[e2e] What's wrong with this picture?

Detlef Bosau detlef.bosau at web.de
Sun Sep 13 04:57:27 PDT 2009

Ken Calvert wrote:
> What I think is interesting about this discussion is that the original 
> "framers" [:-)] of TCP saw nothing wrong with an MSL denominated in 
> minutes, and now delivering a datagram after it spends 10 seconds in 
> the network is considered harmful.  In between came VJCC -- but we've 
> had that all these years and this is the first time I've heard anyone 
> suggest it's a problem that packets can survive in the network for 
> one-sixth of a minute.
> An MSL is required so TCP (or any *practical* reliable transport) can 
> have certain safety properties.  This discussion shows that MSL has 
> implications for the CC control loop as well.  TCP's correctness would 
> be fine if the MSL were 10 seconds, so *if* the consensus is that 
> multiple seconds of buffering is broken, why not acknowledge that the 
> world has changed and make that an "official" IETF policy?

Did I get you right: MSL = Maximum Segment Length?

Now, then the question is: what's the reason for a MSL of 10 seconds?

Is this the maximum segment _size_ of perhaps 50 Gigabytes, which 
requires this temporal extension?
Or is it a heroic effort link which is busy with the error free delivery 
of one or two bytes?

In the latter case, I wouldn't call that MSL but head of line blocking...

Detlef Bosau		Galileistraße 30	70565 Stuttgart
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