[Tmrg] Scenario for convergence time

[Lachlan Andrew]

Greetings all,

Here is my homework: the "convergence time" scenario.  I also realised
that we didn't mention a "hop count fairness" scenario, so I put a few
thoughts down for that too.

Test aims to determine how quickly existing flows make room for new flows.

Agreed on:
- Start with one flow in "equilibrium",
  10% "background traffic",
  one flow having aborted slow start with window size 2~4 (initial CWND)
- "Realistic" mix of RTTs for background traffic
- One measure is time for new flow to transmit
  10, 100, 1000, 10000  1500-byte packets.
  (Can be a *single* simulation/experiment, if we know when each byte is
  received.)

My Proposals:
- test equal RTTs, new RTT 4 times longer and 4 times shorter than existing.
- For equal RTTs and protocols with a loss component:
	time until window of new flow after window reduction is
	at least as large as min window of old flow after a reduction

To decide:
- What statistics of background traffic?
- What RTTs? 80 and 120/30?
- What bandwidth?  All? 100Mbps?
- Should it be specified in bytes instead of packets, to make it MTU-agnostic?
- Single link only?






Multi-bottleneck fairness:
Aim: Determine how much less bandwidth is given to a flow using
multiple bottlenecks than to a flow with equal RTT using only one of
those bottlenecks.

- 2, 3 link parking lot
- 3 link network with two two-link flows and a three-link flow
  (and three one-link flows?)  Especially important for hybrid loss/delay
- three hop ring with overlapping two-hop flows.  Need fancy routing?
- three link star.  Automatic bi-directional traffic.


Other issues:
- highly skewed RTTs
  (May not be "typical" but important/realistic/informative special case.)


Cheers,
Lachlan

-- 
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
http://netlab.caltech.edu/~lachlan