Presentation is loading. Please wait.

Presentation is loading. Please wait.

On the Use of Fixed Point Approximations to Study Reliable Protocols over Congested Links Michela Meo Michele Garetto Renato Lo Cigno Marco Ajmone Marsan.

Similar presentations


Presentation on theme: "On the Use of Fixed Point Approximations to Study Reliable Protocols over Congested Links Michela Meo Michele Garetto Renato Lo Cigno Marco Ajmone Marsan."— Presentation transcript:

1 On the Use of Fixed Point Approximations to Study Reliable Protocols over Congested Links Michela Meo Michele Garetto Renato Lo Cigno Marco Ajmone Marsan Globecom 2003

2 Access link scenario Q clients servers λ c conn/s Arrival process of new connections data packets

3 Access link scenario Ingoing traffic Outgoing traffic Uncongested link: Congested link:

4 Definition of “ g ”  The “normalized goodput” g (or “nominal link utilization”) on the link is defined as follows:  The actual traffic intensity  includes also retransmissions arriving at the link

5  Only necessary retransmissions:

6  Addition of un-necessary retransmissions:

7 Un-necessary retransmissions: the  parameter

8 Average Packet Loss Probability ( p ) Traffic Intensity (  ) M/M/1/B B = 16 B = 32 B = 64 TCP g = 0.90 g = 0.95 g = 0.98 Convergence of the FPA (unique solution)

9 Packet loss probability ( p ) Load (  ) TCP - Link utilization (g) = 0.95 M/M/1/B (B = 32).

10 Convergence of the FPA (double solution) Stable point Unstable point

11 flow dist ~ geom (20) Average Packet Loss Probability (p) Normalized Goodput (g) flow dist ~ geom (600) flow dist ~ geom (60) 1 stable solution 1 unstable solution 1 stable solution Stability region ns simulations: B = 128

12 g = 0.986

13 Fig. 6


Download ppt "On the Use of Fixed Point Approximations to Study Reliable Protocols over Congested Links Michela Meo Michele Garetto Renato Lo Cigno Marco Ajmone Marsan."

Similar presentations


Ads by Google