Hi Ole,

Answers inline.

Cheers,
Ian

-----Original Message-----
From: Ole Trøan [mailto:[email protected]] 
Sent: Montag, 3. Dezember 2012 10:06
To: Farrer, Ian
Cc: [email protected]; [email protected]
Subject: Re: [Softwires] Unified Softwire CPE: draft-bfmk-softwire-unified-cpe

Ian,

> Whichever state is selected, NAT is certainly fundamental to how the state 
> will operate and so we tried to weave it into the functional description. I'm 
> not sure that provisioned NAT info enough to be able to use to unambiguously 
> define with operating 'mode' (for want of a better word) to use.
> 
> One of the reasons for the use of state in the draft is try and define the 
> operating modes with as little overlap as possible (it's not 100%, but 
> there's only 1 exception at the moment for binding mode and MAP1:1). From 
> this, then it is easier to align the specific solution names to the state 
> characteristics.

I don't think you should try to define modes such that the map (no pun 
intended) into the specific solution names.
shouldn't the purpose of a "unified CPE", be for the CPE not to have to care 
about the different "deployment modes" on the head end?

Ian: But a MAP CPE does have to care about what is on the tunnel head end as it 
could be another mesh client, or it could be the BR. It uses a different 
mapping rule type for each, so it is aware of the capabilities of the head end.

> But, with what you've suggested, there is more overlap, i.e. both 2&4 have 
> NAT functions that are supported by two different mechanisms.
> 
> However, what you've said does raise the following point:
> 
> The way that state is described in the draft at the moment is actually taken 
> from a concentrator perspective. This could be taken to be almost the inverse 
> of the amount of state that is required from the CPEs perspective (i.e. if 
> all of the state is in the providers network (DS-Lite), then the CPE doesn't 
> need it. If the providers network has less state ('per-customer', 
> 'stateless'), then the CPE needs to have more - i.e. dynamic state table for 
> NAT, configuration for local IPv4/port set, MAPing rules etc.
> 
> Would describing the different states more from the CPE's perspective make 
> this clearer?

that would certainly help. although I don't think "state" is the defining 
characteristic.

Ian: Is the problem with the what's being described (i.e. the content and 
functional differentiations) or the naming and terminology used to describe it?


cheers,
Ole
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