CRAWDAD ucsd/cse

To characterize the sources of delay in 802.11 production network, we collected comprehensive traces of wireless activity in the UCSD Computer Science building. date/time of measurement start: 2007-01-11date/time of measurement end: 2007-01-11 collection environment: To characterize the sources of delay in 802.11 production network, we collected comprehensive traces of wireless activity in the UCSD Computer Science building. The traces was collected on Thursday, January 11, 2007.network configuration: The production 802.11 network consists of 40 Avaya AP-8 802.11 b/g access points covering four floors and the basement. The APs are identically confiured (except for their channel assignment) and support both 802.11b and 802.11g without encryption. Our CSE wireless network has 40 APs. Their locations are in [labels.txt] and five .png files - [1st floor], [2nd floor], [3rd floor], [4th floor], and [basement].data collection methodology: We use the Jigsaw system described in [cheng-jigsaw] to collect the traces. Jigsaw is a distributed wireless monitoring platform that we have deployed in our department building to monitor the production 802.11 network. The hardware monitors consist of 192 radios interspersed between the infrastructure APs. The radios passively monitor the wireless network and report all wireless events across location, channel, and time via a private wired network to a back-end storage server. Jigsaw merges and time synchronizes these separate radio traces into a single, global uni ed trace. Moreover, Jigsaw performs this operation in real time; a single 2.2Ghz AMD Opteron server can synchronize one minute of raw trace data in under 15 seconds. We configure Jigsaw to capture the first 120 bytes of each wireless frame. As a result, the aggregate monitor traffic from all radios ranges from 2-10Mbps and is roughly five times the amount of production wireless traffic. limitation: Please be careful that the wired packet and the wireles packets are not 1-to-1 match: * Every wired packet may have many multiple 802.11 retransmissions. * APs only forward 802.11 data frames. Management, control, NULL frames only exist in 802.11 network. * The sniffers may pick up non-CSE AP signals. Similarly, the sniffers may miss CSE packets. * The wired gateway forwards broadcast traffic among other two nearby bulidings wireless VLAN.Tracesetucsd/cse/jigsaw Jigsaw traces of wireless activity in the UCSD Computer Science building.file:description: We used Jigsaw - a tool for analyzing wireless traffic - to collect comprehensive traces of wireless activity in the UCSD Computer Science building.measurement purpose: Network Diagnosismethodology: 1. SoftwareJigsaw is a tool for analyzing wireless traffic across locations, channels, time, and protocol layers. It takes traces from multiple sniffers at distinct vantage points, identifies and synchronize the duplicate wireless frames in the traces, rebuild link layer and transport layer conversasions. This version also includes a