MPLS VPN Implementation Configuring SmallScale Routing Protocols Between

Outline • Overview • Configuring PE-CE Routing Protocols • Selecting the VRF Routing Context for BGP • Configuring Per-VRF Static Routes • Configuring RIP PE-CE Routing • Configuring EIGRP PE-CE Routing • Configuring SOO for EIGRP PE-CE Loop Prevention • Summary © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -2

PE-CE Routing Protocols • PE-CE routing protocols are configured for individual VRFs. • Per-VRF routing protocols can be configured in two ways: – Per-VRF parameters are specified in routing contexts, which are selected with the address-family command. – A separate OSPF process has to be started for each VRF. • Prior to Cisco IOS Release 12. 3(4)T, the overall number of routing processes per router was limited to 32, of which only 28 were available for VRF assignment. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -3

Configuring the VRF Routing Context Within BGP Router(config)# router bgp as-number address-family ipv 4 vrf-name. . . Non-BGP redistribution. . . • Select the per-VRF BGP context with the address-family command. • Configure CE External Border Gateway Protocol neighbors in VRF context, not in global BGP configuration. • All non-BGP per-VRF routes have to be redistributed into a per-VRF BGP context to be propagated by MP-BGP to other PE routers. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -4

Configuring Per-VRF Static Routes Router(config)# ip route vrf-name prefix mask [interfacenumber] [next-hop-address] • This command configures per-VRF static routes. • The route is entered in the VRF table. • You must specify a next-hop IP address if you are not using a point-to-point interface. Sample router configuration: ip route vrf Customer_ABC 10. 0 255. 0. 0. 0 serial 0/0 10. 250. 0. 2 ! router bgp 65173 address-family ipv 4 vrf Customer_ABC redistribute static © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -5

Configuring RIP PE-CE Routing • A routing context is configured for each VRF running RIP. • RIP parameters have to be specified in the VRF. • Some parameters configured in the RIP process are propagated to routing contexts (for example, RIP version). • Only RIPv 2 is supported. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -6

Configuring RIP PE-CE Routing: RIP Metric Propagation Router(config)# router rip version 2 address-family ipv 4 vrf-name redistribute bgp as-number metric transparent • BGP routes must be redistributed back into RIP. • The RIP hop count has to be manually set for routes redistributed into RIP. • For end-to-end RIP networks, the following applies: – On the sending end, the RIP hop count is copied into the BGP MED. – On the receiving end, the metric transparent option copies the BGP MED into the RIP hop count, resulting in a consistent end-toend RIP hop count. • When you are using RIP with other protocols, the metric must be manually set. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -7

Configuring RIP PE-CE Routing: Example © 2006 Cisco Systems, Inc. All rights reserved. MPLS

Configuring EIGRP PE-CE Routing • Provides EIGRP with the capability to redistribute routes through a VPN cloud • Requires configuration of only the PE routers • Imposes no upgrade or configuration changes to customer equipment • Supports SOO capabilities to filter VPN traffic © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -9

Configuring EIGRP PE-CE Routing: EIGRP Metric Propagation Router(config)# router eigrp process-id address-family ipv 4 vrf-name autonomous-system as-number redistribute bgp as-number metric-value • Enables the EIGRP AS number of the CE under the address family. • Configures per-instance AS number. • Configures router redistribution. • External routes received without the configured metric are not to be advertised to the CE router. – The metric can be configured in the redistribute statement using the redistribute command or configured with the default-metric command. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -10

Configuring EIGRP PE-CE Routing: Example © 2006 Cisco Systems, Inc. All rights reserved. MPLS

Implementing EIGRP SOO for Loop Prevention © 2006 Cisco Systems, Inc. All rights reserved.

Implementing EIGRP SOO for Loop Prevention (Cont. ) • The SOO extended community can be used to prevent loops in dual-homed scenarios. • All PE routers supporting EIGRP MPLS VPNs must support the SOO extended community. • A unique SOO value must be configured for each VPN site. This value must be used on the PE-CE interface. • The SOO attribute is configured through a routemap command. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -13

Implementing EIGRP SOO for Loop Prevention (Cont. ) Router(config)# route-map name permit seq set extcommunity soo extended-community-value • Creates a route map that sets the SOO attribute Router(config-if)# ip vrf forwarding vrf-name ip vrf sitemap route-map-name ip address ip-address subnet-mask • Applies a route map that sets SOO extended community attribute to inbound routing updates received from this interface © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -14

Implementing EIGRP SOO for Loop Prevention (Cont. ) © 2006 Cisco Systems, Inc. All

Summary • The per-VRF routing protocols can be configured in two ways: as individual address families belonging to the same routing process or as separate routing processes. • Use the address-family ipv 4 vrf-name command to select the VRF routing context. • Use the ip route vrf command to establish static routes. • Use the address-family ipv 4 vrf-name command to start the configuration of individual routing context. • Use the redistribute command to configure the metric that is copied into the MED attribute of the BGP route. • Use the SOO extended community to prevent loops in EIGRP dual-homed scenarios. © 2006 Cisco Systems, Inc. All rights reserved. MPLS v 2. 2— 5 -16