System Diagnostic Tool NDT Duplex-Mismatch recognition overhaul

Presentation Transcript

Arrange Diagnostic Tool (NDT) Duplex-Mismatch recognition refresh Fall Member Meeting Sept 21 , 2005 Rich Carlson RCarlson@internet2.edu

Motivation for work Measure execution to clients desktop Identify genuine issues for genuine clients Network foundation is the issue Host tuning issues are the issue Make apparatus easy to utilize and comprehend Make instrument helpful for clients and system managers

Mismatches can happen anyplace

Building Wire Building Switch Desktop Laptop PC Typical Campus framework Desktop/Laptop PC interfaces with building switch by means of (feline 5 curved combine link). Different hosts Uplink to grounds spine Other hosts

Ethernet transmission system Half Duplex Use bearer sense flag to figure out whether interface being used If not, send outline at head of line Else, sit tight for edge to end and send outline Use impact identification flag to figure out whether other station additionally sends Full Duplex Send parcel at head of line Disable transporter sense Disable crash discovery

Duplex Mismatch Detection Condition exists because of arrangement blunder User "Knows" full duplex is speedier than half duplex Administrator 'keeps issues' by settling switch Developing systematic model to portray how organize works Expanding model to depict UDP and TCP streams Test models in LAN, MAN, and WAN situations NIH/NLM give subsidizing

NDT Srv NDT Clt 100 Mbps Full Duplex 100 Mbps Mismatch Switch Receiver Source Test condition Receiver is put is different states Switch = full & Host = full or half Switch = half & Host = full or half Data Packets Ack Packets

Results for TCP streams Source is Full and Destination is Half Data bundles lost Ack parcels postponed or lost Expect poor execution because of vast number of retransmissions Source is Half and Destination if Full Data parcels deferred or lost Ack parcels lost Expect poor execution with substantial number of copy acks

Analytical Loss-Model Loss versus Transmission rate

TCP Operation on LAN Observed conduct relies on upon course of TCP stream and course of crisscross Losing ACKs has greater impact than losing Data parcels

FD HD-FD HD-HD Four Cases of Duplex Setting

Duplex Mismatch Switch is Full & Host is Half

Tentative Mismatch Detection Full to Half confuse location Large rate of copy ACKs Connection invests dominant part of the energy in CwndLimited state

Duplex Mismatch Switch is Half & Host is Full

Tentative Mismatch Detection Half to Full confound recognition Large number of timeouts causes long sit without moving time (RTO x timeout esteem) Connection invests larger part of the time in CwndLimited state

Next Steps Test proposed recognition calculations in LAN, MAN, and WAN conditions Test proposed recognition calculations with various customers (Windows, Mac, *nix) Refine apparatus to report conceivable/plausible issues

Availability Open Source Development extend http://www.sourceforge.net/ventures/ndt Tools accessible by means of from http://e2epi.internet2.edu/ndt/download.html Contains source code Email examination list ndt-users@internet2.edu Goto http://e2epi.internet2.edu/ndt site and snap ndt-clients – General discourse on NDT instrument ndt-declare – Announcements on new components