[address-policy-wg] Re: Assignments for Critical Infrastruction

2008/10/29 Marco Hogewoning <marcoh at marcoh.net>:
>
> On Oct 29, 2008, at 9:10 AM, Stephane Bortzmeyer wrote:
>
>> On Tue, Oct 28, 2008 at 11:48:06AM +0100,
>> Ond??ej Surý <ondrej.sury at nic.cz> wrote
>> a message of 9 lines which said:
>>
>>> We would like to see policy for IPv4 and IPv6 modifiedto allow /24
>>> *minimum* for IPv4 and /48 *minimum* togTLD/ccTLD.  First reason
>>> behind this is that one PI is not reallyenough and it's blocking us
>>> to deploy more DNS serversand make our TLD service more reliable.
>>
>> As a TLD, I agree. ".fr" has currently two anycast nodes (managed
>> outside, so they do not use "our" addresses) and plan to add more and
>> to manage them ourselves. We will therefore need more than one PI prefix.
>
> Maybe I understand, maybe I don't...but isn't the whole idea of anycast that
> you create redundancy by adding more machines/locations in the same address
> space ? So what exactly are you trying to gain by adding multiple anycast
> blocks, that's not exactly clear with me.

We discussed this face to face, but just for the record.  Idea of having
multiple PI anycast clouds is to have:

M servers in N anycast clouds and L locations and each anycast cloud includes
K servers, where L >= N, M >= L and K << M

Picture would be better here :(.

Very simple example in plain words: each anycast cloud will
have 3 servers placed in 3 different location, and each two
anycast clouds can share no more then 2 locations with another
anycast cloud.  Each location cannot hold more then two anycast
clouds.

Anycast clouds: A1 A2 A3 A4
Locations: L1 L2 L3 L4 L5 L6

A1(L1 L2 L3)
A2(L1 L4 L5)
A3(L2 L4 L6)
A4(L3 L5 L6)

That way any two locations can fail without failure of any
anycast node.

Ondrej.
-- 
 Ondřej Surý
 technický ředitel/Chief Technical Officer
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