This will allow for configuration of some of the timers by the user,
and allow him to inspect current values being used.
It will be also useful for TTCN3 tests which may want to test some of
the timers without having to wait for lots of time.
Timers are splitted into 2 groups: BTS controlled ones and PCU controlled
ones. The BTS controlled ones are read-only by the user (hence no
"timer" VTY command is provided to change them).
TbfTest.err output changes due to timers being set up correctly as a
consequence of changes. Other application such as pcu_emu.cpp and
pcu_main.cpp had to previosuly set the initial values by hand (and did
so), but apparently TbfTest.c was missing that part, which is now fixed
for free.
Depends: libosmocore.git Id56a1226d724a374f04231df85fe5b49ffd2c43c
Change-Id: I5cfb9ef01706124be262d4536617b9edb4601dd5
Since [1], OsmoPCU already starts to retransmit downlink blocks before
the MS has had a chance to receive them and/or send the related
acknowledgement in uplink. Make this optional with the new VTY option
"no dl-tbf-preemptive-retransmission".
[1] e25b5b91f6 ("tbf: Only create dummy frames if necessary")
Related: OS#2408
Change-Id: Id08aed513d4033aa0d4324c6ce07cbb2852f2f92
In 3GPP TS 44.060 the selection of MCS for retransmissions is defined as
separate tables (8.1.1.1 and 8.1.1.2) depending on the value of
resegmentation bit (which is opposite to the way EGPRS_ARQ are defined
in the source code). Let's follow the same idea and explicitly check for
resegmentation bit value and use separate tables. This also makes it
easier to add proper support for special cases (MCS-6-9 and MCS-5-7) and
padding in future independently for different ARQ types. The code is
also moved to c to avoid unnecessary conversions to and from cpp class.
Change-Id: Ia73baeefee7a58834f0fc50e3b8bf8d5e3eb7815
* use enum CodingScheme directly instead of converting it to class and
back
* drop useless mode check
* log errorneous update attempt
Change-Id: I763136c2f356d63aa3d28d09c57fd5faf5336258
In preparation for Channel Coding Command encoder in follow-up patches
let's add necessary helpers. Those are similar to previously used
helpers from GprsCodingScheme class but without CamelCase and with less
typo chances between Gprs and Egprs cases.
Change-Id: I6699cbc8d7ae766fa4d2b3d37e5f9ff1cf158b7e
Move functions which compute number of blocks or bits depending on
header type and corresponding enum outside of GprsCodingScheme
class. This will allows us to use standard libosmocore value_sting
functions in upcoming patches for IA Rest Octet encoding/decoding.
Change-Id: Id0873f85e1f16a72e17e7fbc4ad76b194917067f
Move generic MCS enum to C header file to simplify further modifications
to GprsCodingScheme class in follow-up patches. This also allows us
to use standard libosmocore value_sting functions in upcoming patches
for IA Rest Octet encoding/decoding.
Related: OS#3014
Change-Id: I993b49d9a82b8c7ad677d52d11003794aeabe117
* store N310* counters in shared array similar to corresponding timers
* add functions to increment/reset counters
This avoids direct access to TBF counters from PDCH.
Change-Id: I8ffff9c7186f74bde7e6ac5f6e98f0b3e4c35274
Related: OS#1539
Many files include unnecessary headers and don't include headers which
are actually used. Because of that combined with the fact that OsmoPCU
is a mixture of C and C++, it makes it hard to modularize code. Fix
this (using iwyu [1] tool):
* add missing headers
* remove unused headers
[1] https://include-what-you-use.org/
Related: OS#1539
Change-Id: I8c9f488a43b099c72b2d30d3245e7ba50872fc00
* add function to set/unset given assignment type
* log assignment type flag changes
* update tests output with additional logs
This enables us to carefully track the TBF assignment type transitions.
