Re: BCP for multisite multihoming

[Gert Doering <gert@space.net>]

Hi,

On Mon, May 21, 2007 at 03:26:20PM -0500, Kevin Day wrote:
> Okay, if that's the approach you recommend, then sure. But:
> 
> Having an entire /32 per POP is tremendous overkill. And, it's still  
> using just as many routes as if this company could just deaggregate  
> the prefix it received. I'm also assuming that additional prefixes  
> aren't going to be free, which is going to further add to the  
> operating expenses of v6 over v4. It also means the company isn't  
> able to tailor its space usage to each POP.
> 
> Is one allocation/assignment per site really scalable?

Regarding address space usage, yes.  (Because a /32 more or less does
not really make any difference anywhere.  Even burning a million /32s 
isn't going to bring us anywhere near *address space* shortage issues.
[OK, come flame me.  *I* can do maths.  Can you?]).

Regarding routing table: it doesn't make a difference what you do 
("own /32, deaggregated single /32, PI networks") - with current 
routing technology, you end up with one routing table slot per location.
Which is not perfect, but as long as it stays at *one* prefix per 
location, it's still better than most IPv4 setups that outgrow their
initial prefix over time, and need to add more prefixes later on.

So - in the current policy and routing framework, my answer would be:

 - if this is ISP-like business, go for a /32 for each location, and 
   happily assign from that to the local customers

 - if this is a "enterprise-like" business, go for a /48 PI for each
   location [which might not be possible in each region]

 - if this is in between (datacenter, etc.), chose what model fits best


If the local policies do not permit multiple /32s for a "single enterprise",
either work on changing the policies (similar to the ARIN IPv4 policy about
disconnected networks being entitled to multiple allocations) or have each
local organization become a RIR member ("LIR" in RIPE land) of its own.

Gert Doering
        -- NetMaster
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