[e2e] Fwd: Re: Once again buffer bloat and CC. Re: A Cute Story. Or: How to talk completely at cross purposes. Re: [ih] When was Go Back N adopted by TCP

[Detlef Bosau]

As far as I see, DPR's idea is to gather congestion information along
the path using Bloome Filters.

There is one possible problem, which also arises with hopwise credit
based flow control: The Internet is basically an overlay network.
So an important issue, sometimes gets a bit lost, is that "adjacent" IP
nodes are - though being adjacent - not always connected by a point to
point link but there may be a more or less complex infrastructure in
between.

Now, congestion may well occur on nodes BETWEEN the IP nodes. (E.g.
Ethernet bridges, think of remote bridging as used in ADSL.)

The IP packet's payload is not accessible for those "L2 nodes", hence
these nodes cannot stamp packets with any actual congestion information.

As a consequence, imminent congestion may not be visible for the IP
based overlay network.

Detlef