Dissecting Round Trip Time on the Slow Path with a Single

Packet

Pietro Marchetta, Alessio Botta, Ethan Katz-Bassett, and Antonio PescapePam’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

Evaluation

Evaluation

Evaluation

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