[e2e] Reasons not to deply TCP BIC/Cubic

Barry Constantine Barry.Constantine at jdsu.com
Wed Nov 30 04:23:44 PST 2011

Hi Saverio,

Does Windows 7 use this TCP implementation as well?

Thank you,
Barry Constantine

-----Original Message-----
From: end2end-interest-bounces at postel.org [mailto:end2end-interest-bounces at postel.org] On Behalf Of mascolo at poliba.it
Sent: Wednesday, November 30, 2011 6:11 AM
To: end2end-interest at postel.org
Subject: [e2e] Reasons not to deply TCP BIC/Cubic

Dear all,

we know that TCP BIC/Cubic is default in Linux and as a consequence  
50% of servers employs TCP BIC/Cubic.

Our measurements say that there could be reasons not to deploy TCP  
BIC/Cubic. These reasons  are in our opinion rooted in its more  
aggressive probing phase. In particular, in common network conditions,  
TCP BIC/CUBIC exhibits: 1. a larger RTT average wrt to TCP NewReno or  
TCP Westwood+; 2. a larger number of retransmission wrt to TCP NewReno  
or TCP Westwood+; 3 larger throughput but same goodput wrt to TCP  
NewReno or Westwood+.

In other terms, it seems that its more aggressive probing increases  
both throughput and retransmissions but leaving unchanged the goodput.  
This is  neutral for the users but negative for the network.

I appreciate your views.

Thanks for the attention and best regards,

Saverio Mascolo

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