madwifi driver patch that reduces the overhead of excessive logging of PHY and CRC error events. Jigsaw is available under GPL licence.2. HardwareThe guts of our wireless node/sensor is a Soekris net4801 or net4826 embedded computer, which has a 266 Mhz 586 class CPU (Geode) single chip processor. The 4801 board includes one Compact Flash slot, three 10/100 ethernet ports, 128 Megabytes of RAM, serial ports, MiniPCI/PCI slot. In addition, 4801 has IDE port and two USB 1.1 ports. 4826 can be powered over Ethernet. Most of our nodes are 4826 boxes. The Compact Flash slot is loaded with a Compact Flash card (4801 has 256M, 4826 has 64M), used to store the moderately patched Pebble Linux image and related files. In normal operation the card is mounted in read-only mode to reduce wear and help ensure filesystem consistency in the face of power outages. A small portion of the memory is mounted for RW file system access. Each node is equipped with two Atheros-based 802.11 a/b/g wireless cards. Two NICs enable a broader range of experiments. The radio is attached to a 5dBi omni-directional attenna. We use heavily patched versions of the Atheros MadWiFi driver for these radios.Originally, the 4801 has a 20 Gigabyte (minimum) IDE hard disk. But we found hard disk failure is the major cause for crashes, so we removed them from 4801 boxes. Otherwise, the boxes are pretty stable and seldom crashes beside our own Kernel/drivers bugs. For our traffic monitoring project, all traces are directly dumped over NFS to one RAID 0 2 TB storage server. We have done several things to help us test new software and run experiments more conviently. First we install/re-install the kernels and other software through a master controller to keep all software synchronized and up-to-date automatically. It usually takes 1-2 minutes to re-install everything for all boxes. Since the kernel logs are gone after reboot because they are stored in memory file systems, we have all kernel logs remotely logged into our master server. This helps us to perform post-crash analysis or makes system management easier in general. In cases when the kernel hangs/panics or for some reason we can not login to perform a manual reboot, we can remotely reboot these boxes (and instruct them to boot to a stable kernel) in a minute. In addition, we use Geode CPU watch dog functions to make the boxes reboot themselves after certain timeout. Thus we minimize manual intervention for software update, experiements, and debugging. ucsd/cse/jigsaw Traceswireless: Jigsaw traces of wireless activity in the UCSD Computer Science building.configuration: the (merged) jigsaw traces collected using 192 sniffers in UCSD CSE building.format: The file is a series of jcap_hdr ([jcap_hdr.h]) packets like the pcap_pkthdr packet format. We created our own header simply to save spaces.ucsd/cse/tcpdumpTcpdump traces of wireless activity in the UCSD Computer Science building.file:description: We collected tcpdump traces of wireless activity in the UCSD Computer Science