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Re: v4 exhaustion and v6 impact [Re: cost of dual-stack vs v6-only]

  • From: Pekka Savola
  • Date: Thu Mar 13 13:57:04 2008

On Thu, 13 Mar 2008, Owen DeLong wrote:
While the goal may be good, a reality check might be in order. AFAICS, the impact will be that residential and similar usage will be more heavily NATted. Enterprises need to pay higher cost per public v4 address. IPv4 multihoming practises will evolve (e.g., instead of multihoming with PI, you multihome with one provider's PA space; you use multiconnecting to one ISP instead of multihoming). Newcomers to market (whether ISPs or those sites which wish to start multihoming) are facing higher costs (the latter of which is also a good thing). Obviously DFZ deaggregation will increase but we still don't end up routing /32's globally.

I am confused by your statement. It appears you are saying that it is a good thing for sites that wish to multihome to face higher costs. If that is truly what you are saying, then, I must strenuously disagree. I think that increased cost for resilient networking is a very bad thing.

I understand your reasoning (we've been through this before so we'll just have to agree to disagree). If a site is unwilling to pay, e.g., 10000$/yr for its multihoming, maybe it should stop polluting the global routing table and instead use other redundancy mechanisms. Today, it's too cheap to pollute global DFZ; increasing the cost motivates finding other mechanisms to obtain redundancy.

While price for a /20 or /16 of address space might go up pretty high, a /24 can still be obtained with a reasonable cost. Those ISPs with lots of spare or freeable v4 space will be best placed to profit from new customers and as a result v6 will remain an unattractive choice for end-users.

Only for some limited period of time.  Even those "freeable" /24s will get
used up fairly quickly.

Even a single /8 will allow 64K allocations for multihoming perspective; that's more than we have today, and there is a lot more spare or freeable space to use.

However, once we reach somewhat minimal critical mass in IPv6 content, and, NAT-PT solutions are more readily available and better understood, I think you'll see most new enterprise deployments being done with IPv6.

I agree with most of what you're saying but given that most enterprise admins are familiar with v4 and not with v6, if the enterprise is going to be completely behind a NAT or NAT-PT anyway, it may be difficult to find the benefit to deploy the enterprise network with v6 rather than with v4 private addresses. Easier company mergers is probably one of the highest on the list, "futureproofing the network" is probably not considered worth the expense.

So v6 capabilities in the ISP backbones will improve but the end-users and sites still don't get v6 ubiquituously. This is a significant improvement from v6 perspective but is still not enough to get to 90% global v6 deployment.

I'm not sure why 90% is necessary or even desirable in the short
term.  What's magic about 90%?

Don't ask me for the magic number -- I just took what Leo offered. :-)

What I think is more interesting is arriving at the point where you can deploy a new site entirely with IPv6 without concerns about being disconnected from some (significant) portion of the internet (intarweb?).

I agree that's an interesting (earlier) scenario. To me what you require represents a situation where basically every ISP is offering v6 and it's widely considered to have similar SLAs as v4 today has, and it's used sufficiently widely and is reliable.

To get there in practice, ISPs will need users which require this kind of SLAs and reliability. So, while 90% user and content penetration is is not needed to reach this goal, it will need to be significantly higher than, say, 5%. Who are going to be the first v6 end-sites and content provides? It's a thankless job to be on the bleeding edge and it may be difficult to define a business case for it.

Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings