[ppml] IPv6, Vista, and the Popular Press

Stephen Sprunk stephen at sprunk.org
Fri Jun 8 21:35:41 EDT 2007

Thus spake "Sean Reifschneider" <jafo at tummy.com>
> On Sat, Jun 09, 2007 at 12:48:21AM +0000, Paul Vixie wrote:
>>than 32 bits to be worth the cost of transition, and enough bits
>>that we'd never run out, but still small enough to build with
>> 1990's hardware.  the
> Why have I heard so much about routers not being able to handle
> IPv6?  Is it really not as big a problem as I've heard (I honestly
> don't know), or was the "can be built with '90s hardware" believe
> a bit optimistic?

[ Putting on my vendor hat for a moment... ]

Vendors build what they think* customers will buy.  It was _possible_ to 
build an IPv6 router with 1990s hardware, but like any feature, implementing 
it adds expense and thus either increases prices or reduces profits.

Many hardware routers/linecards were thus designed without hardware to 
forward IPv6 packets based on the belief (probably true at the time) that 
customers would not be willing to pay the increased prices necessary to 
build IPv6-capable devices at "acceptable" profit levels.  The result is 
that many core routers out there can only forward IPv6 in software -- at ~1% 
of their hardware-based forwarding rate for IPv4.  Non-trivial levels of 
IPv6 traffic scare folks who bought those devices.

Software is a somewhat similar matter: do you spend your limited developer 
budget on writing new IPv4 features that people will throw money at you for, 
or do you code an IPv6 stack that will go mostly unnoticed?  It's gradually 
gotten done over time at most vendors, and the major difference is that 
software can be back-ported to existing routers at little per-unit cost, but 
it's still woefully lacking in CPE devices (Apple's one model aside).


* Some vendors are better than others at guessing what customers will spend 
money on, and that guessing is an art, not science.  In particular, asking 
your customers what they'd like to see is notoriously unreliable because 
they'll ask for lots of things that won't actually influence their buying 
decisions.  It takes customers threatening to take their business elsewhere 
for demand to be believed.

Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov 

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