Change-Id: I3fe9d52472be8b7f257e8326b2f84e8e7d7bd1f4
Related: OS#1759
* drop unused parameters (from both functions and structs)
* document used parameters and return values
* tighten types used for parameters
* use consistent formatting
Tests are adjusted accordingly but test results are left untouched to
avoid regressions.
Change-Id: I39d81ab64ff790b9c4c2d0312a574485cd83e755
Related: OS#2282
* add functions/macros for setting TBF's poll state
* add function for checking TBF's poll state
Change-Id: I6db1c4e7bd0a49aeb5e391afe371c36b96c6a702
Related: OS#1539
* add functions/macros for setting TBF's UL/DL state
* add functions for checking TBF's UL/DL state
* move pre-free check into separate function
N. B: this should not be confused with TBF-UL or TBF-DL state.
Change-Id: Idcbf5775d17b1247f2ed01788f9b0788ce66e871
Related: OS#1539
Previously all TBF-related events were logged as part of DRLCMAC which
is too broad to make it practically useful due to excessive amount of
log messages generated. Introduce dedicated log categories for
TBF-related events. Adjust test output as necessary.
Change-Id: I64d660e5971263d5c63d2ba95d50625c16a594aa
We use the same approach for osmo_fsm: when state transition happens,
it's not very useful to always log the transition function itself, it's
much more useful to see where the actual transition comes from.
Change-Id: I348ba89bdda2b44c7019e9c893c764ee08c80bec
Related: OS#1759
Move actual calculation into shared function and use it to set window
size for TBF. TBT test output requires cosmetic adjuestements due to
extended debug output.
Change-Id: Ib9f4a277082da3c71007f5f3b4f2acac8b994540
Related: OS#1759
The UL and DL TBF use different classes implementing window
management. Hence it's better to use it explicitly instead of using the
common window management superclass inside common TBF superclass. While
at it, also remove the direct access to window class - use accessor
functions instead.
Related: OS#1759
Change-Id: I0b55aa8947db65f7206adcf53ea32b74a831d9e6
* introduce generic function to check whether particular flag was set
for'a TBF and clear it if necessary. Use this instead of
clear_poll_timeout_flag()
* add function to explicitly set assignment and appropriate state flags
Overall this makes the code easier to read and debug.
Related: OS#1759
Change-Id: Ic4560280c72f91700f2e19c6c7f6658dc29625c2
* use appropriate types for coding scheme parameters
* add comment regarding possible number of RLCMAC blocks
The code in create_dl_acked_block() has underlying assumption that
rlc.num_data_blocks can never be more than 2, which is true and is
enforced by appropriate asserts but is not obvious when looking at the
function code alone. It's equally hard for Coverity which leads to false
positives in scan.
Lets' make this assumption explicit by putting it into for(;;) condition
alongside with corresponding comment.
Fixes: CID143070
Change-Id: If599a6c8a6ef56d847604fcf41bb71decccd8a78
When troubleshooting TBF timers we're not only interested in timer
duration but also in the code which triggered it. Let's use LOGPSRC to
log it: wrap t_start() in a macro for convenience.
Change-Id: If5f883ae52c469e5158bad24da9904fdc455582f
Related: OS#2407
Use generic timer handling infrastracture to handle assignment/reject
internal timer. Rename timer array accordingly. Use defines with
explicit second/microsecond values to make it more readable.
Change-Id: I63fb7e6f0695383a83472c836a381a055f64690b
Previously TBF got single timer so the pending timer was automatically
cancelled when new one was scheduled. Let's make it more robust by
implementing independent T31 xx timers from 3GPP TS 44.060 §13.2 with
corresponding start/stop functions and counters.
The semantics of the timers is preserved as before: pending timers are
restarted unconditionally. It might be neecessary to change this later on
after spec review.
N. B. T0: used for assign/reject timeouts, have to be properly
attributed and documented first.
