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fix the previous bug fix. #87

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Merged
huitema merged 1 commit into from
Dec 3, 2025
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fix the previous bug fix. #87

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14 changes: 7 additions & 7 deletions doc/c4-tests.md
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Expand Up @@ -184,22 +184,22 @@ capacity of the path. At the beginning of the simulation,
the simulated bandwidth is set at 5 Mbps. It increases to
10 Mbps after 2.5 seconds. The RTT remains constant at
100ms. The test verifies that 100 simulations of a
7MB download all complete in less than 7.9 seconds.
7MB download all complete in less than 8.6 seconds.

The goal of the test is to verify that C4 promptly
discovers the increase in bandwidth, and
increases the transmission rate.

### Drop and back

The "low and up" scenario simulates a sudden decrease in the
The "drop and back" scenario simulates a sudden decrease in the
capacity of the path, followed by return to normal.
At the beginning of the simulation,
the simulated bandwidth is set at 10 Mbps. It decreases
to 5 Mbps after 1.5 second, then returns to 10 Mbps
after 2 seconds. The RTT remains constant at
100ms. The test verifies that 100 simulations of a
7MB download all complete in less than 8.15 seconds.
7MB download all complete in less than 8.25 seconds.

The goal of the test is to verify that C4 adapts
promptly to changes in the available bandwidth on a
Expand All @@ -221,7 +221,7 @@ promptly after a short suspension of the path.

### Short to long

The "black hole" scenario simulates a sudden increase in the
The "short and long" scenario simulates a sudden increase in the
latency of the path.
At the beginning of the simulation,
the simulated RTT is set at 30ms. After 1 second, the
Expand Down Expand Up @@ -566,7 +566,7 @@ that changes to a 100ms RTT after 1 second.
The test lasts for 10 video groups of frames, i.e. 10 seconds.
The measurements start 5 seconds after the
start of the connection. The expected average delay is set to 110ms,
and the maximum delay is set to 126ms. The test is successful if
and the maximum delay is set to 127ms. The test is successful if
100 trials are all successful.

### Media over varying Wi-Fi
Expand Down Expand Up @@ -611,8 +611,8 @@ of 100 to 200ms every second. The data rate is set to 20Mbps, and the base
RTT before jitter is set to 2ms, i.e., simulating a local server.
The test lasts for 5 video groups of frames,
i.e. 5 seconds. The measurements start 200ms after the
start of the connection. The expected average delay is set to 105ms,
and the maximum delay is set to 410ms. The test is successful if
start of the connection. The expected average delay is set to 120ms,
and the maximum delay is set to 675ms. The test is successful if
100 trials are all successful.

# Tests
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72 changes: 36 additions & 36 deletions doc/c4-tests.txt
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Expand Up @@ -5,9 +5,9 @@
Network Working Group C. Huitema
Internet-Draft Private Octopus Inc.
Intended status: Informational S. Nandakumar
Expires: 5 June 2026 C. Jennings
Expires: 6 June 2026 C. Jennings
Cisco
2 December 2025
3 December 2025


Testing of Christian's Congestion Control Code (C4)
Expand Down Expand Up @@ -40,7 +40,7 @@ Status of This Memo
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on 5 June 2026.
This Internet-Draft will expire on 6 June 2026.

Copyright Notice

Expand All @@ -53,7 +53,7 @@ Copyright Notice



Huitema, et al. Expires 5 June 2026 [Page 1]
Huitema, et al. Expires 6 June 2026 [Page 1]

Internet-Draft C4 Tests December 2025

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Huitema, et al. Expires 5 June 2026 [Page 3]
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Huitema, et al. Expires 5 June 2026 [Page 4]
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Expand Down Expand Up @@ -266,7 +266,7 @@ Internet-Draft C4 Tests December 2025
of the path. At the beginning of the simulation, the simulated
bandwidth is set at 5 Mbps. It increases to 10 Mbps after 2.5
seconds. The RTT remains constant at 100ms. The test verifies that
100 simulations of a 7MB download all complete in less than 7.9
100 simulations of a 7MB download all complete in less than 8.6
seconds.

The goal of the test is to verify that C4 promptly discovers the
Expand All @@ -277,19 +277,20 @@ Internet-Draft C4 Tests December 2025



Huitema, et al. Expires 5 June 2026 [Page 5]
Huitema, et al. Expires 6 June 2026 [Page 5]

Internet-Draft C4 Tests December 2025


2.2.5. Drop and back

The "low and up" scenario simulates a sudden decrease in the capacity
of the path, followed by return to normal. At the beginning of the
simulation, the simulated bandwidth is set at 10 Mbps. It decreases
to 5 Mbps after 1.5 second, then returns to 10 Mbps after 2 seconds.
The RTT remains constant at 100ms. The test verifies that 100
simulations of a 7MB download all complete in less than 8.15 seconds.
The "drop and back" scenario simulates a sudden decrease in the
capacity of the path, followed by return to normal. At the beginning
of the simulation, the simulated bandwidth is set at 10 Mbps. It
decreases to 5 Mbps after 1.5 second, then returns to 10 Mbps after 2
seconds. The RTT remains constant at 100ms. The test verifies that
100 simulations of a 7MB download all complete in less than 8.25
seconds.

