From: Gregg N 

"Geo"  wrote in news:428f8757$1{at}w3.nls.net:

> "Gregg N"  wrote in message
> news:Xns965D8F7E4B53Bgregginvalidinvalid{at}216.144.1.254...
>
>> > There is a do not fragment setting via that flag, who is that do
>> > not fragment setting supposed to instruct if not the routers? Is it
>> > just for a different network layer before the packet leaves the
>> > machine?
>>
>> The "don't fragment' flag requests that the next hop not fragment it
>> when it sends it on. It's for the same IP layer. I don't see how your
>> question is relevant to what you quoted about fragmentation not
>> requiring a response.
>
> If the router is fragmenting the traffic and buffering incoming
> traffic, there must be a mechanism to tell the local computers to hold
> up a minute because my buffer (me being the router) is full.

First, I don't see what fragmentation has to do with running out of buffer
space. Fragmentation in IP is just to accomodate the datalink/MAC layer.

But in any case, no, IP (and UDP) does not have any mechanism for telling
the sender to hold up. If the router runs out of buffer space, it can just
drop the packet. Recovery from this sort of thing is the responsibility of
higher layers such as TCP, which I am not using in my test.

Gregg

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