Change-Id: I0305873ca47534f53441247217881da59625e1f7
Related: OS#2407
When troubleshooting complex issues with TBF lifecycle, it's much easier
to follow the logs which are consistently formatted. Add LOGTBF*() macro
similar to struct-specific log routines we use in other Osmocom project
and use it to log TBF-related messages in a unified way. Tweak test
output accordingly.
Related: OS#2407
Change-Id: I388249afefc32d2f6e5cb5e5abc6daf4dbd284ea
* log timer values
* log start/stop cause
* update test output as necessary
This simplifies debugging issues with TBF timers.
Related: OS#2407
Change-Id: Ib8e537416af9bec5d447356286f44e9e8bbf1b7a
We do not use this style (#warning as an issue tracker replacement) in
any other Osmocom project. Also those warnings clutter compiler output
making it harder to spot warnings for the actual code.
Change-Id: I72070e2a027e60e8b80c12ccfa23ff075434689f
* introduce enum describing poll kind and use it in set_polling()
* move state change into set_polling()
* move logging into set_polling() and unify output
* move duplicated code into static function
* adjust tests to match unified logging output
Change-Id: I14074207f8bbc18b3ebd60875bb99a0a3a4b399d
Related: OS#1524
This function does not really belongs to BTS and it heavily relies on
direct access to TBF-DL members anyway.
Change-Id: I04584103018675a2f35cfb565473bfd81a208d7c
Closes: OS#1540
In commit 9399046729 the lookup by
TLLI, TLLI-OLD and IMSI has been implemented, but the corresponding
compile-time warning was never removed.
Change-Id: I7a1767bc7cab01048e851fd4e63112bc676d6c78
Do not access TBF internals directly from rcv_control*dl_ack_nack() -
wrap corresponding code into TBF-DL method.
Change-Id: I3d1b5782001e45617b4a960612fcfc249904b37c
Related: OS#1539
Solves a sanitizer issue where punct2 is unset when passed to
gprs_rlc_mcs_cps() and thus takes a value not defined in the enum.
Change-Id: I004cbbab15e6ffa2749f4b7f1df651517c2ae693
Adds spb counters at BTS level(show bts statistics).
Adds RLC/MAC downlink control msg at ms level(show ms imsi <imsi_val>).
Adds the number of coding schemes counter for UL at TBF level.
Change-Id: Icbe4ba95e34bea89ee36f532d099db68204b7c38
Adds DL throughput in show ms imsi <imsi_value>.
Adds the number of coding schemes counter and rlc nacked counter at TBf level.
Change-Id: Ia95b0404989b00db0e7ba416bc40d09ef41fde1c
Fix alignment of EPDAN outside the RLC transmit window,
according to section 9.1.8.2.4 in 44.060 version 7.27.0 Release 7.
The specification explains that a bit within the uncompressed bitmap
whose corresponding BSN is not within the transmit window shall be
ignored. Without this fix PCU was dropping the EPDAN message and not
updating the status of BSNs which are inside the RLC window. This patch
updates the status of the BSNs which are inside the window and ignores
the remaining bits.
Related: OS#1789
Change-Id: Id07d178970f168f5389016c1eea31eb6b82057b6
gcc6 is optimizing if (!this) {CODE} as this is assumed to never be a
std::nullptr here. Move the null check to the caller. In preparation of
removing the check within llc_queue->size(), all callers must check the object
before calling it. Make sure of that: make the llc_queue() access function
protected and offer only a public llc_queue_size() function that incorporates
the NULL check. All current callers are only interested in the
llc_queue_size().
Tweaked-by: nhofmeyr
Change-Id: I88cc3180f8f86785e3f07981895dabddf50b60a2
A subsequent patch needs to call this from gprs_rlcmac_tbf::update(),
so to avoid code dup, put the calculation in a separate function.
