The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL

The UNIVERSITY of NORTH CAROLINA at CHAPEL HILL Trace collection in the UNC-CH Di. RT lab 1

Outline Ø Monitoring location and UNC network Ø Setup specs - infrastructure Ø Process sequence overview Ø Live demo Ø Post-processing Ø Our experimental infrastructure and its capabilities 2

Trace collection point UNC-CH network Internet & Internet 2 Monitor w/ DAG card 3

Infrastructure • Monitor specs: P 4 1. 8 GHz CPU, 1. 4 GB RAM, 5*32 GB hard drives, Free. BSD 4. 7. • DAG 4. 3 GE dual interface 1000 Base-SX Gigabit Ethernet 133 MHz PCI-X card. 4

Process sequence overview packet capture using dagsnap analyze and present results convert to tcpdump format using dagconvert run (100 s of) tmix experiments in the lab anonymize using tcpdpriv create connection vectors in tmix 5

Demo 1. /usr/local/bin/dagsnap -d /dev/dag 0 -s 300 -v -o test. dag 2. dagconvert -Terf: pcap -i. . /test. dag -f b > test. b. tcpdump 3. dagconvert -Terf: pcap -i. . /test. dag -f a > test. a. tcpdump 4. /usr/dirt/src/tcpdpriv-1. 1. 10/tcpdpriv -P 99 -A 60 -M 20 -t mapping_file -r test. a. tcpdump -w test. a. anon. tcpdump 5. /usr/dirt/bin/4. x/tcpdump-hiperf -I -S -n -tt -r test. a. anon. tcpdump tcp > test. a. anon. tcpdump. txt (-I Print IP header fields (ttl, id and length)) 6

Packet capture • Usage: dagsnap [options] • -d <device> DAG device name • -h display help (this page) • -j Maximize disk write performance - will only write in chunks • -m <mebibytes> Maximum amount of data to write per call in Mi. B (default 4) • -o <filename> output file name (default is stdout) • -s <seconds> runtime in seconds • -v increase verbosity • With -v three columns are printed per second. • 1. The cumulative total of data written out. • 2. The buffer occupancy. Small values indicate no packet loss. • 3. The rate at which data is currently being written. 7

Convert dag to tcpdump • dagconvert: DAG file conversion utility: Usage: dagconvert [options] • -d <device> DAG device name • -h display help (this page) • -v increase verbosity • -i <filename> input file • -o <filename> output file • -r N[k|m|g] change output file after N Bytes. • k, m, g suffixes for kilobytes, megabytes, gigabytes. • -s <snaplen> output snap length • -t <seconds> capture period in seconds • -T <in_type: out_type> input and output types (see list of types below) • -f <list> comma separated list of filters (see list of filters below) 8

anonymize • usage: /usr/dirt/src/tcpdpriv-1. 1. 10/tcpdpriv • P 99 – pass TCP port numbers through unchanged • A 60 – map address using mapping file • M 20 – option for multicast addresses 9

Example plot – throughput (Mbps) • A 10 -min trace collected at low-usage time (2: 30 am) 10

Example plot – throughput (Kpps) 11

Analysis ØSimple statistics like throughput plots over time ØLoss rates ØRTT (round trip time) calculations ØRunning tmix experiments with the data Øanalyze results Øcreate various possible scenarios and test (e. g. what does doubling the traffic throughput do to end user response times? ) 12

Network Topology Monitors Ethernet Switch Router End systems Router Access router & control station arp proxy … … Ethernet Switch End systems NFS servers 13

Tmix discussion • Replay trace on the network in a controlled environment • Throughput can be varied up or down • Induce losses and delays per flow • Replaying a-b-t sequences 14