We investigate the issues in making a delay-based protocol adaptive to heterogeneous
environments. We assess and address the problems a delay-based protocol
faces when competing with a loss-based protocol such as TCP. We investigate if noise
and variability in delay measurements in environments such as cable and ADSL access
networks impact the delay-based protocol behavior significantly. We investigate these
issues in the context of incremental deployment of a new delay-based protocol, PERT.
We propose design modifications to PERT to compete with the TCP flavor SACK.
We show through simulations and real network experiments that, with the proposed
changes, PERT experiences lower drop rates than SACK and leads to lower overall
drop rates with different mixes of PERT and SACK protocols. Delay-based protocols,
being less aggressive, have problems in fully utilizing a highspeed link while operating
alone. We show that a single PERT flow can fully utilize a high-speed, high-delay link.
We performed several experiments with diverse parameters and simulated numerous
scenarios using ns-2. The results from simulations indicate that PERT can adapt
to heterogeneous networks and can operate well in an environment of heterogeneous
protocols and other miscellaneous scenarios like wireless networks (in the presence of channel errors). We also show that proposed changes retain the desirable properties
of PERT such as low loss rates and fairness when operating alone.
To see how the protocol performs with the real-world traffic, the protocol has
also been implemented in the Linux kernel and tested through experiments on live
networks, by measuring the throughput and losses between nodes in our lab at TAMU
and different machines at diverse location across the globe on the planet-lab.
The results from simulations indicate that PERT can compete with TCP in
diverse environments and provides benefits as it is incrementally deployed. Results
from real-network experiments strengthen this claim as PERT shows similar behavior
with the real-world traffic.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/86000 |
| Date | 10 October 2008 |
| Creators | Kotla, Kiran |
| Contributors | A.L, Narasimha Reddy, Bettati, Riccardo |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, born digital |
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