Related: OS#1808
Change-Id: I7c7777d43f843bbd3421503fc2a8600f148ca035
* initialize with invalid TA instead of making assumption that phone is
located within 550 meters (TA=0)
* only set valid TA
Change-Id: Idfc40ff0c11bdac13d9e28fbfa4e95dfc6b735b0
Related: OS#1526
Modify the EGPRS DL TBF flow to support Split block during
Retx. This patch will also Upgrade the test suite with test cases
to validate the EGPRS Downlink SPB for Retransmission
Scenarios like MCS6->MCS3, MCS4->MCS1, MCS5->MCS2, MCS9->MCS3
MCS7->MCS2, MCS8->MCS3 have been simulated and Integration tested
in NuRAN 1.0 hardware thoroughly.
Change-Id: I242afdd8ae7622dec8593b26382ad66bad5b9516
Modify the existing data structure to support ARQ-II for Retx in EGPRS DL.
This will also hadle compilation issue related to renaming the variable.
Change-Id: I734b1024bb32f2daa43af4adf59f4a17f2294afe
It makes no sense to call functions on null pointer object. Use
the name of the old tbf.
Change-Id: I93b8c07a0b2de40a11e94fd6c212897cbe3b50ef
Reviewed-on: https://gerrit.osmocom.org/212
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
The counter rlc_sent has nothing to do with the TBF.
The RLC packet got sent in the gprs_rlcmac_sched().
Change-Id: I5d2b910ea7cc250f17530406eda3be9b29b051fd
Reviewed-on: https://gerrit.osmocom.org/84
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
Adds support to find the puncturing scheme for retransmission
with MCS change, retransmission with no MCS change, transmission
case. Puncturing scheme selection for retransmission case with
MCS change is aligned with TS 44.060 9.3.2.1. Puncturing scheme
selection for retransmission without MCS change, fresh transmission
is aligned with TS 44.060 10.4.8a.3.1, 10.4.8a.2.1, 10.4.8a.1.1
Currently single BSN blocks of size 68 (a single unit from MCS-8)
are put into a MCS-6 block with padding according to TS 44.060
Annex J. Unfortunately, these packets are ignored by the E71. This
might be related to the currently incorrect usage of the puncturing
schemes and the RSB bit (the puncturing schemes are not updated and
the RBS flag is never set).
Avoid downgrading from MCS-8 to MCS-6 if there is no second block
available. Send the block twice instead.
Sponsored-by: On-Waves ehf
Comparing the coding scheme properties doesn't seem to be strong
enough, since create_dl_acked_block(fn, ts, index, index2) sometimes
had to combine data units of different size this way.
Check the registered size of the BSN blocks instead, since these must
match if two blocks are to be combined in a single RLC data message
with MCS7-9.
It is not yet clear, what exactly goes wrong with the current
implementation, but this commit fixes the problem which trigger the
assertion in create_dl_acked_block.
Sponsored-by: On-Waves ehf
Currently only one BSN block is encoded in each RLC data message,
even if MSC7-9 are used, which transport two independant (except for a
max BSN delta of 512) BSN blocks. In that case, the same block is
just put twice into the same message.
The current create_dl_acked_block(fn, ts) method handles
block selection (resend, new BSN, dummy block, ...) and restart
handling in one method and is too complex to extend it accordingly.
Therefore this commit move the block selection/creation handling into
a new method (take_next_bsn) which delivers the next BSN along with a
hint, whether it may be combined with another block. In that case,
the function can be called a second time (this time with a valid
previous BSN, that's the one returned by the first call) to get the
second BSN. The real block generation method
create_dl_acked_block(fn, ts, index, index2) is then called with both
BSNs as indices (the second must be -1, if there is only one BSN).
Note that every BSN returned by take_next_bsn should be passed to
create_dl_acked_block to avoid state inconsistencies.
Sponsored-by: On-Waves ehf
Currently the method is hard-coded to support a single BSN only.
MCS-7 to MCS-9 encode 2 data blocks into a single RLC data message.
This commit refactors create_dl_acked_block to process any number
of blocks internally.
