[ih] why did CC happen at all?

[Detlef Bosau]

Am 02.09.2014 um 18:23 schrieb Louis Mamakos:
> On Sep 2, 2014, at 11:45 AM, Detlef Bosau <detlef.bosau at web.de> wrote:
>
>> (These days, I had to think about this funny "UDP light" with checksums
>> only referring to the headers, not to the payloads. Dear readers, there
>> is exactly NOT EVEN ONE wireless PACKET SWITCHING network without link
>> layer checksums, hence, a packet with bit errors is discarded at L2, not
>> at L4. So, when one introduces UDP light, the sad truth is: This dead is
>> died long ago before a packet ever reaches the receiver's access point
>> for "UDP".)
> Having been personally screwed by exactly this assumption more than once,
> I beg to disagree.
>
> End-to-end checksums are used to protect against software and random hardware
> errors anywhere along, not just corruption in transit over communication
> links.


We're talking a bit at cross purposes.

My perspective is a scientific one, not a UHD perspective.

So, the main purpose of my remark is to discuss "UDP lite" as some kind
of related work.
My basic assumption is always that hardware works as designed.
>
> 1. Early DEC DEUNA UNIBUS ethernet controllers would occasionally screw up
> the DMA transfers into memory, and corrupt a received packet when one of
> the transfers went wrong.  Fortunately, it didn't randomly spew the
> payload elsewhere in memory, but the packet was broken.  I'm sure fancy
> new ethernet interfaces with multiple queues would NEVER have this sort of
> problem.  This notion of checksum offload on NICs still gives me the willies.
>
> 2. Anyone remember HSSI and ATM DXI interfaces on your routers?  This was
> early in the deployment of ATM, and you could get this external device 
> that was a combination of an DS3 CSU/DSU and an ATM SAR.  There was this
> DXI protocol a router could speak to send and receive frames on ATM virtual
> circuits.  The external ATM frame shredder would do all of the SAR functions
> because the router interfaces didn't exist yet.

May be. But this is implementation. When I started this discussion, I
wanted to discuss the history of congestion control,


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