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MPLS Layer 3 VPN VRFs and Redistribution - part2

This is part 2 of 2. My shortish summarized version of MPLS Layer 3 VPN VRFs and Redistribution.





Virtual Routing and Forwarding (VRF) Instances:

  • VRF Name: AS:THECOMPANY
  • Route Distinguisher: AS:NUMBER or IP_ADDRESS:NUMBER (Does NOT have to match PE-PE)
  • Route Target (extended community): IP_ADDRESS:NUMBER or AS:NUMBER (Export and Import MUST match PE-PE)
  • Interface towards CE to be allocated to VRF

NOTES:

In production, disable TTL propagation (on ALL MPLS routers) to hide label info inside traceroute! (no mpls ip propagate-ttl)

Configuration (On PE routers):

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vrf definition 100:THECOMPANY
  rd 100:1
  address-family ipv4
    route-target export x.x.x.x:100 (reversed on other PE router)
    route-target import y.y.y.y:100 (reversed on other PE router)
    exit
  exit

interface Gi0/1
  description THECOMPANY
  vrf forwarding 100:THECOMPANY (matches VRF definition)
  ip address x.x.x.x x.x.x.x (lives inside VRF)
  no shutdown

Verify:

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show ip interface brief
show vrf
show ip route vrf 100:THECOMPANY

Routing Between CE and PE:

  • Routing needs to be configured and associated to VRF (PE routers ONLY)
  • CE routing needs to be configured (CE routers ONLY)
  • Mutual redistribution IGP<—>mBGP needs to be configured (PE routers ONLY)

OSPF (PE):

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router ospf 100 vrf 100:YOURCOMPANY
  network x.x.x.x x.x.x.x area 0

show ip route vrf 100:YOURCOMPANY

OSPF (CE):

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router ospf 1
  network x.x.x.x x.x.x.x area 0

EIGRP (PE):

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router eigrp 1
  address-family ipv4 vrf 100:YOURCOMPANY autonomous-system 100
  network x.x.x.x

show ip route vrf 100:YOURCOMPANY

EIGRP (CE):

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router eigrp 1
  network x.x.x.x
  no auto-summary

RIP (PE):

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router rip
  version 2
  address-family ipv4 vrf 100:YOURCOMPANY
    network x.x.x.x
    no auto-summary

show ip route vrf 100:YOURCOMPANY

RIP (CE):

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router rip
  version 2
  network x.x.x.x
  no auto-summary

BGP (PE):

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router bgp 100
  address-family ipv4 vrf 100:YOURCOMPANY
    neighbor x.x.x.x remote-as 101 (eBGP)
    exit
  address-family ipv4
    neighbor x.x.x.x next-hop-self

clear ip bgp x.x.x.x
show ip route vrf 100:YOURCOMPANY

BGP (CE):

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router bgp 101
  neighbor x.x.x.x remote-as 100 (eBGP)
  network x.x.x.x

Redistribution on PE routers:

  • CE routes to be imported into VRF and exported to mBGP
  • VPNv4 labels will be added to Label Switched Path (LSP) (Bottom Label).
  • Route distinguiser (RD) and Route Target (RT) will be attached to routes.

OSPF mutual redistribution:

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router bgp 100
  address-family ipv4 vrf 100:YOURCOMPANY
    redistribute ospf 100 vrf 100:YOURCOMPANY
    exit
  exit

router ospf 100 vrf 100:YOURCOMPANY
  redistribute bgp 100 subnets

EIGRP mutual redistribution:

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router bgp 100
  address-family ipv4 vrf 100:YOURCOMPANY
    redistribute eigrp 1
    exit
  exit

router eigrp 1
  address-family ipv4 vrf 100:YOURCOMPANY autonomous-system 100
    redistribute bgp 100 metric y y y y y

RIP mutual redistribution:

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router bgp 100
  address-family ipv4 vrf 100:YOURCOMPANY
    redistribute rip
    exit
  exit

router rip
  address-family ipv4 vrf 100:YOURCOMPANY
    redistribute bgp 100 metric y (hop count)

Verify:

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show bgp vpnv4 unicast rd 100:1 labels
show bgp vpnv4 unicast vrf 100:YOURCOMPANY label
show mpls forwarding-table vrf 100:YOURCOMPANY
show ip cef vrf 100:YOURCOMPANY x.x.x.x/xx
show bgp vpnv4 unicast vrf 100:YOURCOMPANY x.x.x.x/xx
show ip protocols
traceroute x.x.x.x
traceroute mpls ipv4 x.x.x.x x.x.x.x

Using “VRF-aware” applications for troubleshooting:

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show ip route vrf 100:YOURCOMPANY
ip route vrf 100:YOURCOMPANY x.x.x.x y.y.y.y z.z.z.z
ping vrf 100:YOURCOMPANY x.x.x.x
traceroute vrf 100:YOURCOMPANY x.x.x.x
telnet x.x.x.x /vrf 100:YOURCOMPANY

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