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Using IPv6 for multihome ISP eBGP peering due to IPv4 public /24s no longer available

Last updated on January 4, 2019

  • Problem:
  • I have two routers, and two separate ISPs (two different public ASNs). I wish to accept full BGP routes in order for us to properly set up true reliable ISP failover in a way that allows both links to be utilized. From my understanding, the only truly effective/reliable way of doing this is by accepting full routes and advertising my public ASN to the internet. The problem here is that obtaining a public /24 IPv4 block of addresses is not possible due to cost/lack of IPv4 public address space. Additionally, the LAN/intranet network must remain IPv4 on the "backend".
    • My question is:
    Is it possible to leverage the untapped IPv6 public IP address space and use that in lieu of a public /24 IPv4 block in order to advertise our public ASN out multiple providers (and therefore, provide the flexibility and control needed in order to manage those multihomed connections)? The key here is that IPv6 would ONLY be used to allow us to accept full routes and advertise our public ASN across both providers. The backend (literally the entire LAN/intranet) would have to run strictly on IPv4. Is this even possible? If so, what are the limitations? -- Follow-up question: How do people in modern times (i.e. mid 2010s) tackle this multihoming problem when they are unable to obtain a /24 public IPv4 block? For more clarity, the ultimate goal is the ability to utilize both ISPs at the same time for every day traffic flow to the point where if a current video conferencing session over one ISP was to fail, it would automatically re-route and continue working over the other ISP.
    Edit: Note: For the sake of this question, it is not possible to a) use IPv6 on the LAN/Intranet side instead of IPv4 and b) Somehow obtain a /24 public IPv4 block by purchasing it from a third party.

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