Note that this does not extend the parameter list accordingly and
just duplicates the BSN if these MCS are being used.
Sponsored-by: On-Waves ehf
The offsets of the data areas change when padding is used (see TS
44.060, 9.3.2.1 and Annex J for details).
Extend the parameter lists to pass the with_padding flag and use
that information to compute the correct offsets.
Sponsored-by: On-Waves ehf
Currently only header type 3 (MCS-1 to MCS-4) is supported.
Add header structs to rlc.h and extend
Encoding::rlc_write_dl_data_header accordingly.
Sponsored-by: On-Waves ehf
Currently the checks for and the actual polling is done in several
places by copy & paste of several lines of code. This hinders changes
of they polling is handled internally and also is likely source of
programming mistakes.
Separate this into a check_polling function, that checks whether
polling is possible and returns the FN and the RRBP to be used in
that case. Otherwise the cause is logged (LOGL_DEBUG) and a negative
error value is returned. There are no other side effect beside the
logging.
If the call is successful, the set_polling method can be used to
actually register the polling.
Extend the encoder functions' parameters lists by an rrbp parameter.
Sponsored-by: On-Waves ehf
Currently tbf->control_ts is used to look up an incoming poll
response. Since that may eventually change, poll timeouts could
theoretically happen in that case.
Store the real poll TS in tbf->poll_ts at all places where
tbf->poll_fn is set. Do not use tbf->control_ts to look up
outstanding polls.
Sponsored-by: On-Waves ehf
Currently there are some places where tbf->control_ts != ts is
evaluated to check, whether ts is a control slot.
Replace these expressions by tbf->is_control_ts(ts) which does
the same whitout exposing internal fields.
Sponsored-by: On-Waves ehf
Currently the is a release() function which takes care of
statistics and shutdown of properly finished TBFs, but which
cannot be used for aborted TBFs.
This commit add an abort() method which handles unacked RLC blocks
as lost and doesn't start a release timer. This method will be
invoked by tbf_free() for downlink TBF.
Sponsored-by: On-Waves ehf
Currently the values in the BSSGP RA Cap IE are eventually use
overwrite the 'good' values obtained from the MS earlier.
Use the 'good' values when the are present, which is assumed if
at least one of ms->ms_class() or ms->egprs_ms_class() is set.
Sponsored-by: On-Waves ehf
The bitvec RBB is always valid, even when FINAL_ACK_INDICATION is
set. This is done by the ack/nack decoder function which fake a
bitmap starting with V(A) up to V(S)-1 in that case (see
Decoding::handle_final_ack).
Call gprs_rlcmac_dl_tbf::update_window unconditionally and only use
is_final for logging and TBF state changes in
gprs_rlcmac_dl_tbf::rcvd_dl_ack.
Sponsored-by: On-Waves ehf
The current methods are based on the GRPS specific RBB and SSN values
and formats which are not compatible with EGPRS.
Add a second set of similar methods with the same semantics but
which are based on a bitvec and the first BSN instead.
The following methods are affected:
- gprs_rlc_dl_window::update
- gprs_rlcmac_dl_tbf::rcvd_dl_ack
- gprs_rlcmac_dl_tbf::update_window
Sponsored-by: On-Waves ehf
The MS' RLC receiver needs a valid CPS field to decode the block.
Add the function gprs_rlc_mcs_cps to generate the CPS value based on
coding scheme, puncturing, and padding.
Sponsored-by: On-Waves ehf
Currently the GPRS data block encoding is applied to every
coding scheme, even if an MCS is selected.
This commit renames the actual encoding function to
rlc_data_to_dl_append_gprs (not exported) and puts
selection code into Encoding::rlc_data_to_dl_append. This
requires an additional cs argument.
Sponsored-by: On-Waves ehf
Currently TBF related tasks (status changes, counter updates,
LLC dummy command insertion) as well as
RLC data block generation are done within create_new_bsn.
