From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f177.google.com (mail-pg1-f177.google.com [209.85.215.177]) by dpdk.org (Postfix) with ESMTP id A8A1E1B49C for ; Wed, 26 Sep 2018 20:28:49 +0200 (CEST) Received: by mail-pg1-f177.google.com with SMTP id g2-v6so6380971pgu.11 for ; Wed, 26 Sep 2018 11:28:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fluidic-io.20150623.gappssmtp.com; s=20150623; h=to:from:subject:message-id:date:user-agent:mime-version :content-language; bh=t3K7baaY3OR1hrmaBXzY/VNve63lAqT/3LV3thMKBdQ=; b=JGKifG+yggTw6NZ1Z3CfPfda+ge9cNDc0k5Um8itLLN9gRGqFxYZMhUeaOuqvGJEFQ f6cu5PdDYsVwpzToLZASzl9fKzEkaIdUTmKfDpAulXkTqHXRBwcDD7QnnMgiLL2R/FVR 3t1JgKNyI3yJF29W7mgiLEWbVjEltrd/3KA9HbANZq5LVFdwt/uW2edhEBaQvnxKPdmL xCOLrfAbuPY3Ygbg/rZ/WLDHZQRerxPXApuHHNx9OJ62dgDudvUxWgwhcQg0QSvx2d00 5Ypg2lPeF/cwf03VyWwhSOdB/XlJRlWBUsRMHsHDDsfAtxTBXLl9JjFNhHxLrHTVieoE oldA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version:content-language; bh=t3K7baaY3OR1hrmaBXzY/VNve63lAqT/3LV3thMKBdQ=; b=TiOD4o5c9ZowvvcDLVDv1VDnxeArh6woEkbLyf4eo2uhG1gsA5v8e6Kv1P9ZM+mQwG XjsPHiAUxjG/EEkaVylzgAYhZk1V4Zauz8b9Zp0oj+ItDnPk3NnAO2qBmSlNnK7UJ7c/ RYcNrSCPoGL9AJnVHjmCmBDrl0Ad35OFZhxTvku/Kqzq5fTNnryPmpDDDB3D/4Ag6dgq XlWsdoaMwWEJgbC+eeLCm0pmSX6w5PEmJsZ7SnEMjaZVU3RRbAUW0V3PG+2lYh859J1w iedkXyYGhN4OyOk7GPe73kllqVUi0o+CmR2kvUquIs+7iSgZec0XGepP+aBSw1QMPePO uLMA== X-Gm-Message-State: ABuFfogh5QPs9OVpssdxxzAexYnEUCNkFAC2ZIPjaZ1ZLOi+YHi4tqO3 EpdJS152WWmGAK4MQUjpTrI4muWL+9k= X-Google-Smtp-Source: ACcGV60ReluSJ94BhtUX8ar1sqC0DnHVOoUyVL2+JrbQI7OLp7qtMUlmS76GXuJVlj9a8LAohUcDhA== X-Received: by 2002:a63:fb07:: with SMTP id o7-v6mr6780926pgh.333.1537986528391; Wed, 26 Sep 2018 11:28:48 -0700 (PDT) Received: from [192.168.0.111] ([121.166.61.79]) by smtp.gmail.com with ESMTPSA id e26-v6sm7751433pfi.70.2018.09.26.11.28.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Sep 2018 11:28:47 -0700 (PDT) To: users@dpdk.org From: DoHyung Kim Message-ID: <034c4fb9-0f1d-78b7-0caf-6cb8c9ce2f09@fluidic.io> Date: Thu, 27 Sep 2018 03:28:44 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 Content-Language: en-US Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: [dpdk-users] Sent a UDP packet, but length is wrong when captured X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Sep 2018 18:28:50 -0000 Hi, I'm new to DPDK and having trouble in crafting TX packets. My application receives and caches UDP packets after dropping header part. When clients request, it sends the cached packets after prepending them a new header mbuf (by chaining), which contains all the headers to UDP's filled correctly for targeting the clients. Though I think I'm doing nothing wrong, I see the transmitted ethernet frames are 14 bytes longer than expected. Please see a capture of such a packet from Wireshark below: The multi-seg mbuf is 1370 byte long, but weirdly enough, its 1384 when captured back. I'm using libpcap based vdev on loopback interface for testing. And DPDK version is 17.11.3 on Ubuntu 18.04. Any clue? Thanks in advance. DoHyung Kim