building.measurement purpose: Network Diagnosismethodology: The tcpdump trace was collected at the gateway router that interfaces the campus giga-ether network and the CSE wireless VLAN.ucsd/cse/tcpdump Tracewired: Tcpdump traces of wireless activity in the UCSD Computer Science building.configuration: the tcpdump trace at the gateway router that interfaces the campus giga-ether network and the CSE wireless VLAN.format: The format is gzipped tcpdump pcap.为刻画802.11（802.11）生产网络的时延来源，我们于加州大学圣地亚哥分校（University of California, San Diego, UCSD）计算机科学系大楼内采集了全面的无线活动追踪数据。测量开始时间：2007-01-11；测量结束时间：2007-01-11。 采集环境：为刻画802.11生产网络的时延来源，我们于2007年1月11日（周四）在UCSD计算机科学系大楼内采集了无线活动追踪数据。 网络配置：该生产级802.11网络包含40台Avaya AP-8 802.11 b/g无线接入点（Access Point），覆盖4层楼层与地下室。所有接入点除信道分配外配置完全一致，支持802.11b与802.11g协议且未启用加密。本系无线网络共部署40台接入点，其位置信息记录于[labels.txt]以及5个PNG格式文件：[1楼]、[2楼]、[3楼]、[4楼]及[地下室]。 数据采集方法：我们采用[cheng-jigsaw]中描述的Jigsaw系统采集追踪数据。Jigsaw是一套分布式无线监测平台，已部署于我系大楼以监控生产级802.11网络。监测硬件由192台无线网卡组成，分布于基础设施接入点之间。这些网卡被动监听无线网络，并通过专用有线网络将跨位置、信道与时间的所有无线事件上报至后端存储服务器。Jigsaw将这些独立的无线追踪数据合并并进行时间同步，生成单一的全局统一追踪数据。此外，Jigsaw可实时完成该操作：一台2.2GHz AMD Opteron服务器可在15秒内完成1分钟原始追踪数据的同步。我们将Jigsaw配置为捕获每个无线帧的前120字节。最终，所有网卡产生的总监测流量介于2-10Mbps之间，约为生产级无线流量的5倍。 数据集局限性：请注意，有线数据包与无线数据包并非一一对应： 1. 每个有线数据包可能对应多个802.11重传数据包； 2. 接入点仅转发802.11数据帧，管理帧、控制帧与空帧仅存在于802.11网络中； 3. 嗅探器可能捕获到非本系接入点的信号，同理也可能漏过本系无线数据包； 4. 有线网关会向附近另外两栋大楼的无线虚拟局域网（Virtual Local Area Network, VLAN）转发广播流量。 追踪集ucsd/cse/jigsaw： ucsd/cse/jigsaw：UCSD计算机科学系大楼内的Jigsaw无线活动追踪数据。 文件描述：我们采用用于分析无线流量的Jigsaw工具，采集了UCSD计算机科学系大楼内的全面无线活动追踪数据。 测量目的：网络诊断 采集方法： 1. 软件 Jigsaw是一款可跨位置、信道、时间与协议层分析无线流量的工具。它从不同观测点的多个嗅探器获取追踪数据，识别并同步追踪中的重复无线帧，重建链路层与传输层会话。本版本还包含madwifi驱动补丁，可降低对PHY与CRC错误事件的过度日志记录带来的开销。Jigsaw采用GPL许可证发布。 2. 硬件 本项目的无线节点/传感器核心采用Soekris net4801或net4826嵌入式计算机，搭载266MHz 586级Geode单芯片处理器。net4801主板包含1个CompactFlash插槽、3个10/100以太网端口、128MB RAM、串行端口、MiniPCI/PCI插槽，此外还带有IDE端口与2个USB 1.1端口。net4826支持以太网供电。本项目中大部分节点为net4826设备。 CompactFlash插槽搭载CF卡（net4801为256MB，net4826为64MB），用于存储经过适度补丁的Pebble Linux镜像及相关文件。正常运行时，该卡以只读模式挂载以减少磨损，并在断电时保障文件系统一致性；少量内存以读写模式挂载用于文件系统访问。每个节点配备2块基于Atheros的802.11 a/b/g无线网卡，双网卡可支持更广泛的实验场景。无线网卡连接5dBi全向天线。我们为这些网卡使用了经过大量补丁的Atheros MadWiFi驱动。 最初net4801配备20GB（最低配置）IDE硬盘，但我们发现硬盘故障是设备崩溃的主要原因，因此已从net4801设备中移除硬盘。除此之外，这些设备稳定性极佳，仅在出现内核/驱动错误时才会崩溃。 针对本流量监测项目，所有追踪数据均通过NFS直接转储至一台RAID 0架构的2TB存储服务器。 我们采取了多项措施以简化新软件测试与实验运行流程：首先，通过主控服务器安装/重装内核与其他软件，自动保持所有设备的软件同步并更新至最新版本，为所有设备重装所有软件通常耗时1-2分钟。由于内核日志存储于内存文件系统，重启后会丢失，因此我们将所有内核日志远程记录至主控服务器，这有助于崩溃后分析或简化日常系统管理。当内核挂起/恐慌或无法通过登录手动重启时，我们可在1分钟内远程重启这些设备，并指示其引导至稳定内核。此外，我们使用Geode CPU的看门狗功能，使设备在超时后自动重启，从而最大限度减少软件更新、实验与调试过程中的人工干预。 ucsd/cse/jigsaw 追踪集：UCSD计算机科学系大楼内的Jigsaw无线活动追踪数据。 配置：通过UCSD计算机科学系大楼内的192台嗅探器采集的（合并后）Jigsaw追踪数据。 格式：该文件为一系列采用jcap_hdr（[jcap_hdr.h]）格式的数据包，类似pcap_pkthdr数据包格式。我们自定义了该头部以节省存储空间。 追踪集ucsd/cse/tcpdump： ucsd/cse/tcpdump：UCSD计算机科学系大楼内的无线活动tcpdump追踪数据。 文件描述：我们采集了UCSD计算机科学系大楼内的无线活动tcpdump追踪数据。 测量目的：网络诊断 采集方法：该tcpdump追踪数据采集于连接校园千兆以太网与CSE无线虚拟局域网（VLAN）的网关路由器处。 ucsd/cse/tcpdump 追踪集：UCSD计算机科学系大楼内的无线活动tcpdump追踪数据。 配置：在连接校园千兆以太网与CSE无线虚拟局域网（VLAN）的网关路由器处采集的tcpdump追踪数据。 格式：该文件为gzip压缩的tcpdump pcap格式。