REM: active queue management
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Citations
Receiver-Side TCP Countermeasure to Bufferbloat in Wireless Access Networks
Congestion control, differentiated services, and efficient capacity management through a novel pricing strategy
Active Queue Management Algorithm for TCP Networks with Integral Backstepping and Minimax
On the deterministic approach to active queue management
Receiver-based methods, systems, and computer readable media for controlling tcp sender behavior in mobile communications networks with large buffer sizes
References
Random early detection gateways for congestion avoidance
Rate control for communication networks: shadow prices, proportional fairness and stability
Charging and rate control for elastic traffic
Optimization flow control—I: basic algorithm and convergence
A comparison of mechanisms for improving TCP performance over wireless links
Related Papers (5)
Frequently Asked Questions (17)
Q2. What is the effect of the ECN bit on the packets?
With active queue management, the ECN bit is set to 1 in ns-2 so that packets are probabilistically marked according to RED or REM.
Q3. How many packets are in the REM?
As time increases on the x-axis, the number of sources increases from 20 to 100 and the average window size decreases from 22 packets to 4 packets.
Q4. What is the significance of the exponential form of the marking probability?
The exponential form of the marking probability is critical in a large network where the end-to-end marking probability for a packet that traverses multiple congested links from source to destination depends on the link marking probability at every link in the path.
Q5. What is the price of a queue in RED?
Whereas the congestion measure (queue length) in RED is automatically updated by the buffer process according to Eq. 1, REM explicitly controls the update of its price to bring about its first property.
Q6. What is the end-to-end marking probability of REM?
When the link marking probabilities ml(t) are small, and hence the link prices pl(t) are small, the end-to-end marking probability given by Eq. 5 is approximately proportional to the sum of the link prices in the path:(6)The price adjustment rule given by Eq. 2 or 3 leads to the feature that REM attempts to equalize user rates with network capacity while stabilizing queue length around a target value, possibly zero.
Q7. What is the simplest approach to preventing packet loss?
This involves various interference suppression techniques, and error control and local retransmission algorithms on the wireless links.
Q8. What is the effect of a retransmitter when it detects a loss?
The authors modify NewReno so that it halves its window when it receives a mark or detects a loss through timeout, but retransmits without halving its window when it detects a loss through duplicate acknowledgments.
Q9. What is the end-to-end marking probability of a link?
and only when, individual link marking probability is exponential in its link price, this end-to-end marking probability will be exponentially increasing in the sum of the link prices at all the congested links in its path.
Q10. How many packets are in the ns-2.1b6 simulator?
The simulation is conducted in the ns-2.1b6 simulator for a single link that has a bandwidth capacity of 64 Mb/s and a buffer capacity of 120 packets.
Q11. What is the second approach to reducing packet loss?
The second approach informs the source, using TCP options fields, which losses are due to wireless effects, so that the source will not halve its rate after retransmission.
Q12. What does RED use to determine the marking probability?
Since RED uses queue length to determine the marking probability, this means that the mean queue length must steadily increase as the number of users increases.
Q13. What is the average buffer occupancy in a period t?
Here bl(t) is the aggregate buffer occupancy at queue l in period t and b*l ≥ 0 is target queue length, xl(t) is the aggregate input rate to queue l in period t, and cl(t) is the available bandwidth to queue l in period t.
Q14. What is the value of the queue length in the next period?
The queue length in the next period equals the current queue length plus aggregate input minus output:bl(t + 1) = [bl(t) + xl(t) – cl(t)]+ (1) where [z]+
Q15. What is the marking probability of a packet?
one may choose to measure congestion differently, perhaps by using loss, delay, or queue length (but see the next subsection for caution), but mark with an exponential marking probability function, in order to implement the second, but not the first, feature.
Q16. What is the rate at which the queue length grows when the buffer is nonempty?
When the target queue length b* is nonzero, the authors can bypass the measurement of rate mismatch xl(t) – cl(t) in the price update, Eq. 2. Notice that xl(t) – cl(t) is the rate at which the queue length grows when the buffer is nonempty.
Q17. What is the weighted sum of the queue length in the next period?
The weighted sum is positive when either the input rate exceeds the link capacity or there is excess backlog to be cleared, and negative otherwise.