What is my IPv6 ASN?

Your IPv6 ASN

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More about your connection

ASNs and IPv6 routing

The displayed ASN (autonomous system number) identifies the network that announces your IPv6 address to the internet. In most cases it is the same network as your IPv4 ASN, the one run by your ISP.

One ASN, two protocols

An autonomous system is a network with its own routing policy, identified by a number such as AS3320. ASNs don’t belong to a protocol: the same number announces both the network’s IPv4 ranges and its IPv6 ranges using BGP (with its multiprotocol extensions for IPv6).

Why IPv6 routes can differ

Even with the same ASN, IPv6 and IPv4 traffic can take different paths across the internet. Not every network peers over both protocols, so IPv6 packets sometimes cross extra networks or take a longer route, though that gap has largely closed between major networks.

When your IPv6 ASN differs from IPv4

  • Tunnel brokers: IPv6 tunnels appear under the tunnel provider’s ASN, for example Hurricane Electric’s AS6939.
  • VPNs: a VPN with IPv6 support shows its hosting provider’s ASN. If your home ISP’s ASN appears while the VPN is on, see the IPv6 leak check.
  • Separate operators: some ISP groups run IPv6 through a different subsidiary network.

Frequently asked questions

Is my IPv6 ASN the same as my IPv4 ASN?

Usually, yes. One autonomous system can announce both IPv4 and IPv6 ranges. A different ASN means your IPv6 traffic arrives through another network, such as a tunnel broker or a VPN.

Do ASNs work differently for IPv6?

No. ASNs are protocol-independent. The same number identifies the network for both IPv4 and IPv6, and both use BGP to exchange routes.

How can I see which IPv6 ranges an ASN announces?

Public routing tools such as bgp.he.net and RIPEstat list every IPv4 and IPv6 prefix an ASN announces, along with its peers.