🌐

IPv6 Dual-Stack Configuration

Jun 12, 2025

Overview

This lecture covers hands-on IPv6 address configuration in a dual-stack network, emphasizing the key steps for adding IPv6 alongside IPv4 and important differences between the two protocols.

Dual-Stack IPv6 Configuration Lab

  • IPv4 is already running; IPv6 is added without removing IPv4, creating a dual-stack setup.
  • Enable IPv6 routing on the router using the ipv6 unicast-routing command (not enabled by default).
  • Configure IPv6 addresses on R1 interfaces using ipv6 address <address>/<prefix>.
    • G0/0: 2001:DB8:0:1::1/64
    • G0/1: 2001:DB8:0:2::1/64
    • G0/2: 2001:DB8:0:3::1/64
  • Set each PC's IPv6 address and default gateway to match R1's corresponding interface.
  • Verify configuration with show ipv6 interface brief, noting auto-configured link-local addresses.
  • Pings between PCs on different subnets fail until ipv6 unicast-routing is enabled.

Boson NetSim Lab Tasks & Concepts

  • Confirm existing IPv4 addresses on routers match network documentation.
  • IPv4 is the current addressing, with a maximum of over 4 billion unique addresses.
  • Insufficient IPv4 addresses drive the need for IPv6 adoption.
  • IPv6 provides a theoretical maximum of 3.4 × 10³⁸ addresses, addressing future scalability.
  • IPv6 addresses are 128 bits, compared to IPv4’s 32 bits.
  • Dual-stack allows IPv4 and IPv6 to coexist during the transition phase.
  • Enable IPv6 forwarding on routers (ipv6 unicast-routing); configure appropriate IPv6 addresses on interfaces.
  • Verify IPv6 connectivity with pings after configuration.

Key Terms & Definitions

  • Dual-Stack — Running IPv4 and IPv6 simultaneously on network devices for migration.
  • IPv6 Unicast Routing — Router feature enabling forwarding of IPv6 packets.
  • Link-local Address — An IPv6 address auto-configured for local link communication, not routable.
  • Prefix Length — Number of leading bits in the address defining the network portion (/64 common in IPv6).

Action Items / Next Steps

  • Practice IPv6 interface configuration and router setup in Packet Tracer or NetSim.
  • Review the differences between IPv4 and IPv6 address structure and capabilities.
  • Complete lab assignments: enable ipv6 unicast-routing, assign IPv6 addresses, test with pings.

Full transcript