The data block creation part has already been copied to
the stateless Encoding::rlc_data_to_dl_append function.
This commit changes create_new_bsn to use the encoder function and
just care about the TBF related stuff.
Since the rlc_data_to_dl_append function has been validated against
the test cases being described in annex B of TS 44.060, this
commit fixes an encoder bug which leads to broken LLC frames in
a special case (see example B.2, the main header's E bit was
erroneously set to 1 in that case). When this happens, the LLC frame
will get discarded after reassembly, so that TCP will have to
retransmit the lost packet.
Sponsored-by: On-Waves ehf
This commit removes the use of struct rlc_dl_header from
gprs_rlcmac_dl_tbf::create_dl_acked_block and
gprs_rlcmac_dl_tbf::create_new_bsn. Instead of patching the
data area directly, the RLC block encoding functions are used.
Note that the data unit encoding is still hard-coded to GPRS in
create_new_bsn, so using MCS 1-4 (albeit being supported by the
encoder) will not work yet.
Sponsored-by: On-Waves ehf
Currently the RLC message length that is obtained from the DSP is
reduced by 1 if the last byte of the buffer includes spare bits.
While this worked well with GPRS, these bits are being used to
encode RLC blocks in EGPRS mode. Thus this last byte must not be
chopped off. The functionality of the code is not affected by this,
since the modified length value is not used.
This commit adds GprsCodingScheme::usedSizeDL/UL to return
the number of bytes needed to encode the message block. If there are
single bits at the end that are to be used (EGPRS), the functions
return the number of full bytes plus 1 (which is the buffer size
reported by the DSP and returned by sizeUL/sizeDL). The commit also
removes the len parameter from rcv_data_block_acknowledged.
Sponsored-by: On-Waves ehf
The EGPRS multi-slot class need to be parsed from the CSN.1 RA
capability (see gprs_bssgp_pcu_rx_dl_ud).
This commit adds a workaround to get the EGPRS MS class from the MS
object if that is present.
Sponsored-by: On-Waves ehf
Currently the TBF and MS object use a plain integer value
(current_cs) to manage the coding scheme. This makes it difficult to
support the MCS schemes. GprsCodingScheme supports a partial ordering
of these values (CS and MCS) and provides safe increment and
decrement methods.
Use the GprsCodingScheme type instead of integer for cs fields and
variables. Add a 'mode' to GprsMs which can be set to either GPRS,
EGPRS, or EGPRS_GMSK which also set the initial values of
current_cs_ul/dl. Select the mode based on max_mcs_ul and max_mcs_dl.
Sponsored-by: On-Waves ehf
Currently there is only a mod_sns() method which is being used in
expression like bsn_expr & win.mod_sns(). This only works, because
it is known that mod_sns() is (sns() - 1) where sns() in turn is
always 2^n. This is error prone, hard to read, and relies on window
specifics that should be kept inside the respective module.
This commit adds a mod_sns(uint bsn) method to gprs_rlc_ul_window and
gprs_rlc_dl_window, that encapsulates and hides this optimized
computation.
Sponsored-by: On-Waves ehf
Currently the coding scene is stored as number N, where there scheme
is CS-N.
This commit replaces this by a GprsCodingScheme type cs value. The
gprs_rlcmac_cs table is no longer needed and thus removed.
Sponsored-by: On-Waves ehf
The multislot (MS) class and the EGPRS MS class can also be passed
via BSSGP in an MS Radio Access Capability element which can
optionally be contained in a DL-UNITDATA PDU. While this case is fully
supported for GPRS, the EGPRS MS class in BSSGP messages is ignored.
This commit extends gprs_rlcmac_dl_tbf::handle to pass the EGPRS MS
class, too.
Note, that the EGPRS class is not yet taken from the CSN.1 RA
capability and is always set to 0. Note also, that append_data
still uses ms_class only.
