[e2e] Lost Layer?

[Detlef Bosau]

Am 12.02.2014 21:55, schrieb Ivancic, William D. (GRC-RHN0):
> Hence the lost layer.

Or not the lost layer. Admittedly, I'm a bit annoyed by the term "layer".
>
> IMHO, IP is can be viewed in some respects as just a multi-hop forwarding
> system.  The problem is TCP used IP point-of-attachment (POA) addresses as
> it's end-point identifiers.  

That's not a problem, that's IP.

> So, if you are mobile (your IP POA changes)
> or are multi-homed (you have more than one POA), then TCP doesn't handle
> this well. 

We should be precise here: TCP doesn't handle this at all.
TCP doesn't care about the path or path changes. (Or, nasty me, about
path capacity changes, which may happen every few milliseconds,
particularly in multi-homed scenarios.)

>  Mobile-ip is sort of a misnomer as mobile-ip is really there
> to make the POA used by layers above IP appear unchanged. 

Hence, the "layering" covers the reality behind some kind of neat
masquerade.

>  So then you
> implement mobile-ip, SCTP and HIP and other techniques to try and overcome
> the problem which is really a lost-layer problem (i.e. A incomplete or
> poorly architected network).

What I want to advocate is a model of flows. Not of layers but of flows.
We use this in multimedia systems for years.
Only in TCP, we insist of this "transparent IP cloud". This abstraction
is much to coarse IMHO.

>
> Will
>
>
>
>
>
>
> On 2/12/14 2:46 PM, "Detlef Bosau" <detlef.bosau at web.de> wrote:
>
>> Am 11.02.2014 22:20, schrieb Richard Bennett:
>>> Mobile makes this a relevant issue today and in the future. There's a
>>> lot of functional richness below IP, without which IP datagrams would
>>> never get delivered. Personally, I've always regarded IP as a stub or
>>> a placeholder for a real protocol, but I don't think APIs and
>>> protocols are interchangeable.
>>>
>>> RB
>> However, it is exactly this functional richness, which renders the
>> traditional end to end view, that a TCP flow is controlled from the end
>> points and only from the endpoints, highly questionable.
>>
>> IP and TCP/IP are expected to cope with mobile links. That's the reason
>> why I bother the community with my (sometimes nasty) view on the matter.
>>
>> -- 
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>> Detlef Bosau
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>>


-- 
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Detlef Bosau
Galileistraße 30   
70565 Stuttgart                            Tel.:   +49 711 5208031
                                           mobile: +49 172 6819937
                                           skype:     detlef.bosau
                                           ICQ:          566129673
detlef.bosau at web.de                     http://www.detlef-bosau.de