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MPLS and L3VPN lab 8 of 11

Internet access from a VRF: route leaking and NAT

Give a VPN customer Internet access through one PE. Leak a default out of the VRF and a public block back in, send the default through the VPN, then add VRF-aware NAT for offices on private addresses, including the remote one whose traffic arrives in MPLS.

Run this lab

It needs Lite: its 6 nodes are set to 6 vCPU and 3,072 MB in total. That fits the free demo too.

In your workspace: Shared, then MPLS and L3VPN guided labs, then 08 - Internet access from a VRF - route leaking and NAT

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Level
Advanced
Time
About 75 minutes
Nodes need
6 vCPU, 3,072 MB
Smallest plan
Lite

The scenario

Alder Foods has two offices in a Wrenfield L3VPN, and it wants Internet access through the VPN rather than a second circuit at each office. PE1 has Wrenfield's Internet uplink to the upstream provider, router UP, in the global table. The test site on the Internet is 198.51.100.1.

Alder has two kinds of address, and they need different treatment:

AddressesWhereWhat it needs
192.168.1.0/24, 192.168.2.0/24Office LANsPrivate, so NAT on PE1, to the uplink's address 203.0.113.2
203.0.113.64/29Public server block on CE1Public, so plain routing, no NAT

The upstream runs an anti-spoofing filter, FROM-WRENFIELD, on its link to you. It drops any packet with a 192.168.x.x source, so a NAT mistake can't hide: its counters show what really arrived.

DeviceInterfaceAddressConnects to
CE1Loopback1192.168.1.1/24
CE1Gi0/0172.16.1.2/30PE1 Gi0/0
CE1Loopback2203.0.113.65/29
PE1Loopback010.255.0.1/32
PE1Gi0/0172.16.1.1/30CE1 Gi0/0
PE1Gi0/110.0.12.1/30P Gi0/0
PE1Gi0/3203.0.113.2/30UP Gi0/0
PLoopback010.255.0.2/32
PGi0/010.0.12.2/30PE1 Gi0/1
PGi0/110.0.23.1/30PE2 Gi0/1
PE2Loopback010.255.0.3/32
PE2Gi0/0172.16.2.1/30CE2 Gi0/0
PE2Gi0/110.0.23.2/30P Gi0/1
CE2Loopback1192.168.2.1/24
CE2Gi0/0172.16.2.2/30PE2 Gi0/0
UPLoopback1198.51.100.1/24
UPGi0/0203.0.113.1/30PE1 Gi0/3

What you’ll practise

  • Leak routes both ways between a VRF and the global table with static routes
  • Carry a default route through a VPN
  • Configure VRF-aware NAT on a PE
  • Work out which interface is NAT inside for traffic arriving from the MPLS core
  • Use the upstream filter counters to prove what really left the network

The tasks

  1. See the problem
  2. Leak in both directions
  3. Send the default through the VPN
  4. NAT for the local office
  5. NAT for the remote office

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of Internet access from a VRF - route leaking and NAT6 nodes, 5 links. Every link is listed as text below the diagram.CE1PE1PPE2CE2UPGi0/3Gi0/0Gi0/1Gi0/0Gi0/1Gi0/1Gi0/0Gi0/0Gi0/0Gi0/0
6 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • CE1 Gi0/0 to PE1 Gi0/0
  • PE1 Gi0/1 to P Gi0/0
  • P Gi0/1 to PE2 Gi0/1
  • PE2 Gi0/0 to CE2 Gi0/0
  • PE1 Gi0/3 to UP Gi0/0
Nodes in Internet access from a VRF: route leaking and NAT, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
CE1Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
PE1Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
PCisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
PE2Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
CE2Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
UPCisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder MPLS and L3VPN guided labs.

  3. Open 08 - Internet access from a VRF - route leaking and NAT and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Cisco, Juniper Networks and MikroTik. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.