North American Network Operators Group
Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: IPv6 vs IPv4 (Re: Sprint NOC? Are you awake now?)

  • From: Iljitsch van Beijnum
  • Date: Wed Sep 03 04:46:10 2003 
On dinsdag, sep 2, 2003, at 23:18 Europe/Amsterdam, Nenad Pudar wrote:
Again my point is that your site (or any other that use the same dns for ipv4 and 6) may be "blackholed" by ipv6 (it is not the question primary about the quality ipv6 connction it is the fact that your ipv4 connection which may be excelant is blackholed with your ipv6 connection which may not be good and to me the most obvious solution is not to use the same dns name for both)
First of all, why are you repeating everything the previous posters said? This is a waste of bandwidth. Not only on the network, but also where it really matters: in the synapses.

The real problem is that your software assumes that if there are several addresses in the DNS, it can just pick one and assume that address works. That has never been a good idea, but in IPv4 you can get away with it. In IPv6, you can't. IPv6 hosts are required to support more than a single address per interface, and when people actually use this then it's only a matter of time before address #1 becomes unreachable while address #2 is still reachable. So this means you have to try them all.

The new name to address mechanisms for IPv6 are such that you can ask for IPv4 addresses, IPv6 addresses or both for a certain FQDN. If you choose both, you'll usually get an IPv6 address first.

I don't see how it would be reasonable to have separate FQDNs for all these addresses and have the user try them all rather than simply have the application walk through the list of addresses and try them all until it gets a live one.

(And yes, I've suffered from decreased performance because of non-optimal or even nonexisting IPv6 connectivity, but that's the price of being an early adapter.)

Now if your argument is that it's not a good idea to depend on applications handling this they way they should _today_ that is something I'm willing to discuss, although I don't necessarily agree.

BTW, my IPv6 connectivity for www.bgpexpert.com is in some ways better than IPv4 as there is an extra path available over IPv6 that isn't available over IPv4.