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AdvancedPublished 2026-07-04

Lab 9: Dual-Stack IPv4/IPv6 Addressing on IOS

Bundle lab

Configure and verify dual-stack IPv4 and IPv6 addressing on Cisco IOS router interfaces. R1-R2 share a /30 IPv4 and /64 IPv6 point-to-point transit, while R1 provides a dual-stack user LAN gateway. No routing protocols or router static routes are permitted; verify only directly connected reachability.

Track
Est. time
45 minutes
Difficulty
Advanced
Topics

Learning objectives

  • Explain dual-stack operation and why both IPv4 and IPv6 can coexist on the same interface
  • Configure IPv4 addresses with dotted-decimal masks and IPv6 global unicast addresses with /64 on IOS
  • Enable IPv6 forwarding with ipv6 unicast-routing
  • Bring interfaces up and verify addressing using show ip interface brief and show ipv6 interface brief
  • Validate directly connected IPv4 and IPv6 reachability without any routing protocols or router static routes

Troubleshooting focus

  • Interface is administratively down: ensure no shutdown on each addressed interface
  • IPv6 not forwarding: ensure ipv6 unicast-routing is enabled on each router
  • Mask/prefix mismatch on a point-to-point: verify 255.255.255.252 for the /30 and /64 on both ends
  • Typos in addresses cause duplicate or out-of-subnet IPs: check exact values and neighbor IPs
  • Host default gateway wrong: confirm 192.168.100.1 and 2001:db8:100::1 on clients

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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