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VCN: Ignore packet loss detection when there is too few traffic

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When the expected received packet number is smaller than 10, the
packet loss detection result will be ignored because the sample
size is too small to ensure a reliable result.

This patch also fixes the bug where the detector does not update
ths packet loss threshold when carrier config updates

Bug: 332598276
Test: atest FrameworksVcnTests && atest CtsVcnTestCases
Change-Id: Iccc47e83c48699d139029420572e2a2616c357cd
This commit is contained in:
Yan Yan 2024-04-09 01:23:04 +00:00
commit aab9cbd2a5
2 changed files with 31 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

16
Vcn/service-b/src/com/android/server/vcn/routeselection/IpSecPacketLossDetector.java
View file

@ -64,6 +64,12 @@ public class IpSecPacketLossDetector extends NetworkMetricMonitor {
private static final int PACKET_LOSS_PERCENT_UNAVAILABLE = -1;
// Ignore the packet loss detection result if the expected packet number is smaller than 10.
// Solarwinds NPM uses 10 ICMP echos to calculate packet loss rate (as per
// https://thwack.solarwinds.com/products/network-performance-monitor-npm/f/forum/63829/how-is-packet-loss-calculated)
@VisibleForTesting(visibility = Visibility.PRIVATE)
static final int MIN_VALID_EXPECTED_RX_PACKET_NUM = 10;
@Retention(RetentionPolicy.SOURCE)
@IntDef(
prefix = {"PACKET_LOSS_"},
@ -85,6 +91,8 @@ public class IpSecPacketLossDetector extends NetworkMetricMonitor {
* <ul>
* <li>The replay window did not proceed and thus all packets might have been delivered out of
* order
* <li>The expected received packet number is too small and thus the detection result is not
* reliable
* <li>There are unexpected errors
* </ul>
*/
@ -113,7 +121,7 @@ public class IpSecPacketLossDetector extends NetworkMetricMonitor {
private static final int MAX_SEQ_NUM_INCREASE_DEFAULT_DISABLED = -1;
private long mPollIpSecStateIntervalMs;
private final int mPacketLossRatePercentThreshold;
private int mPacketLossRatePercentThreshold;
private int mMaxSeqNumIncreasePerSecond;
@NonNull private final Handler mHandler;
@ -273,6 +281,7 @@ public class IpSecPacketLossDetector extends NetworkMetricMonitor {
mPollIpSecStateIntervalMs = getPollIpSecStateIntervalMs(carrierConfig);
if (Flags.handleSeqNumLeap()) {
mPacketLossRatePercentThreshold = getPacketLossRatePercentThreshold(carrierConfig);
mMaxSeqNumIncreasePerSecond = getMaxSeqNumIncreasePerSecond(carrierConfig);
}
}
@ -476,6 +485,11 @@ public class IpSecPacketLossDetector extends NetworkMetricMonitor {
+ " actualPktCntDiff: "
+ actualPktCntDiff);
if (Flags.handleSeqNumLeap() && expectedPktCntDiff < MIN_VALID_EXPECTED_RX_PACKET_NUM) {
// The sample size is too small to ensure a reliable detection result
return PacketLossCalculationResult.invalid();
}
if (expectedPktCntDiff < 0
|| expectedPktCntDiff == 0
|| actualPktCntDiff < 0

16
Vcn/tests/unit/java/com/android/server/vcn/routeselection/IpSecPacketLossDetectorTest.java
View file

@ -20,6 +20,7 @@ import static android.net.vcn.VcnManager.VCN_NETWORK_SELECTION_IPSEC_PACKET_LOSS
import static android.net.vcn.VcnManager.VCN_NETWORK_SELECTION_MAX_SEQ_NUM_INCREASE_PER_SECOND_KEY;
import static android.net.vcn.VcnManager.VCN_NETWORK_SELECTION_POLL_IPSEC_STATE_INTERVAL_SECONDS_KEY;
import static com.android.server.vcn.routeselection.IpSecPacketLossDetector.MIN_VALID_EXPECTED_RX_PACKET_NUM;
import static com.android.server.vcn.routeselection.IpSecPacketLossDetector.getMaxSeqNumIncreasePerSecond;
import static com.android.server.vcn.util.PersistableBundleUtils.PersistableBundleWrapper;
@ -436,6 +437,21 @@ public class IpSecPacketLossDetectorTest extends NetworkEvaluationTestBase {
mTransformStateInitial, 3000, 2000, 2000, PacketLossCalculationResult.invalid());
}
@Test
public void testGetPacketLossRate_expectedPacketNumTooFew() throws Exception {
final int oldRxNo = 4096;
final int oldPktCnt = 4096;
final int pktCntDiff = MIN_VALID_EXPECTED_RX_PACKET_NUM - 1;
final byte[] bitmapReceiveAll = newReplayBitmap(4096);
final IpSecTransformState oldState =
newTransformState(oldRxNo, oldPktCnt, bitmapReceiveAll);
final IpSecTransformState newState =
newTransformState(oldRxNo + pktCntDiff, oldPktCnt + pktCntDiff, bitmapReceiveAll);
checkGetPacketLossRate(oldState, newState, PacketLossCalculationResult.invalid());
}
@Test
public void testGetPacketLossRate_againstInitialState() throws Exception {
checkGetPacketLossRate(mTransformStateInitial, 7000, 7001, 4096, 0);