[e2e] local recovery or not local recovery, was: Re: Satellite networks latency and data corruption

[alok]

Detlef Bosau wrote:

> Christian Huitema wrote:
>
>> There are pros and cons to hop by hop and end to end control.
>> The nature of loss (weather events) implies that there is generally no
>> correlation between the error rates of the multiple hops. In practice,
>> only one hop will have a significant error rate, while the others will
>> be quasi free of errors.
>
>
> Could it be feasible then to insert ARQ IS-IS only around the 
> satellite link, which suffer from weather events?

A bit closer to what I was looking at,

I thought the concept of selective reject around a window would ensure 
this is how it behaves anyways?

However given:

A1---hop1----hop2--hop3--hop4---A2

a. does each hop reorder (no I think)
b. does each hop *only keep track of the window* and so SREJ and forward 
what it has received?
c. is the window relevant *only* between 2 hops?

More like

A1 has frames1--frames10

window is 5 between A1 and A2 (do intermediate nodes keep track of 
window size, or do they keep all the frames locally, which is what I was 
asking about buffer sizes??)

hop3 sees it has got frames1,2,4,5 (in a sequential order) but not 3

does hop3 send a SREJ back to hop2 for that frame3 *but* forwards the 
rest as and when they come in?  Ofcourse this would mean hop3 gets a 
SREJ from hop4 and hop4 from A2 and so on, but it in no way makes each 
node hold up the rest of the data.

so basically each hop knows the window and can induce a SREJ, but it 
does not in anyway "wait for the whole window".

Is this different from what it actually behaves like?

-thanks
Alok