Bandwidth Estimation in Broadband Access Networks. Venkat Padmanabhan Systems & Networking Group Microsoft Research Joint work with: Karthik Lakshminarayanan (Berkeley) & Jitu Padhye (MSR) June 2004. Outline. Bandwidth estimation Previous work Challenges in broadband access networks
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Systems & Networking Group
Joint work with:
Karthik Lakshminarayanan (Berkeley) & Jitu Padhye (MSR)
Probing rate < available bandwidth ⇒ no trend in OWD
Probing rate > available bandwidth ⇒ increasing OWD
tight & narrow link
di = do⇒ no cross-traffic
di < do⇒ cross-traffic = C*(do-di)/di
Significant per-packet overhead, especially at 54 Mbps
Packet-pair sampling with suitable filtering mostly works
Overestimation due to tendency towards fair share (Pathload)
and differential packet size (Spruce).
Probegap only overestimates slightly under high load.
Overestimation at high loads.
Possible fix: send probes in bunches and pick max OWD.
The single-rate issues persist. But new anomalies with both
Pathload and Spruce due to the burstiness of cross-traffic.
Pathload fails to detect consistent increasing trend even
though probing rate (9.79 Mbps) exceeds avlb bw (6.5 Mbps).
Slight overestimation because of token bucket
Significant overestimation because of token bucket.
Unclear what the right capacity to assume is.