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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> |
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| lib | ||
| ccid2.c | ||
| ccid2.h | ||
| ccid3.c | ||
| ccid3.h | ||
| Kconfig | ||
| Makefile | ||