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Wed, 05 Mar 2025 09:30:02 -0800 (PST) Received: from smtpclient.apple ([2600:1700:841:34f0:4c0:8dd4:f274:4167]) by smtp.gmail.com with ESMTPSA id 00721157ae682-6fe4e6bef3csm2548957b3.124.2025.03.05.09.30.01 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Mar 2025 09:30:01 -0800 (PST) From: Cheng Cui Message-Id: Content-Type: multipart/alternative; boundary="Apple-Mail=_A446C5C1-69FE-4717-80CE-497157D2D02C" List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@FreeBSD.org Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.400.131.1.6\)) Subject: Re: Sending empty segment upon receiving partial ACK Date: Wed, 5 Mar 2025 12:29:30 -0500 In-Reply-To: Cc: freebsd-net@freebsd.org To: jaeyong yoo References: <38B72ADC-B796-4BFC-8F94-2BD6E40C4231@freebsd.org> X-Mailer: Apple Mail (2.3826.400.131.1.6) X-Spamd-Result: default: False [0.28 / 15.00]; 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TAGGED_RCPT(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[209.85.128.174:from] X-Rspamd-Queue-Id: 4Z7KLg1j0qz3D4K X-Spamd-Bar: / --Apple-Mail=_A446C5C1-69FE-4717-80CE-497157D2D02C Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii > On Feb 26, 2025, at 10:21, jaeyong yoo wrote: >=20 > Yes that behavior was observed during recovery phase and during that > time frame, there were no packets going out to the other direction so > there is no reason to send pure ACK (and the ack number for those 3 > acks are the same and no possibility of challenge ack as well). Isn't loss recovery phase used for data retransmission? There should be = retransmitting packets. But what do you mean "no packets going out"? Best Regards, Cheng Cui --Apple-Mail=_A446C5C1-69FE-4717-80CE-497157D2D02C Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

On Feb 26, 2025, at 10:21, jaeyong yoo = <y.jaeyong@gmail.com> wrote:

Yes = that behavior was observed during recovery phase and during = that
time frame, there were = no packets going out to the other direction so
there is no reason to = send pure ACK (and the ack number for those 3
acks are the same and no = possibility of challenge ack as = well).

Isn't loss recovery = phase used for data retransmission? There should be retransmitting = packets.  But what do you mean "no packets going out"?

Best Regards,
Cheng Cui



= --Apple-Mail=_A446C5C1-69FE-4717-80CE-497157D2D02C--