DOI: 10.21227/kpka-vg74
title: CRAWDAD ucsd/cse

description: 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.