kcenon::network::protocols::quic::ecn_tracker Class Reference

ECN (Explicit Congestion Notification) tracker (RFC 9000 Section 13.4, RFC 9002 Section 7.1) More...

#include <ecn_tracker.h>

Collaboration diagram for kcenon::network::protocols::quic::ecn_tracker:

Classes
struct	validation_state
	Internal ECN validation state. More...

Public Member Functions
	ecn_tracker ()
	Default constructor.
auto	process_ecn_counts (const ecn_counts &counts, uint64_t packets_acked, std::chrono::steady_clock::time_point sent_time) -> ecn_result
	Process received ECN counts from an ACK_ECN frame.
auto	is_ecn_capable () const noexcept -> bool
	Check if ECN is validated for use.
auto	is_testing () const noexcept -> bool
	Check if ECN is currently in testing phase.
auto	has_failed () const noexcept -> bool
	Check if ECN has failed validation.
auto	get_ecn_marking () const noexcept -> ecn_marking
	Get ECN marking to use for outgoing packets.
auto	on_packets_sent (uint64_t packet_count) noexcept -> void
	Record packets sent with ECN marking.
auto	last_congestion_sent_time () const noexcept -> std::chrono::steady_clock::time_point
	Get the sent time when the last ECN-CE congestion was detected.
auto	current_counts () const noexcept -> const ecn_counts &
	Get current ECN counts.
auto	reset () noexcept -> void
	Reset ECN tracker to initial state.
auto	disable () noexcept -> void
	Disable ECN tracking.

Private Member Functions
auto	validate_ecn (const ecn_counts &counts, uint64_t packets_acked) -> bool
	Validate ECN capability based on received counts.

Private Attributes
validation_state	state_
	ECN validation state.

Detailed Description

ECN (Explicit Congestion Notification) tracker (RFC 9000 Section 13.4, RFC 9002 Section 7.1)

Tracks ECN feedback from ACK_ECN frames and validates ECN capability. ECN-CE marks indicate congestion without packet loss, providing more responsive congestion detection than loss-based methods.

Definition at line 51 of file ecn_tracker.h.

Constructor & Destructor Documentation

ecn_tracker()

kcenon::network::protocols::quic::ecn_tracker::ecn_tracker

(

)

Default constructor.

Starts in ECN testing mode. ECN capability will be validated when the first ACK with ECN counts is received.

Definition at line 25 of file ecn_tracker.cpp.

    : state_{}
{
    // Start in testing mode
    state_.testing = true;
    state_.capable = false;
    state_.failed = false;
}

References kcenon::network::protocols::quic::ecn_tracker::validation_state::capable, kcenon::network::protocols::quic::ecn_tracker::validation_state::failed, state_, and kcenon::network::protocols::quic::ecn_tracker::validation_state::testing.

Member Function Documentation

current_counts()

auto kcenon::network::protocols::quic::ecn_tracker::current_counts ( ) const -> const ecn_counts&

inlinenodiscardnoexcept

Get current ECN counts.

Returns

Reference to current ECN counts

Definition at line 158 of file ecn_tracker.h.

    {
        return state_.counts;
    }

References kcenon::network::protocols::quic::ecn_tracker::validation_state::counts, and state_.

disable()

auto kcenon::network::protocols::quic::ecn_tracker::disable ( ) -> void

noexcept

Disable ECN tracking.

Called when ECN should be permanently disabled for this connection. After calling this, get_ecn_marking() will return not_ect.

Definition at line 133 of file ecn_tracker.cpp.

{
    state_.failed = true;
    state_.testing = false;
    state_.capable = false;
}

References kcenon::network::protocols::quic::ecn_tracker::validation_state::capable, kcenon::network::protocols::quic::ecn_tracker::validation_state::failed, state_, and kcenon::network::protocols::quic::ecn_tracker::validation_state::testing.

get_ecn_marking()

auto kcenon::network::protocols::quic::ecn_tracker::get_ecn_marking ( ) const -> ecn_marking

inlinenodiscardnoexcept

Get ECN marking to use for outgoing packets.

