North American Network Operators Group

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Re: design of a real routing v. endpoint id seperation

  • From: Michael.Dillon
  • Date: Mon Oct 24 05:44:53 2005

> The way around it is to stop growing the DFZ routing table by the size
> of the Prefixes.  If customers could have PI addreses and the DFZ
> routing table was based, instead, on ASNs in such a way that customers
> could use their upstream's ASNs and not need their own, then, provider
> switch would be a change to the PI->ASN mapping and not affect the
> DFZ table at all.

One way to do this is for two ISPs to band together
in order that each ISP can sell half of a joint
multihoming service. Each ISP would set aside a
subset of their IP address space to be used by many
such multihomed customers. Each ISP would announce 
the subset from their neighbor's space which means
that there would be two new DFZ prefixes to cover
many multihomed customers. 

Each multihomed customer would run BGP using a private
AS number selected from a joint numbering plan. This
facilitates failover if one circuit goes down but
doesn't consume unneccesary public resources per customer.

This does require the two ISPs to maintain a strict
SLA on their interconnects in order to match the SLAs
on their customer contracts. The interconnect then
becomes more than "just" a peering connection, it also
becomes a mission critical service component.

Of course, the whole thing multihoming thing could
be outsourced to a 3rd party Internet exchange
operator with some creativity at both the technical
level and the business level. The IP address aggregate
would then belong to the exchange. More than 2 ISPs could
participate. Customers could move from one ISP to another
without changing addresses. The SLA on interconnects could
be managed by the exchange. Etc.

--Michael Dillon