Summary: User-level Internet Path Diagnosis
Ratul Mahajan Neil Spring David Wetherall Thomas Anderson
University of Washington
Diagnosing faults in the Internet is arduous and time-consuming,
in part because the network is composed of diverse components
spread across many administrative domains. We consider an ex-
treme form of this problem: can end users, with no special privi-
leges, identify and pinpoint faults inside the network that degrade
the performance of their applications? To answer this question,
we present both an architecture for user-level Internet path diag-
nosis and a practical tool to diagnose paths in the current Internet.
Our architecture requires only a small amount of network support,
yet it is nearly as complete as analyzing a packet trace collected
at all routers along the path. Our tool, tulip, diagnoses reordering,
loss and significant queuing events by leveraging well deployed but
little exploited router features that approximate our architecture.
Tulip can locate points of reordering and loss to within three hops
and queuing to within four hops on most paths that we measured.
This granularity is comparable to that of a hypothetical network