[ppml] Proposed Policy: PI assignments for V6

marcelo bagnulo braun marcelo at it.uc3m.es
Thu Dec 9 10:42:03 EST 2004

Hi Stephen,

just a  comment...

El 09/12/2004, a las 1:15, Stephen Sprunk escribió:
>> That said. There are a few things I think is being forgotten in this 
>> discussion, and I really, really didn't want to point this out, but I 
>> guess I have to. PI space have the property that you can take it with 
>> you when you change providers, and really only solves renumbering. It 
>> does not give you anything wrt provider independence you do not 
>> already have. Why? Because you can today already either get multiple 
>> PAs, which won't help the problem with surviving TCP flows, but 
>> honestly, PI won't help you with that either.
> Please explain how connections using PI addresses do not survive when 
> a site's link to the respective provider goes down, either 
> intentionally or otherwise.

i don't know what Kurtis had in mind when he made this comments, if you 
pretend to obtain tcp connection survivability with current size of the 
bgp global routing table, you will find the probelms described in C. 
Labovitz, A. Ahuja, A. Bose, “Delayed Internet Routing Convergence”, 
2000, SIGCOMM 2000.

in addition you probably have to deal with default BGP keepalive timer 
which in widely deployed commercial routers is 180 seconds. This means 
that some failures modes that are only detected through bgp keepalives, 
it will take 3 minutes to detect the failre which is probably longer 
that most apps using tcp connections are willing to wait. So the 
question is how much of this feature of established connection 
preservation through BGP reconvergence is actually a myth (in ipv4)... 
(clearly for now in ipv6 i guess we don't have delayed reconvergence, 
for now)

regards, marcelo

>> The multiple PAs help with migration. So, why else do you want PA 
>> space, redundancy? Sure, as an end-site you will today get a /48. 
>> There is nothing in the world to prevent you from advertising your 
>> /48 to several upstreams, except filtering by the upstreams. Will PI 
>> space help you there? Not if the PI space is /48....
> If there is a PI block with a minimum assignment/allocation of /48, 
> then presumably providers will relax their filters for that block.  
> This has been the case when RIRs have changed allocation policies for 
> IPv4.  There is strong historical record to show that most will NOT 
> accept a route longer than the minimum allocation size in a particular 
> block.
> S
> Stephen Sprunk         "God does not play dice."  --Albert Einstein
> CCIE #3723         "God is an inveterate gambler, and He throws the
> K5SSS        dice at every possible opportunity." --Stephen Hawking

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