Dissecting Round Trip Time on the Slow Path with a Single Packet Pietro Marchetta, Alessio Botta, Ethan Katz-Bassett, and Antonio Pescape Pam’14

Introduction Round Trip Time (RTT) An RTT sample => difficult to interpret RTT values or tease apart the contributing factors. Two possibilities traceroute TTL-limited probe and ICMP Time Exceeded reply Ping an intermediate hop and the destination

Introduction

Dissecting RTT (into two distinct chunks)

Dissecting RTT IP hearder IP Prespecified Timestamp option (TS option) X|ABCD X => destination ABCD => the ordered list of IPs

Dissecting RTT Compliant node W The part of the path Honors the TS option Provides timestamps both on the forward and reverse Ping or traceroute => all nodes D|YDDY =>4 timestamps => compliant node

Dissecting RTT IP options Higher RTT, jitter, packet loss Provide insight into current condition of network links and routers Accuracy Concerns Clock drift

Evaluation

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