Sponsored-by: On-Waves ehf
The leak rate sent to the SGSN does not reflect the current CS level,
lost frames, and control message overhead. So the SGSN cannot do
proper queue control under non-optimal conditions.
This commit computes the leak rate for the last flow control interval
by computing the maximum theoretical leak rate and basically
substracting control blocks, nacked blocks, and reduced block sizes
due to CS downgrade. By using this approach, the value will by more
stable on low load, where the value will tend to be near the value
derived from the configuration. On full load the transmitted value is
completely derived from the measurements.
Note that the MS default values are no adapted to the adapted BVC
leak rate, since a single MS which has a lower link quality would
otherwise be reducing the rate of another MS with good radio
conditions, which would not make much sense if they did not share any
PDCH.
Sponsored-by: On-Waves ehf
Currently reuse_tbf (partly) resets the old DL TBF and uses its PACCH
to establish a new DL TBF. The method can not be used with UL TBFs.
This commit replaces the reuse_tbf method into a
gprs_rlcmac_dl_tbf:release method which triggers the TBF's timer
based deletion (so that the TFI is still reserved for some time) and
a gprs_rlcmac_tbf::establish_dl_tbf_on_pacch which can establish DL
TBFs on existing PACCHs of either DL or UL TBFs.
Sponsored-by: On-Waves ehf
This commit adds the relevant frame number to the "poll timeout"
logging message. In addition, logging is added to the places where
poll_fn gets set.
The goal is to track down the source for frequent "poll timeout"
messages.
Sponsored-by: On-Waves ehf
While this does not happen in real use, and unset btcx can lead to
segfaults in test cases. The other code outside of gprs_bssgp_pcu.cpp
does not depend on bctx being non-NULL:
Sponsored-by: On-Waves ehf
Currently the merging of the meta information (MS class, IMSI) takes
place in gprs_rlcmac_tbf::merge_and_clear_ms(). This makes it
difficult to merge the internal state and does not directly relate to
TBFs anyway.
This commit moves this into a new method GprsMs::merge_old_ms.
Sponsored-by: On-Waves ehf
The confirm_tlli method does not handle TLLI clashes in the MS
storage.
This commit changes gprs_rlcmac_dl_tbf::handle() to use update_ms
instead.
Sponsored-by: On-Waves ehf
When doing an RA Update the network can request to change the TLLI.
In this case, there can be 2 MS objects with different TLLI for a
single real MS. The first is associated with the old TLLI and the
IMSI, while the second is associated with the new TLLI and no IMSI if
it had been created for the uplink TBF. When the first message with
the new TLLI and the IMSI arrives from the network, the PCU is able
to detect this.
Currently this is not handled properly. The TBFs of the old MS object
are not cleaned up properly, keeping the old MS from being deleted.
This patch modifies gprs_rlcmac_dl_tbf::handle to check for this and
if neccessary to move an existing DL TBF and to clean up the old MS
object to ensure its deletion.
Sponsored-by: On-Waves ehf
Currently when receiving a PACKET DL ACK/NACK message with the Final
Ack Indicator bit set, the TBF's state is set to
GPRS_RLCMAC_WAIT_RELEASE but T3193 is only started when the LLC queue is
empty. Otherwise the reuse_tbf() method is called to establish a new
DL TBF. In that case, the timer is not started. This will leave the
current TBF without a timer so it is potentially not released later
on.
This is recognisable by sticky entries in the output of the
'show tbf all' command and possibly allocation failures if there are
too many of them.
This commit changes the code to always start T3193 to make sure, that
a timer is always active when the the state is set to
GPRS_RLCMAC_WAIT_RELEASE.
Note that TS 44.060, 9.3.2.6 requests to release the 'old' TBF
immediately in some cases, which is not implemented by this change.
This will lead to a longer reservation period of the TFI only, which
is safer than reassigning it too early.
