[Iccrg] Looking for reviewer for draft-ietf-ledbat-congestion-06
xu at cse.unl.edu
Sun Jun 12 07:53:10 BST 2011
Below are my comments after reading the draft.
**** Section 3.1 ****
First sentence: "a loss occurs [RFC5681], which, in the absence of any
Active Queue Management (AQM) in the network, occurs only when the queue
at the bottleneck link on the end-to-end path overflows "
Since a loss may occur due to link errors, such as fiber errors and
wireless errors, we may change the first sentence to
"... (AQM) and link errors in the network,...."
**** Section 3.3 ****
The data type of each variable is not specified. Since some variables
must be signed variables, it is important to specify the type of each
variable in order to correctly implement the algorithm.
For example, tcp_time_stamp is an unsigned int, so local_timestamp and
remote_timestamp are also unsigned int. But variable
acknowledgement.delay should be a signed int, since
local_timestamp-remote_timestamp may be negative.
**** Section 3.4.2 ****
"a LEDBAT sender stores BASE_HISTORY+1 separate minima- one each for the
last BASE_HISTORY minutes, and one for the running current minute."
But the update_current_delay(delay) code maintains only BASE_HISTORY
minima. So the above sentence should be changed to
"a LEDBAT sender stores BASE_HISTORY separate minima- one each for the
last BASE_HISTORY-1 minutes, and one for the running current minute."
**** Section 3.5 ****
"we recommend that the sender SHOULD use at least 4 samples in each RTT.
Thus, CURRENT_FILTER SHOULD be at least 4, and limited such that no
samples in list are older than an RTT in the
But what if cwnd is less than 4? In this case, there are less than 4
samples in each RTT.
**** General *****
It is not clear what the relation between cwnd and flightsize is. Is
flightsize always the same as cwnd, or could be less than cwnd? When is
flightsize less than cwnd?
On 6/5/2011 12:38 AM, Michael Welzl wrote:
> We're urgently looking for a volunteer to review
> which is currently in Last Call, ending in less than two weeks (15 June).
> If anyone here is willing to do a review, please drop Murari and me a
> note ASAP!
> Iccrg mailing list
> Iccrg at cs.ucl.ac.uk
Lisong Xu, Associate Professor
Computer Science & Engineering
University of Nebraska-Lincoln
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