Cost of operating v4/v6 combined for some time includes, among other things:

1. Help Desk calls resulting from confused customers wanting configuration help.
2. Memory for Routing Information for IPv4 plus IPv6.
3. Help Desk calls resulting from errors by confused engineers trying to work both protocols on too many devices.
4. Cost of documentation and training for Help Desk personnel.
5. Cost of "Linksys WRT54G-IP6" or equivalent because of increased memory and programming requirements.
6. Cost of software maintenance for network core router software -- didn't we just go through getting rid of DECnet, SNA, IPX/SPX, and AppleTalk because of this, among other reasons??
7. Marketing cost of being perceived as "obsolete".
8. Opportunity cost due to more complex delivery configurations slowing down sales.
9. Cost of "IP Naming and Addressing Management" due to multiple protocol complexity -- didn't we just go through getting rid of DECnet, SNA, IPX/SPX, and AppleTalk because of this, among other reasons??

Of course, this is just a smattering. Note also that, although hardware costs for the router core are driven primarily by speed and port count, memory costs can be substantial.

At 7/24/2007 11:50 AM -0400, Chad Oleary wrote:
<snip/>
However, what I'm trying to understand is why the motivation to
rapidly go from v4 to v6 only? What are the factors I'm missing in
operating v4/v6 combined for some time?

Chad

-
James R. Cutler
james.cutler@consultant.com