linux/net/dccp
Gerrit Renker c8f41d50ad dccp ccid-3: Measuring the packet size s with regard to rfc3448bis-06
rfc3448bis allows three different ways of tracking the packet size `s': 

 1. using the MSS/MPS (at initialisation, 4.2, and in 4.1 (1));
 2. using the average of `s' (in 4.1);
 3. using the maximum of `s' (in 4.2).

Instead of hard-coding a single interpretation of rfc3448bis, this implements
a choice of all three alternatives and suggests the first as default, since it
is the option which is most consistent with other parts of the specification.

The patch further deprecates the update of t_ipi whenever `s' changes. The
gains of doing this are only small since a change of s takes effect at the
next instant X is updated:
 * when the next feedback comes in (within one RTT or less);
 * when the nofeedback timer expires (within at most 4 RTTs).
 
Further, there are complications caused by updating t_ipi whenever s changes:
 * if t_ipi had previously been updated to effect oscillation prevention (4.5),
   then it is impossible to make the same adjustment to t_ipi again, thus
   counter-acting the algorithm;
 * s may be updated any time and a modification of t_ipi depends on the current
   state (e.g. no oscillation prevention is done in the absence of feedback);
 * in rev-06 of rfc3448bis, there are more possible cases, depending on whether
   the sender is in slow-start (t_ipi <= R/W_init), or in congestion-avoidance,
   limited by X_recv or the throughput equation (t_ipi <= t_mbi).

Thus there are side effects of always updating t_ipi as s changes. These may not
be desirable. The only case I can think of where such an update makes sense is
to recompute X_calc when p > 0 and when s changes (not done by this patch).

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
2008-09-04 07:45:42 +02:00
..
ccids dccp ccid-3: Measuring the packet size s with regard to rfc3448bis-06 2008-09-04 07:45:42 +02:00
ackvec.c dccp ccid-2: Separate option parsing from CCID processing 2008-09-04 07:45:37 +02:00
ackvec.h dccp ccid-2: Separate option parsing from CCID processing 2008-09-04 07:45:37 +02:00
ccid.c dccp: Auto-load (when supported) CCID plugins for negotiation 2008-09-04 07:45:31 +02:00
ccid.h dccp: Return-value convention of hc_tx_send_packet() 2008-09-04 07:45:38 +02:00
dccp.h dccp: Clamping RTT values 2008-09-04 07:45:41 +02:00
diag.c dccp ccid-2: Phase out the use of boolean Ack Vector sysctl 2008-09-04 07:45:31 +02:00
feat.c dccp ccid-2: Use feature-negotiation to report Ack Ratio changes 2008-09-04 07:45:32 +02:00
feat.h dccp: Debugging functions for feature negotiation 2008-09-04 07:45:32 +02:00
input.c dccp: Clamping RTT values 2008-09-04 07:45:41 +02:00
ipv4.c dccp: Cleanup routines for feature negotiation 2008-09-04 07:45:26 +02:00
ipv6.c dccp: Cleanup routines for feature negotiation 2008-09-04 07:45:26 +02:00
ipv6.h Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
Kconfig dccp ccid-2: Remove old infrastructure 2008-09-04 07:45:37 +02:00
Makefile dccp: Policy-based packet dequeueing infrastructure 2008-09-04 07:45:39 +02:00
minisocks.c dccp: Fix the adjustments to AWL and SWL 2008-09-04 07:45:35 +02:00
options.c dccp ccid-2: Separate option parsing from CCID processing 2008-09-04 07:45:37 +02:00
output.c dccp: Policy-based packet dequeueing infrastructure 2008-09-04 07:45:39 +02:00
probe.c dccp: Reduce noise in output and convert to ktime_t 2008-09-04 07:45:36 +02:00
proto.c dccp tfrc: Let dccp_tfrc_lib do the sampling work 2008-09-04 07:45:41 +02:00
qpolicy.c dccp qpolicy: Parameter checking of cmsg qpolicy parameters 2008-09-04 07:45:40 +02:00
sysctl.c dccp: Initialisation and type-checking of feature sysctls 2008-09-04 07:45:32 +02:00
timer.c dccp ccid-3: Runtime verification of timer resolution 2008-09-04 07:45:40 +02:00