Returns

ECN marking value to set in IP header

Returns ECT(0) when ECN is capable or testing, returns Not-ECT when ECN has failed.

RFC 9000 Section 13.4.1: ECN-capable QUIC endpoints SHOULD use ECT(0) codepoint.

Definition at line 124 of file ecn_tracker.h.

    {
        if (state_.failed)
        {
            return ecn_marking::not_ect;
        }
        return ecn_marking::ect0;
    }

References kcenon::network::protocols::quic::ect0, kcenon::network::protocols::quic::ecn_tracker::validation_state::failed, kcenon::network::protocols::quic::not_ect, and state_.

has_failed()

auto kcenon::network::protocols::quic::ecn_tracker::has_failed ( ) const -> bool

inlinenodiscardnoexcept

Check if ECN has failed validation.

Returns

True if ECN validation has failed

Definition at line 109 of file ecn_tracker.h.

    {
        return state_.failed;
    }

References kcenon::network::protocols::quic::ecn_tracker::validation_state::failed, and state_.

is_ecn_capable()

auto kcenon::network::protocols::quic::ecn_tracker::is_ecn_capable ( ) const -> bool

inlinenodiscardnoexcept

Check if ECN is validated for use.

Returns

True if ECN capability has been successfully validated

ECN is considered capable when:

• Testing phase is complete
• ECN counts have been successfully validated
• No ECN failure has been detected

Definition at line 91 of file ecn_tracker.h.

    {
        return state_.capable && !state_.testing;
    }

References kcenon::network::protocols::quic::ecn_tracker::validation_state::capable, state_, and kcenon::network::protocols::quic::ecn_tracker::validation_state::testing.

is_testing()

auto kcenon::network::protocols::quic::ecn_tracker::is_testing ( ) const -> bool

inlinenodiscardnoexcept

Check if ECN is currently in testing phase.

Returns

True if still testing ECN capability

Definition at line 100 of file ecn_tracker.h.

    {
        return state_.testing;
    }

References state_, and kcenon::network::protocols::quic::ecn_tracker::validation_state::testing.

last_congestion_sent_time()

auto kcenon::network::protocols::quic::ecn_tracker::last_congestion_sent_time ( ) const -> std::chrono::steady_clock::time_point

inlinenodiscardnoexcept

Get the sent time when the last ECN-CE congestion was detected.

Returns

Time point of the packet that triggered the congestion signal

Used by the congestion controller to determine if we're in recovery.

Definition at line 148 of file ecn_tracker.h.

    {
        return state_.last_congestion_sent_time;
    }

References kcenon::network::protocols::quic::ecn_tracker::validation_state::last_congestion_sent_time, and state_.

on_packets_sent()

auto kcenon::network::protocols::quic::ecn_tracker::on_packets_sent ( uint64_t packet_count ) -> void

noexcept

Record packets sent with ECN marking.

Parameters

packet_count

Number of packets sent with ECN marking

Used for ECN validation to track how many ECN-marked packets have been sent.

Definition at line 119 of file ecn_tracker.cpp.

{
    if (!state_.failed)
    {
        state_.packets_sent_with_ect += packet_count;
    }
}

process_ecn_counts()

auto kcenon::network::protocols::quic::ecn_tracker::process_ecn_counts ( const ecn_counts & counts, uint64_t packets_acked, std::chrono::steady_clock::time_point sent_time ) -> ecn_result

nodiscard

Process received ECN counts from an ACK_ECN frame.

Parameters

counts	ECN counts from the ACK frame
packets_acked	Number of packets acknowledged in this ACK
sent_time	Sent time of the oldest acknowledged packet (for recovery tracking)

Returns

ECN processing result (congestion signal, failure, or none)

This method should be called for every ACK_ECN frame received. It compares the new counts against previously recorded counts to detect ECN-CE increases (congestion signals).

RFC 9000 Section 13.4.2.1: Processing ECN Information

• If ECN-CE count increased, signal congestion to congestion controller
• If ECN counts decreased or don't match expectations, ECN has failed

Definition at line 34 of file ecn_tracker.cpp.

