From nobody Wed Mar 5 21:58:04 2025 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Z7RJ95WfVz5qqFl for ; Wed, 05 Mar 2025 21:58:17 +0000 (UTC) (envelope-from y.jaeyong@gmail.com) Received: from mail-vk1-xa33.google.com (mail-vk1-xa33.google.com [IPv6:2607:f8b0:4864:20::a33]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "WR4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Z7RJ90rJnz3HY3; Wed, 05 Mar 2025 21:58:17 +0000 (UTC) (envelope-from y.jaeyong@gmail.com) Authentication-Results: mx1.freebsd.org; none Received: by mail-vk1-xa33.google.com with SMTP id 71dfb90a1353d-523909ec175so1696052e0c.0; Wed, 05 Mar 2025 13:58:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1741211896; x=1741816696; darn=freebsd.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=MI/QEFROHaWCm0iRrwFi5gZN+CUmvtIZrC1Sq3lp2AY=; b=m/raeotQCgqt4NapuESvV4oR6XPf39YvC+F5rqSX3q0yuu4pxlRQy5EogtD5aWN6cQ yqwtRB81Ert7BH38qvGUwQmOMZqoOegmUAV7kuBF1zjCImdiFE8iqRESfTbR1XPQyMyW lrAejGx0adZ5DuKNfAmwVUKaIdYlKcJPyxPtucdNfSyswbmlbKwfuho1E3F6YRZVU4b0 RgG0c7FrWzYEXZr+zQ9J00FF0f+HN8msUyNUn3/fTkPqLq2/SCsVAD9URikYV6r6ysWg KNMo3v1YaohPqFbbAKHvVAfj/gCrbGjsq45qJsKywHqD8lFMFXp3M+EYUTHyjq3dqV85 lBVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741211896; x=1741816696; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MI/QEFROHaWCm0iRrwFi5gZN+CUmvtIZrC1Sq3lp2AY=; b=gfv5CZEnFA53qlwtQ4UlRmpf4DxIFg8lPp2VKgLEhV7YbJoV4JoeNCk/llgnpDPH3Z 1b4fUkseqHw/tdnhKjcmv2BW6nCufjqoN0ox8pE11s0fnYmtsnpfYG5qRdrWqGu45OIi 4BLumhjLCInLYi9I5zjPwd62QGTx89VAMwJBO91nK2ihzhZcAQiA/X9cTLLQBVD/mOPq PdVK9zpaF6X8Q4hyevrqHbrXP036R3JBz/42DowCsIaSChD1s5Q+qWULFlKVU6pyItRL 3OxkskrRJmhj8pdS/ozLTX8nxbxDCTD8INnYZnonnwMD2IK9fjZDDinGmLwyS5JmjeEH mgeA== X-Gm-Message-State: AOJu0YxAeJogxGH3UBMjKH6hWHKVxdjYjzz9h5UaJHrlNxTVg1DcE6Au 32jPktVJwbkmMq9wQ97Ol9WYTardsqF3VaLGvw9+KEV4JjYlHWKQzVM4UjQs4nffU2cSGFgukSq wQZ0B71hRPVzE4KMqDXC9Q4FW+srlzjLD X-Gm-Gg: ASbGnct0As4OYjrHys8madVxSNRCApeExRWgBO+RZcuf9/OEhV8quUK+6OJ9OqHquq9 mV/kYz/jvkxkPlAM/ugC9dO5bq++mdFbXI073xVLmUIU1eUj9DiQ0dQ8VG+kmxtl6D4mGjWcyVd BbJgFiDh587S6rvaBhWVex7Pt72T/g9ew+Q6AjTzIh6F0s1OeytrZRmMKa43GU X-Google-Smtp-Source: AGHT+IEyRDUYLbTYURlhRC3Zk8A+R0ilJhffpOMnOrLa33bkPMHyTdu5/M8nePRrci3iTPBodWkw34lnnknZHMiNOBI= X-Received: by 2002:a05:6122:2a14:b0:520:42d3:91bc with SMTP id 71dfb90a1353d-523c61149b6mr3239457e0c.2.1741211895903; Wed, 05 Mar 2025 13:58:15 -0800 (PST) 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 References: <38B72ADC-B796-4BFC-8F94-2BD6E40C4231@freebsd.org> In-Reply-To: From: jaeyong yoo Date: Wed, 5 Mar 2025 16:58:04 -0500 X-Gm-Features: AQ5f1JqyvpjVzXvKV7ECoplgL548exlPqwUDb-XmfrwpUtlEUKj1jmzCKWZIxpw Message-ID: Subject: Re: Sending empty segment upon receiving partial ACK To: Cheng Cui Cc: freebsd-net@freebsd.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; TAGGED_FROM(0.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US] X-Rspamd-Queue-Id: 4Z7RJ90rJnz3HY3 X-Spamd-Bar: ---- Yes it is data retransmission but my concern is that the retransmission packet has the segment length of zero. If there is nothing to send, why don't we just not send it. What I meant by "no packets going out" is, that zero-length-segment can be considered as ACK to acknowledge some received packets but the sender of "zero-length-segment" did not receive any packets hence nothing to ACK. That said, those retransmission packets are the pure purpose of retransmissions and its segment length is zero, which seems pure overhead. Hope this makes it clear. Thanks, Jaeyong 2025=EB=85=84 3=EC=9B=94 5=EC=9D=BC (=EC=88=98) =EC=98=A4=ED=9B=84 12:30, C= heng Cui =EB=8B=98=EC=9D=B4 =EC=9E=91=EC=84=B1: > > > > On Feb 26, 2025, at 10:21, jaeyong yoo 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 r= etransmitting packets. But what do you mean "no packets going out"? > > Best Regards, > Cheng Cui > > >