[arin-ppml] Draft Policy ARIN-2012-7: Reassignments for Third Party Internet Access (TPIA) over Cable

Jean-Francois.TremblayING at videotron.com Jean-Francois.TremblayING at videotron.com
Thu Sep 6 15:27:54 EDT 2012

arin-ppml-bounces at arin.net a écrit sur 06/09/2012 02:01:03 PM :

> Joe Maimon <jmaimon at chl.com> 
> Does the technology inherently require this sort of unaccountability and 

> is there any way to change that and is it worth accommodating and 

As someone familiar with this environment, let me try to shed some light 
the issue. I'm afraid it's not a short and simple explanation. 

Canadian cable operators do indeed require third parties to provision all 
the access equipment (CTMSes) in a given "region" with subnets roughly 
in size to the largest number of clients on any equipment. The reason 
this is quite simple, the third party does not have a vision of which 
equipment correspond to the street address of a specific potential client. 

By the nature of the cable technology, such street address <-> equipement 
relationship changes in the network almost on a daily basis. The IP 
provisioning must therefore be blanketed across the region because a 
specific equipment may see the clients moving at any time. 

The alternate approach to this would be to 
1) have the TPIA notify the operator each time a new client must be turned 

on. The operator would then reprovision the CMTS IP ranges accordingly. 
We're talking of a 7 to 10 days process here at least. Not acceptable. 
2) The TPIA would run the risk of running out of addresses each time 
the operator transfers Docsis domains between equipment, as there's 
practically no way to predict how many TPIA clients are in a specific
docsis/geographic domain. 

Both of the above being undesirable, the CRTC introduced the concept
of TPIA "region" to limit the problem. A TPIA may choose to be deployed
only in specific pre-defined geographic regions, limiting the need to 
provision equipement where no clients will ever be present. 

Even with the regionalization, most TPIAs still end up with very small 
numbers of clients spread across many equipments. Meeting ARIN's 
utilization constraints is therefore very difficult for any TPIA, 
especially when starting, because the distribution of clients over 
the different IP domains tends to be fairly uneven.

Here's a fictious example: a TPIA starts with a region containing 256
IP domains. The largest number of clients in a single domain is 35, 
but the average is only 18, for a total of 4600 clients. 
It requires 256 /26 to put in the network. This is a /18 with an 
utilization ratio of only 4600/65536 = 28%. 

If anyone has a solution to this problem that doesn't involve 
extensive operational subnet swapping, let's hear it! Otherwise, 
a change in policy is probably required. 


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