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GRE VPN Endpoint Migration

A site-to-site GRE tunnel has just moved to new ISP addresses. The tunnel comes up, but the two sites still can't reach each other's services. Find what the migration missed.

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The lab as it opens in PNETLab: two sites joined by a GRE tunnel across the ISP, after the move to new public IPs.

What you'll practise

  • Audit the two-site GRE topology and find the loopbacks that stand in for each site's services
  • Verify tunnel source and destination after the move to new ISP IPs
  • Re-establish the routing adjacency that runs across the tunnel
  • Verify overlay route propagation and tunnel MTU
  • Confirm cross-site reachability between the service loopbacks after cutover

Set it up

  1. 1

    Have the node image ready

    Images are not included. The file expects your own licensed copy of:

    • L3-ADVENTERPRISEK9-M-15.4-2T.bin

    If your copy has a different name, open each node's Edit dialog after importing and pick your image from the list.

  2. 2

    Copy it to the server and fix permissions

    Replace <your-server> with the IP address or hostname of your EVE-NG or PNETLab server.

    $ scp gre-vpn-endpoint-migration-lab.unl root@<your-server>:/opt/unetlab/labs/
# then, logged in to the server:
$ /opt/unetlab/wrappers/unl_wrapper -a fixpermissions
  3. 3

    Open it and start the nodes

    The canvas notes list the objectives, and the workbook walks through the fix.

Free to use and share under CC BY 4.0. Please credit LabFabric with a link to this page.