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L3VPN Use case

Overview

This lab covers a L3VPN based on EVPN control-plane:

  • Sub-interface to connect to s1-ce03
  • Sub-interface to connect to s1-ce04
  • s1-ce03 and s1-ce04 are both connected to the same network ASN 65101.
  • s2-ce01 is connected based on a SVI interface with BGP session.

Technical details

Connectivity

CE node CE interface IP address IP address PE interface PE node
s1-ce03 Ethernet2.1203 10.2.0.1/31 10.2.0.0/31 Ethernet5.1203 s1-pe03
s1-ce04 Ethernet2.1203 10.2.0.3/31 10.2.0.2/31 Ethernet5.1203 s1-pe04
s2-ce01 Vlan1205 10.2.1.21/24 10.2.1.1/24 Vlan1205 s2-pe01

Routing Policy

Community Action
65000: 10110 local-preference 110
65000: 10090 local-preference 90

Configuration information

  • VRF ID: 12
  • Tenant supernet: 10.2.0.0/16
  • Announced prefix: 10.2.254.0/24
    • route-map s1-ce03: set community 65000:10090
    • route-map s1-ce04: set community 65000:10110

Snapshot

# ANTA to capture information
$ anta exec snapshot -o anta/l3vpn -c anta/snapshot-core-l3vpn.yml --tags core

Lab Scenario

Dual homed network with local-preference

Local Preference is updated with a route-map in at EVPN peers level according communities set on s1-ce*.

admin@s2-pe01# show bgp neighbors 10.255.0.1 evpn received-routes route-type ip-prefix 10.2.254.0/24

BGP routing table information for VRF default
Router identifier 10.255.1.5, local AS number 65000
BGP routing table entry for ip-prefix 10.2.254.0/24, Route Distinguisher: 10.255.1.3:12
 Paths: 1 available
  65101
    10.255.1.3 from 10.255.0.1 (10.255.0.1)
      Origin INCOMPLETE, metric -, localpref 90, weight 0, tag 0, valid, internal, best
      Originator: 10.255.1.3, Cluster list: 10.255.0.1
      Community: 65000:10090
      Extended Community: Route-Target-AS:12:12 TunnelEncap:tunnelTypeMpls
      MPLS label: 116385
BGP routing table entry for ip-prefix 10.2.254.0/24, Route Distinguisher: 10.255.1.4:12
 Paths: 1 available
  65101
    10.255.1.4 from 10.255.0.1 (10.255.0.1)
      Origin INCOMPLETE, metric -, localpref 110, weight 0, tag 0, valid, internal, best
      Originator: 10.255.1.4, Cluster list: 10.255.0.1
      Community: 65000:10110
      Extended Community: Route-Target-AS:12:12 TunnelEncap:tunnelTypeMpls
      MPLS label: 100001

OSPF as CE to PE for site02

Export BGP to OSPF and mark type-5/external with dn-bits / RFC4576

route-map RM-BGP-TO-OSPF permit 10
   description Redistribute BGP to OSPF
   match ip address prefix-list PL-ATM-FAKE-PREFIX
   set tag 1205
!
router ospf 1205 vrf ATM
   router-id 10.255.1.5
   passive-interface default
   no passive-interface Vlan1205
   redistribute bgp route-map RM-BGP-TO-OSPF
!

On s2-ce01:

router ospf 1205 vrf ATM
   no passive-interface Vlan1205
   dn-bit-ignore
!

And you can monitor LSDB state:

s2-ce01#show ip ospf database external vrf ATM

            OSPF Router with ID(10.2.1.21) (Instance ID 1205) (VRF ATM)


                 Type-5 AS External Link States

  LS Age: 393
  Options: (E DC DN)
  LS Type: AS External Links
  Link State ID: 10.2.254.0
  Advertising Router: 10.255.1.5
  LS Seq Number: 0x80000002
  Checksum: 0x7ddd
  Length: 36
  Network Mask: 255.255.255.0
        Metric Type: 2
        Metric: 1
        Forwarding Address: 0.0.0.0
        External Route Tag: 1205

s2-ce01#show ip route vrf ATM

VRF: ATM
Source Codes:
       C - connected, S - static, K - kernel,
       O - OSPF, IA - OSPF inter area, E1 - OSPF external type 1,
       E2 - OSPF external type 2, N1 - OSPF NSSA external type 1,
       N2 - OSPF NSSA external type2, B - Other BGP Routes,
       B I - iBGP, B E - eBGP, R - RIP, I L1 - IS-IS level 1,
       I L2 - IS-IS level 2, O3 - OSPFv3, A B - BGP Aggregate,
       A O - OSPF Summary, NG - Nexthop Group Static Route,
       V - VXLAN Control Service, M - Martian,
       DH - DHCP client installed default route,
       DP - Dynamic Policy Route, L - VRF Leaked,
       G  - gRIBI, RC - Route Cache Route,
       CL - CBF Leaked Route

Gateway of last resort is not set

 C        10.2.1.0/24
           directly connected, Vlan1205
 O E2     10.2.254.0/24 [110/1]
           via 10.2.1.1, Vlan1205