AdvancedPublished 2026-10-10

CCNP VRF & GRE: Routing Over the Tunnel

Archive lab

The tunnel works, but static routes won't scale. Run OSPF across it, and size its packets so nothing gets dropped.

Track

CCNP

Est. time

45 minutes

Difficulty

Advanced

Topics

CCNP, GRE, OSPF, MTU

Learning objectives

The neighbor never reaches FULL: compare the MTU on both tunnel ends
The tunnel flaps once OSPF is up: the far end's public address must not be learned through the tunnel

Subscribe to preview this lab's topology.

How this lab is graded

Build it your way. Where a lab lets you choose a value — a VLAN name, an interface description — grading checks that you configured it, not which name you picked. Names that another line has to reference, like an ACL applied with access-class, are stated in the guide and do have to match.
Addresses, modes and protocol keywords are exact. An IP address, a subnet mask, switchport mode trunk, an encapsulation — these carry the meaning of the lab, so they are graded as written in the guide.
Grading reads your saved configuration. Export the lab from CML after you have configured it, and make sure anything you set is in the running-config — a change that only exists in a terminal session never reaches the grader.
You can submit as many times as you like. Your best score stands, and each attempt tells you which checks passed so you can work the gaps.
Scored something you believe is correct? Use Report an issue on this page — that is exactly how the grading fixes in the changelog got found.

Create a free account to submit your lab for grading.

Found a problem with this lab?

Please sign in to report a problem — tying it to your attempts lets us reproduce and fix it faster.