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example-2-fullscale

README.md

Example 2 — full-scale Scenario 2 reconstruction

Author: Sergio Andreozzi Dates: April 16, 2026 Notes: Full-scale reconstruction of thesis Scenario 2 (§4.2) — 469-node AF PHB importance differentiation via a 6-way WRED parameter sweep over Telnet / FTP / HTTP traffic through an SFQ-scheduled DiffServ bottleneck.

This is a 2026 reconstruction by the original author; the 2006 DiffServ4NS release shipped only the 13-node demonstration in the sibling example-2/ directory, never the 469-node thesis scenario. For the full reconstruction narrative — the two documented deviations from thesis text (HTTP approximation, FTP calibration), thesis-fidelity validation across all six WRED parameter sets, and the negative-result http_bursty_session experiment — see VALIDATION.md.

Files

File Purpose
scenario-2.tcl Main simulation (469 nodes, 5000 s default)
smoke-test.tcl Smoke check (100 s, set 1)
utils.tcl Tcl helpers (Application/HTTP subclass, etc.)
wred-parameter-sets.md Verified WRED thresholds from thesis Figure 4.3
scenario-2-ns235.tcl Port-based variant for ns-2.35
scenario-2-ns235-srtcm.tcl srTCM per-flow variant for ns-2.35
smoke-test-ns235.tcl Smoke check for the ns-2.35 variant
smoke-bug9-phaseA.tcl, smoke-bug9-phaseC2.tcl WebTraf BUG-9 regression checks (ns-2.35)
VALIDATION.md Reconstruction narrative + thesis-comparison results

Requirements

Script ns-2 version
scenario-2.tcl, smoke-test.tcl 2.29
scenario-2-ns235.tcl, scenario-2-ns235-srtcm.tcl, smoke-test-ns235.tcl, smoke-bug9-phaseA.tcl, smoke-bug9-phaseC2.tcl 2.35

Simulation

From the project root directory:

docker run --rm \
  -v "$(pwd)/ns2/ns-allinone-2.29.3:/ns-allinone" \
  -v "$(pwd)/ns2/diffserv4ns/examples/example-2-fullscale:/scripts" \
  -v "$(pwd)/output/ns2/example-2-fullscale:/scripts/output/ns2/example-2-fullscale" \
  -w /scripts \
  -e LD_LIBRARY_PATH=/ns-allinone/otcl-1.11:/ns-allinone/lib \
  -e TCL_LIBRARY=/ns-allinone/tcl8.4.11/library \
  ubuntu:18.04 \
  /ns-allinone/ns-2.29/ns scenario-2.tcl SET

where SET is 1..6 (WRED parameter set). Each run takes ~1–2 min wall clock. Output files ServiceRate.tr, QueueLen.tr, PktLoss.tr, run.log are written to output/ns2/example-2-fullscale/set-SET/.

To run the full 6-way sweep, iterate SET=1..6, then parse via:

python3 scripts/scenario2-table44.py \
  > output/ns2/example-2-fullscale/table-4-4-reproduction.md

Topology

  servers (n6-n45)
  40 nodes via n2-n5
      \  |  /  /
       n2  n3  n4  n5                clients (n46-n465, 420 nodes)
        \  |  /  /                       |
         \ | / /                          \
          n1 <----[n466]<------ n0 <----+
                                  |      |
                                  |      | DiffServ edge (n0 -> n466):
                                  |      |   3 Mb/s, 20 ms, dsRED
                                  |      |   2 queues, SFQ(17:3)
  n467 <----------------[n0 ]    |      |   AF (85%) + Default (15%)
  n468 <----------------[n466]   |
                                 BG CBR

Total 469 nodes. Bottleneck: n0 -> n466 egress interface.