Re: [Casm] New Version Notification for draft-xie-ps-centralized-address-management-02.txt

Brian E Carpenter <brian.e.carpenter@gmail.com> Wed, 22 March 2017 13:47 UTC

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To: MarcoH - lists <mchlist@xs4all.nl>, casm@ietf.org
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From: Brian E Carpenter <brian.e.carpenter@gmail.com>
Organization: University of Auckland
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Date: Thu, 23 Mar 2017 02:46:52 +1300
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Subject: Re: [Casm] New Version Notification for draft-xie-ps-centralized-address-management-02.txt
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On 22/03/2017 20:58, MarcoH - lists wrote:
>> Hi,
>>
>> This draft makes a strong case for coordinated address management.
>> In my opinion, it makes no case at all for *centralized* address
>> management. But apart from that one word to change, I think it's
>> very good.
>>
>> Regards
>>   Brian Carpenter
> 
> Tend to agree here, while I can see how the word “centralised” came in, we might be better off if this project would use the term “coordinated” address management where possible.
> 
> Further in response to the draft, Section 5 “requirements” in the second 2nd bullet reads:
> 
> "A fast return of unused resources for reassignment is of high value.”
> 
> While I can see this as a value for scarce resources such as IPv4 addresses or IP port ranges, I am not sure if this is a beneficial property for IPv6, where networks should be able to afford themselves the luxury of providing hosts with a stable address (prefix) when they require it.

Yes, policy details will be different for IPv6. For example, I believe that some registries (manually) over-allocate IPv6 requests so that a later request for more space can be allocated contiguously. But the principle that free resources can be made available immediately is important. In a distributed solution that is easy; the resource does not need to be "returned", it is simply available when a peer asks for it.

> 
> For now I can probably live with the terminology used, but would like to see some clarification on how this requirement will be further expanded and refined to allow for more stable or predictable IPv6 prefixes, without the need to go full static (which would remove a lot of the benefits in efficiency).

Policy of this kind should be configurable, IMHO.

    Brian