Re: Review of draft-bberry-pppoe-credit (Informational)

On 27 Jul, James Carlson wrote:
> Mark Townsley writes:
>> This is an individual submission document for Informational publication. 
>> Without getting into whether PPPoE itself should have been strangled at 
>> birth or not, I would like a fair review of this document before 
>> advancing it. Please send comments to the authors and this list before 
>> August 24.
> 
> I suppose I'm a bit curious why the existing RFC 1663 (PPP Reliable
> Transmission) and RFC 1989 (PPP Link Quality Monitoring) protocols
> weren't already sufficient for the job and, if not sufficient,
> couldn't have been built on to solve the problem.  I don't see either
> mentioned in the draft as related work.

I don't really see how these are connected.

The goal as suggested in the draft is not to create a "reliable" link.
It's more to avoid creating a hopelessly unreliable link.  The target
environment is one where a router is connected to a radio by 
by a fast link (an ethernet), and where there are multiple PPP sessions
being established between the router and the numerous remote nodes reachable 
by the radio.  The radio equipment itself doesn't maintain either a fast or
reliable connection to the other nodes in its contact list.  The radio 
equipment *does* buffer (possibly even on a per PPP connection basis), 
but has limited capacity.  The radio equipment may even include some limited
retransmission capability, but overall it's not going to provide a 
guaranteed delivery of packets.  Further, since the radio is a broadcast
mechanism and sharing the frequency with all the other nodes in that
network, the rate of packet delivery is very erratic and there's no
meaningful bandwidth which can be associated to the individual PPP
connections.

Imagine a bunch of ham radio operators running PPP on the mobile
radios in their cars, creating a very fluid network, and you'll
have a good mental picture of the target environment (the draft
doesn't seem to make this really clear).

Please note, BTW, that I am not trying to push or endorse the draft;
or trying to suggest that other methods may not also be worth
considering.  I'm just trying to add some background which may help
clarify the intent behind the draft.

-Mark Lanzo




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