marcelo bagnulo braun wrote:
My understanding of how such mechanism would work is the following:
The shim layer observes the amount of traffic exchanged during the
last T seconds, being Tx the number of packets transmitted and Rx the
number of packets received during the last T seconds.
If Tx>0 and Rx>0, then no problem
If Tx=0, then no problem
In those two cases it is really "not my problem", since there might be
a problem, but the peer will have to detect it.
If Tx>0 and Rx=0, then perform a reachability test to verify the
current locator pair, and eventually a path exploration exchange
Upon the reception of a path exploration by the peer, the node must
perform a reachability test to verify the current locator pair.
ok
My opinion about these two are the following:
About 1: i guess this mechanism would improve the efficiency of the
solution because it would reduce the number of reachability test
exchanged to verify the current locator pair in the case of and UDP
bidirectional flow (or any other bidirectional flow where the ULP
does not provide positive feedback)
Yes, I think it will reduce the number of probes in this case.
About 2: this mechanism optimizes the case of bidirectional flow that
belongs to ULPs that not provide positive feedback (e.g. UDP)
However, this mechanism only work in the case where at least one path
with bidirectional connectivity is available. This mechanism fails in
the case where the only paths available are two different
unidirectional paths. This means, that if we want to support such
case (i.e. if we want to be able to preserve the communication in
this case), then we need to be able to detect and overrule such case.
I don't understand why you think this is limited to the bidirectional
locator pair case. If A is using <A1, B1> and B is using <B2, A1>,
then the optimization to suppress probes works just as well as when B
is using <B2, A1>. The probes just serve to verify the current locator
pair, hence the response to a probe would presumably use the current
locator pair in the reverse direction.