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IPv6 over IPv4

Tunneling enables IPv6 and IPv4 networks to coexist during the transition between protocol versions by encapsulating one protocol's traffic inside the other. This allows organizations to maintain connectivity across infrastructure segments that don't yet support a common IP version.

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About this video

Tunneling addresses one of the core practical challenges in migrating from IPv4 to IPv6: the fact that not all parts of a network path will complete the transition at the same time. By encapsulating packets from one protocol version inside the other, organizations can maintain end-to-end connectivity even when intermediate infrastructure doesn't share the same IP version. In the most common scenario, an organization has deployed IPv6 across its internal infrastructure but must send traffic through an ISP that only supports IPv4. At the network boundary, IPv6 packets are encapsulated inside IPv4 headers, transported across the provider's network, and then decapsulated and delivered as IPv6 on the far side. The internal hosts on both ends communicate using IPv6 throughout, with no awareness of the IPv4 segment in between. The reverse is also possible. If an ISP requires all traffic traversing its network to use IPv6 — but some internal systems or applications are still generating IPv4 traffic — that IPv4 traffic can be encapsulated inside IPv6 packets for transport across the provider's network, then unwrapped upon arrival. This bidirectional flexibility makes IP tunneling a practical tool for organizations at any stage of the IPv4-to-IPv6 migration.

What you'll learn

What's covered

IPv4 to IPv6 Tunneling

Aligned to

Cisco CCNA
1.9 Describe IPv6 address types
1.8 Configure and verify IPv6 addressing and prefix

Key terms

Encapsulation
The process of wrapping data with protocol headers as it passes down the layers of the OSI model.
Tunneling
A transition mechanism that encapsulates IPv6 packets within IPv4 headers (or vice versa) to carry traffic across a network that uses a different IP version.
Internet Protocol
IP
The principal communications protocol for routing packets across network boundaries.
Packet
A unit of data formatted for transmission over a network, containing a header, payload, and sometimes a trailer.

Transcript

One thing that tunneling is allowing us to do is make an easier transition from IP version 4 to IP version 6.

Tunneling IP version 6 over IP version 4

Let's say we're ready to roll out IP version 6 and we have applications that need to run IP version 6. So we're all ready to set up IP version 6, and we have that on all of our networks within our infrastructure. However, maybe we're going across an internet service provider that doesn't provide full IP version 6 capability — maybe they're only providing IP version 4. In this case right here, maybe we need to tunnel IP version 6 over IP version 4.

So what that would look like is all of the machines within this network would have IP version 6, but then when it gets to this router right here, it gets tunneled across this network with IP version 4, and then unpacked on this side and delivered with IP version 6 again.

The reverse

We can also do the reverse. Let's say our internet service provider is mandating that everything that communicates across their network is using IP version 6, and maybe some of our traffic is still using IP version 4. So what we can do is we can encapsulate this IP version 4 with the IP version 6 to go across their network, and then send it into our other side.

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