6to4 status (again)

[Mike Leber]

On 3/1/13 9:56 AM, Kevin Day wrote:
>
> On Mar 1, 2013, at 3:24 AM, Lorenzo Colitti <lorenzo at google.com 
> <mailto:lorenzo at google.com>> wrote:
>
>> On Fri, Mar 1, 2013 at 12:39 AM, David Farmer <farmer at umn.edu 
>> <mailto:farmer at umn.edu>> wrote:
>>
>>     So PLEASE just don't go turning off 6to4 relays willy-nilly,
>>     turning them off when there is no more traffic is fine.  But,
>>     just turning them off when there is traffic adds to bad user
>>     experience we are trying to correct.
>>
>>     If you need to manage the traffic to your relay then change your
>>     BGP advertizements to make it look less attractive, or change the
>>     scope of your advertizements to cover only your direct customers,
>>     but don't just turn it off.
>>
>>
>> Every time someone turns off a relay or limit the scope of the BGP 
>> advertisements they are reduce the total capacity of the system. The 
>> traffic doesn't disappear, it goes somewhere else, and with every 
>> relay it's more likely to be dropped. There's just no way to win this 
>> game.
>
> That's been my concern with shutting our relay down.
>
> http://bgp.he.net/net/192.88.99.0/24 shows 23 ASNs announcing 
> 192.88.99.0/24. I'm sure he.net <http://he.net>'s list isn't complete, 
> but I'm also guessing they're seeing some announcements that are 
> "peers only" so not all of those are public. For the sake of argument, 
> let's say there are 23 public relays in the world.

(I was going to stay out of this, since 6to4 is a migration technology 
that will gradually go away over time, and aside from making sure 
whatever one has bothered to setup is working correctly, we all have our 
normal business to attend to.)

This is an incorrect assumption of 1 relay per network.

If you are going to setup 6to4 and you are a network operator, then you 
should be prepared to run multiple anycast 6to4 servers on your network 
in geographically distributed locations.  I know multiple networks are 
doing this.  We are doing this as well.

If your 6to4 server is overloaded please stop publicly announcing it and 
use it just for your own return traffic.  Don't burden yourself with 
announcing your own resources for public use if you don't want to 
maintain or plan for that use.  There's nothing wrong with not wanting 
to do it.  So don't.  Run one for yourself if you want to. If you don't, 
don't.

IPv6 traffic is going to get big (obviously).  As it gets big, even some 
of these transition technologies will get big, even as they become a 
smaller percentage of the total traffic.  In one market we are seeing 
2.5 Gbps of 6to4 traffic to our relays.  Yes, this means that you need 
to be prepared to handle that if you want to publicly announce your 6to4 
servers.  Multiple servers and/or 10GE interfaces, etc.  The reason to 
run 6to4 servers is if you want to make sure that specific traffic 
within your control and responsibility is handled as well as you think 
it should or could be.  It's just one of many many things you can attend to.

Mike.
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