Sponsored-by: On-Waves ehf
Currently packets are only dropped if they have reached their maximum
life time. This leads to LLC queues being constantly filled under
load, increasing the latency up to the maximum life time. This kind
of bufferbloat hinders TCP's congestion avoidance algorithms. To keep
the queues short, the CoDel active queue management algorithm can be
used.
This commit changes to llc_dequeue method to apply the CoDel
algorithm to selectively drop LLC frames before they passed to the
TBF layer to be encoded in BSNs. This feature is currently disabled
by default.
The CoDel state is managed per MS since the LLC queues are also kept
in the MS objects.
Note that there is still some buffering in the TBF objects, in the
worst case (CS4) 3.5kByte + LLC-MTU octets are stored there. The
resulting additional packet delay is not (yet) taken into account for
CoDel.
Also note that configuration changes are applied to new MS objects
only.
The following VTY commands are added to the 'pcu' node:
- queue codel activates CoDel, the interval is selected by
the implementation
- queue codel interval <1-1000>
activates CoDel with a fixed interval given
in centiseconds (10ms-10s)
- no queue codel deactivates CoDel
Which interval value to use is still an open issue. For high speed
links (e.g. Ethernet), CoDel suggests 100ms. For slower links, the
expected RTT is recommended. The current implementation uses a
default value of 2000ms.
Measurements:
Note that the following measurements depend on several other factors,
most notably the interaction with the SGSN's flow control. They are
just examples to give an idea how CoDel might influence some
parameters.
The measurements have been done with a single E71, first with a
running ping only (Idle), then with an additional TCP download
of a 360k file (Busy). The CoDel interval was set to 1s.
- Idle :
ping ~400ms, avg queue delay 0ms, dropped 0
- Busy, No CoDel:
ping ~6s, avg queue delay 4-6s,
dropped 0, scheduled 948, duration 54s
- Busy, CoDel:
ping 500-1500ms, avg queue delay ~600ms,
dropped 77, scheduled 1040, duration 60s
More measurements with two MS downloading in parallel (two
independant measurements per case).
- Busy, No CoDel:
dropped 0, scheduled 1883, duration 121s
dropped 19, scheduled 2003, duration 133s
- Busy, CoDel:
dropped 22, scheduled 1926, duration 116s
dropped 22, scheduled 1955, duration 108s
Sponsored-by: On-Waves ehf
Currently the TFI and the TRX have to be determined before the actual TBF
allocation function is called, passing TFI and TRX number as
parameters. This does fit to TFI reuse for different slots, since
this were tightly coupled with the slot selection.
This commit just moves the TFI selection into the alloc_algorithm
functions. The tfi parameter is removed from the the TFI alloc
functions. The trx parameter is changed into use_trx to optionally
limit the trx selection (same semantics like in tfi_find_free).
Sponsored-by: On-Waves ehf
Since both TBF are based on the same reservation which means that
they should be compatible with respect to the slot usage, and since
the new TBF has not been forced to single slot usage, an update of
the allocation is not necessary now.
This commit removes the call to update() from within reuse_tbf().
Sponsored-by: On-Waves ehf
The call to tbf_alloc_dl_tbf misses the pointer to the GprsMs object
which is already known in that case (tbf_reuse). This leads to a full
reallocation of the PDCH slots, which is possibly incompatible with
the old set of slots. This can result in hanging TCP connections and
TCP connection failures.
This commit replaces the old NULL value by the actual GprsMs object.
Since the set_ms() is also done within the tbf_alloc_dl_tbf method,
that call is removed.
Sponsored-by: On-Waves ehf
Since set_ms() is caled on the new DL TBF, the old DL TBF loses the
reference to the MS object. This will lead to a segfault, when
update() is called in reuse_tbf().
This commit adds an optional GprsMs* parameter to update() and uses it
for the slot allocation.
This fixes a TbfTest crash that would otherwise occur after applying
the next commit.
Sponsored-by: On-Waves ehf
Pau Espin
Oliver Smith
Max
Harald Welte
Neels Hofmeyr