[address-policy-wg] Policies interact

On Thu, 07 Apr 2005 11:58:15 +0200, Wilfried Woeber, UniVie/ACOnet wrote:
>  For a routing decision you don't need 32 bits for an IPv4 prefix,
>  and you do not need 128 bits for an IPv6 prefix.
Exact.
A international routing decision can be limited to the first 64 Bits.
The remaining 64 Bits are some sort of ARP-replacement.

>  My wild guess would be that the ratio is rather on the order of
>  1:1.5 than 1:4.
It can be 1:1 (TCAM or sparse tries) for good implementations
up to 1:4 or even worse for poor implementations.

*Of course* the IPv4 approach with 32 bits has clear advantages
regarding real world implementations and a worlwide unique 32 bit
address is a reasonable choice.

Thus IPv6 makes only sense if:
- the remaining address part can be used and internationally routed
- there is a clear advantage for using larger addresses
- none of these is restricted as it currently is (200 customers rule, no PI)
- all important IPv4 features are available with IPv6

Face it:

Either IPv6 can be used with its full advantages, which means
- full and true routing support for the first 64 bits
- Multihoming, PI, reasonable global table processing

which imposes:
- using state of the art routing hardware and yes, this means
  spending money, like it or not,
- removing unnecessary address assignment restrictions to gain
  the best results from the large address space,
  yes, this means trusting the engineers that they will be able
  to handle larger tables,

or IPv6 will die.

The market will not accept a IPv6 with address bits overhead
not usable for reasonable international connectivity.
The market then will stay with IPv4, which is a reasonable choice.

Greetings Oliver



Oliver Bartels F+E + Bartels System GmbH + 85435 Erding, Germany
oliver at bartels.de + http://www.bartels.de + Tel. +49-8122-9729-0