{
    // If ECN has already failed, don't process further
    if (state_.failed)
    {
        return ecn_result::ecn_failure;
    }
 
    // RFC 9000 Section 13.4.2.1: Verify ECN counts are valid
    // ECN counts must be monotonically increasing
    if (counts.ect0 < state_.counts.ect0 ||
        counts.ect1 < state_.counts.ect1 ||
        counts.ecn_ce < state_.counts.ecn_ce)
    {
        // ECN counts decreased - this is invalid, disable ECN
        state_.failed = true;
        state_.testing = false;
        state_.capable = false;
        return ecn_result::ecn_failure;
    }
 
    // Validate ECN if still in testing phase
    if (state_.testing)
    {
        if (!validate_ecn(counts, packets_acked))
        {
            state_.failed = true;
            state_.testing = false;
            state_.capable = false;
            return ecn_result::ecn_failure;
        }
 
        // Check if we have enough data to complete validation
        uint64_t total_marks = counts.ect0 + counts.ect1 + counts.ecn_ce;
        if (total_marks >= validation_state::kValidationThreshold)
        {
            state_.testing = false;
            state_.capable = true;
        }
    }
 
    // Check for ECN-CE increase (congestion signal)
    // RFC 9002 Section 7.1: ECN-CE marks indicate congestion
    ecn_result result = ecn_result::none;
    if (counts.ecn_ce > state_.counts.ecn_ce)
    {
        // ECN-CE count increased - congestion experienced
        result = ecn_result::congestion_signal;
        state_.last_congestion_sent_time = sent_time;
    }
 
    // Update stored counts
    state_.counts = counts;
 
    return result;
}

References kcenon::network::protocols::quic::congestion_signal, kcenon::network::protocols::quic::ecn_failure, and kcenon::network::protocols::quic::none.

reset()

auto kcenon::network::protocols::quic::ecn_tracker::reset ( ) -> void

noexcept

Reset ECN tracker to initial state.

Resets all state including ECN counts and validation status. ECN testing will restart.

Definition at line 127 of file ecn_tracker.cpp.

{
    state_ = validation_state{};
    state_.testing = true;
}

References state_, and kcenon::network::protocols::quic::ecn_tracker::validation_state::testing.

validate_ecn()

auto kcenon::network::protocols::quic::ecn_tracker::validate_ecn ( const ecn_counts & counts, uint64_t packets_acked ) -> bool

nodiscardprivate

Validate ECN capability based on received counts.

Parameters

counts	Received ECN counts
packets_acked	Number of packets acknowledged

Returns

True if validation passed

RFC 9000 Section 13.4.2.1:

• The sum of ECN counts MUST NOT be less than the total number of QUIC packets sent with an ECT codepoint.
• If ECN counts are less than sent packets, ECN is being stripped.

Definition at line 94 of file ecn_tracker.cpp.

{
    // RFC 9000 Section 13.4.2.1:
    // The total increase in ECT(0), ECT(1), and ECN-CE counts MUST be
    // at least the number of newly acknowledged packets that were
    // originally sent with an ECT codepoint.
 
    uint64_t total_increase =
        (counts.ect0 - state_.counts.ect0) +
        (counts.ect1 - state_.counts.ect1) +
        (counts.ecn_ce - state_.counts.ecn_ce);
 
    // We sent packets with ECT(0) marking, so we expect the ECN counts
    // to reflect at least those packets
    if (total_increase < packets_acked && state_.packets_sent_with_ect > 0)
    {
        // ECN counts don't account for all packets - ECN is being stripped
        // by the network path, or the peer doesn't support ECN properly
        return false;
    }
 
    return true;
}

Member Data Documentation

state_

validation_state kcenon::network::protocols::quic::ecn_tracker::state_

private

ECN validation state.

Definition at line 223 of file ecn_tracker.h.

Referenced by current_counts(), disable(), ecn_tracker(), get_ecn_marking(), has_failed(), is_ecn_capable(), is_testing(), last_congestion_sent_time(), and reset().

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The documentation for this class was generated from the following files:

• src/internal/protocols/quic/ecn_tracker.h
• src/protocols/quic/ecn_tracker.cpp