[e2e] TCP to exhibit MTU unfairness?

Lachlan Andrew lachlan.andrew at gmail.com
Tue Nov 13 14:10:17 PST 2007

Greetings Detlef,

On 13/11/2007, Detlef Bosau <detlef.bosau at web.de> wrote:
> Hm. Just a question on RTT fairness: Is it intended to have the same RTT
> for competing flows sharing a bottleneck?

No, in general flows will have different RTTs.  I was just mentioning
that some flow control algorithm aim to give them an equal share of
the capacity, despite having unequal RTTs.

> However, when TCP congestion control achieves fairness of capacity
> usage, I would well accept when two competing flows do not achieve
> exactly the same throughput although they share a common bottleneck. Do
> you agree here?

Fairness between heterogeneous flows is complicated.  If a flow
traverses multiple congested links, it is sensible to give it a lower
rate than others using only one of those links.  However, I haven't
seen any compelling reason that the rates should depend on RTT or
packet size.

I wasn't meaning to get into a debate about fairness; I was just
explaining Daniel's original post.


Lachlan Andrew  Dept of Computer Science, Caltech
1200 E California Blvd, Mail Code 256-80, Pasadena CA 91125, USA
Ph: +1 (626) 395-8820    Fax: +1 (626) 568-3603

More information about the end2end-interest mailing list