The goal of the test is to verify that C4 adapts promptly to changes
in the available bandwidth on a path.
Expand All @@ -308,11 +309,12 @@ Internet-Draft C4 Tests December 2025

2.2.7. Short to long

The "black hole" scenario simulates a sudden increase in the latency
of the path. At the beginning of the simulation, the simulated RTT
is set at 30ms. After 1 second, the latency increases to 100ms. The
data rate remains constant at 100ms. The test verifies that 100
simulations of a 20MB download all complete in less than 22 seconds.
The "short and long" scenario simulates a sudden increase in the
latency of the path. At the beginning of the simulation, the
simulated RTT is set at 30ms. After 1 second, the latency increases
to 100ms. The data rate remains constant at 100ms. The test
verifies that 100 simulations of a 20MB download all complete in less
than 22 seconds.

The goal of the test is to verify that C4 react properly exercises
the "slow down" mechanism to discover the new RTT.
Expand All @@ -331,9 +333,7 @@ Internet-Draft C4 Tests December 2025





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Huitema, et al. Expires 5 June 2026 [Page 9]
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Huitema, et al. Expires 5 June 2026 [Page 10]
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Expand Down Expand Up @@ -708,7 +708,7 @@ Internet-Draft C4 Tests December 2025
that changes to a 100ms RTT after 1 second. The test lasts for 10
video groups of frames, i.e. 10 seconds. The measurements start 5
seconds after the start of the connection. The expected average
delay is set to 110ms, and the maximum delay is set to 126ms. The
delay is set to 110ms, and the maximum delay is set to 127ms. The
test is successful if 100 trials are all successful.

2.8.5. Media over varying Wi-Fi
Expand All @@ -725,7 +725,7 @@ Internet-Draft C4 Tests December 2025



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Expand Down Expand Up @@ -757,8 +757,8 @@ Internet-Draft C4 Tests December 2025
before jitter is set to 2ms, i.e., simulating a local server. The
test lasts for 5 video groups of frames, i.e. 5 seconds. The
measurements start 200ms after the start of the connection. The
expected average delay is set to 105ms, and the maximum delay is set
to 410ms. The test is successful if 100 trials are all successful.
expected average delay is set to 120ms, and the maximum delay is set
to 675ms. The test is successful if 100 trials are all successful.

3. Tests

Expand All @@ -781,7 +781,7 @@ Internet-Draft C4 Tests December 2025



Huitema, et al. Expires 5 June 2026 [Page 14]
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Expand Down Expand Up @@ -837,7 +837,7 @@ Authors' Addresses



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2 changes: 1 addition & 1 deletion sim_specs/c4_drop_and_back.txt
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Expand Up @@ -2,7 +2,7 @@ main_cc_algo: c4
main_start_time: 0
main_scenario_text: =b1:*1:397:7000000;
nb_connections: 1
main_target_time: 8150000
main_target_time: 8250000
data_rate_in_gbps: 0.01
latency: 50000
queue_delay_max: 80000
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2 changes: 1 addition & 1 deletion sim_specs/c4_low_and_up.txt
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Expand Up @@ -2,7 +2,7 @@ main_cc_algo: c4
main_start_time: 0
main_scenario_text: =b1:*1:397:7000000;
nb_connections: 1
main_target_time: 7950000
main_target_time: 8600000
data_rate_in_gbps: 0.01
latency: 50000
queue_delay_max: 80000
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2 changes: 1 addition & 1 deletion sim_specs/c4_media_short_long.txt
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Expand Up @@ -11,6 +11,6 @@ qlog_dir: cclog
qperf_log: c4_media_sl_qperflog.csv
media_stats_start: 5000000
media_latency_average: 110000
media_latency_max: 126000
media_latency_max: 127000
media_excluded: vhigh, vmid, vlast
link_scenario: 1000000:U0.01:D0.1:L15000:Q100000;60000000:U0.01:D0.1:L50000:Q200000
4 changes: 2 additions & 2 deletions sim_specs/c4_media_wb.txt
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Expand Up @@ -12,6 +12,6 @@ icid: ed1ac4fb
qlog_dir: cclog
qperf_log: bbr_media_wf_qperflog.csv
media_stats_start: 200000
media_latency_average: 105000
media_latency_max: 410000
media_latency_average: 120000
media_latency_max: 675000
media_excluded: vhigh, vmid, vlast