| Commit message (Collapse) | Author | Age | Files | Lines |
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This fixes the RTO doubling on timeout according to Karn/Partridge.
Exponentially increasing RTO when it times out (e.g. doubling)
fixes the problem that a sudden increase in real RTT starves the sRTT
updates by never getting out of backoff as retransmitted packets can't
update RTT.
Added an parameter to make it less aggressive, default is doubling.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Growing pains.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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This adds the option to use the Round-Trip-Time (RTT) estimation
algorithm as it is implemented in the TCP implementation in Linux. It
looks like it outperforms the TCP default algorithm, so I enabled this
one by default. Also adds the option to change the RTO timeout
calculation to include more (or less) than 4 times the mdev (specified
as a power of 2. Left the default value to 2 (so, 4 mdevs), but 3 (8
mdevs) gives better results in my tests.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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It doesn't really make sense to manually and one-sidedly configure the
timeout of delayed acknowledgements, as setting it too high upsets the
peer's sRTT estimates. Even worse, it also causes a lot of spurious
retransmissions if it exceeds the sRTT mean deviation calculated by
the receiver. Compensating on bare acknowledgment for the ack delay
could improve the RTT estimate deviation, but not the spurious
retransmissions if it was set too high. This sets the delayed ack to
wait for a single RTT mean deviation. Probably needs more tweaking to
further reduce differences between the RTT estimates at the sender and
receiver, e.g. compensate the RTT estimate for delayed acks, or
increase the RTO to add 8 mdevs to sRTT instead of 4. However, it
looks like the mdev estimate is the trickiest one to get to sync, not
the RTT average. Linux reduces the sample weight for mdev from 1/4 to
1/32 in some cases, will give that a shot some day too to see if that
further align sRTT estimates. In any case, this patch already improves
things a lot.
Also fixes a bug where the sender was sending acknowlegments on the
first packets in flight for the 0 sequence number. The receiver
activity was measured in seconds but compared to a timeout value in
nanoseconds.
There's still a lot of spurious retransmissions that start after
actual packet loss occurs, I'm still investigating what causes it.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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The timerwheel was retransmitting packets and the error check for
negative values of the rbuff allocation was instead checking for
non-zero values, causing a buffer allocation to succeed but the
program to continue down the unhappy path leaving that packet stuck in
the buffer unattended.
Also fixes wrongly scheduled retransmissions that cause packet storms.
FRCP is much more stable now. Still needs some work for high
bandwidth-delay products (fast-retransmit).
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Application flows can now be monitored from the RIB, exposing FRCT
statistics (window edges, retransmission timeout, rtt estimate, etc).
Application RIB requires user permissions to be able to access
/dev/fuse.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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The ugent email addresses are shut down, updated to Ouroboros mail
addresses.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Happy New Year, Ouroboros!
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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This adds sending and receiving window updates for flow control. I
used the 8 pad bits as part of the window update field, so it's 24
bits, allowing for ~16 million packets in flight.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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This allows configuring some parameters for FRCP at compile time, such
as default values for Delta-t and configuration of the timerwheel. The
timerwheel will now reschedule when it fails to create a packet,
instead of setting the flow down immediately. Some new things added
are options to store packets for retransmission on the heap, and using
non-blocking calls for retransmission. The defaults do not change the
current behaviour.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Fixes infinite rescheduling with RTO getting lower than the timerwheel
resolution. For very low RTO values we'd need a big packet buffer with
the current memory allocator implementation (rdrbuff). Setting a
(configurable) minimum RTO (250 us) reduces this need.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Ubuntu 16 comes with older versions of OpenSSL, glibc and
libgcrypt. Ouroboros will now fall back to OpenSSL even if the version
is <= 1.1.0.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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This adds a per-message symmetric encryption using the OpenSSL
library. At flow allocation, an Elliptic Curve Diffie-Hellman exchange
is performed to derive a shared secret, which is then hashed using
SHA3-256 to be used as a key for symmetric AES-256 encryption. Each
message on an encrypted flow adds a small crypto header that includes
a random 128-bit Initialization Vector (IV). If the server does not
have OpenSSL enabled, the flow allocation will fail with an -ECRYPT
error.
Future optimizations are to piggyback the public keys on the flow
allocation message, and to enable per-flow encryption that maintains
the context of the encryption over multiple packets and doesn't
require sending IVs.
Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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This allows setting the size of the rbuffs in a system independently
of the main packet buffer using SHM_RBUFF_SIZE. The benefit of setting
a smaller rbuff size is that a single process can't fully occupy the
main packet buffer.
Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>
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Updates the copyright notice in all sources to 2019.
Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>
Signed-off-by: Sander Vrijders <sander.vrijders@ugent.be>
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This splits off the CRC from FRCT so it can be set
independently. Ouroboros now allows raw flows with error checking.
Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>
Signed-off-by: Sander Vrijders <sander.vrijders@ugent.be>
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Happy New Year, Ouroboros.
Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>
Signed-off-by: Sander Vrijders <sander.vrijders@ugent.be>
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This refactors ouroboros to use "program" instead of "application
process" and "process" instead of "application process instance" to
align with current naming in current Operating Systems courses instead
of the ISO nomenclature adopted by RINA. This change permeates through
the entire implementation. Also contains some minor other refactors.
Signed-off-by: Dimitri Staessens <dimitri.staessens@ugent.be>
Signed-off-by: Sander Vrijders <sander.vrijders@ugent.be>
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Multi-block support was forgotten during the update of the build
system. This enables it again and fixes some bugs when it is disabled
and larger SDUs are sent.
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This adds a virtual RIB that is accessible as a filesystem that is
accessed through a fuse mountpoint (configurable , default is
/tmp/ouroboros). Currently, each IPCP will export its link state
database.
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There was an else clause matched with the wrong if statement,
resulting in robust mutexes being enabled even in glibc 2.25.
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This revises the build system to have configuration per system
component. System settings can now be set using cmake.
The standard compliance defines were removed from configuration header
and are set in the sources where needed. Also some small code
refactors, such as moving the data for shims out of the ipcp structure
to the respective shims were performed.
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