4 route exchange. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -13
Summary (Cont. ) • These commands are used to configure MP-IBGP: – neighbor remote-as – neighbor update-source – neighbor activate – neighbor next-hop-self • Use the neighbor send-community command to support standard and extended communities. • There are two ways to disable IPv 4 route exchange: – no neighbor activate command – no bgp default ipv 4 -unicast command. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -14
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -15
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