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BeginnerPublished 2026-06-29

Static Routing Between Branches Through an HQ Hop

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Deploy IP addressing and bidirectional static routing across a three-router topology to connect two branch LANs through an HQ hop. Practice verification from end hosts, analyze routing tables, and troubleshoot asymmetric reachability.

Track
Est. time
45 minutes
Difficulty
Beginner
Topics

Learning objectives

  • Assign and verify correct interface IP addresses and subnet masks on routers and hosts.
  • Configure static routes that provide end-to-end LAN connectivity across multiple hops.
  • Explain and demonstrate why routing must be bidirectional for return traffic to succeed.
  • Verify forwarding decisions with routing tables and traceroute.
  • Troubleshoot one-way reachability caused by missing or incorrect static routes.

Troubleshooting focus

  • SITE-A-HOST pings 10.20.20.10 but SITE-B-HOST cannot ping 10.10.10.10: the return path is missing.
  • Pings still fail although the static routes are configured: check the next hop. It must be the directly connected neighbour's interface, never your own local IP.
  • ARP and routing anomalies on a LAN: a mask mismatch. A /24 configured as /25 or /23 misbehaves — verify masks on both router LAN interfaces and on the hosts.
  • traceroute -n 10.20.20.10 stops at the last working router: the transit interface past that hop is down. Verify interface status and cabling.
  • A host reaches its own gateway but nothing beyond it: SITE-A-HOST must use 10.10.10.1 and SITE-B-HOST 10.20.20.1 as default gateway.

Topology

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Grade your work

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.

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