Bug 2832 – TCP Repeated Retransmission

Bug 2832 - TCP Repeated Retransmission


Summary:	TCP Repeated Retransmission

Status:	RESOLVED FIXED

Product:	ns-3
Classification:	Unclassified
Component:	tcp
Version:	ns-3.27
Hardware:	All All

Importance:	P3 critical
Assigned To:	natale.patriciello

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2017-11-30 17:03 UTC by Menglei Zhang
Modified:	2018-03-03 06:01 UTC (History)
CC List:	3 users (show)

See Also:

Attachments
original/ fixed TCP sequence plot (320.86 KB, image/png) 2017-11-30 17:03 UTC, Menglei Zhang	Details
Script to recreate the TCP sequence plot (4.10 KB, text/x-csrc) 2017-11-30 17:05 UTC, Menglei Zhang	Details
A patch file to fix this bug (636 bytes, patch) 2017-11-30 17:06 UTC, Menglei Zhang	Details \| Diff
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Description Menglei Zhang 2017-11-30 17:03:13 UTC

Created attachment 2967 [details]
original/ fixed TCP sequence plot

In the TcpSocketBase class, Selective ACK(SACK) is enabled by default and triggers retransmissions after loss events. However, the partial ACK also triggers retransmissions, even if the SACK is enabled. Therefore the same packet is retransmitted twice. According to RFC 6592 https://tools.ietf.org/html/rfc6582, the fast recovery for partial ACK should be used in the absence of SACK. Here I attached a figure to show the original TCP sequence plot and the fixed one.

Comment 1 Menglei Zhang 2017-11-30 17:05:35 UTC

Created attachment 2968 [details]
Script to recreate the TCP sequence plot

Comment 2 Menglei Zhang 2017-11-30 17:06:14 UTC

Created attachment 2969 [details]
A patch file to fix this bug

Comment 3 natale.patriciello 2018-03-03 06:01:34 UTC

Fixed in  13372:950f852a89f9