Ping Packets of the STA Are Lost
Common Causes
Packet loss may occur during the ping operation especially when large data packets are specified using the ping -l command.
Common causes are as follows:
- Low signal strength on the radio interface
- Severe interference
- Packet loss, delay, jitter, and broadcast storm on the wired link
- Low terminal performance
Flowchart
Checking Whether Packet Length Affects Ping Operation
During the ping test, use the -1 option to specify packets of different lengths and collect corresponding data.
- Check whether the address www.huawei.com is reachable and set the ICMP packet length to 0 bytes.
C:\Users> ping www.huawei.com -l 0 -n 10 Pinging www.huawei.com [10.82.49.59] with 0 bytes of data: Reply from 10.82.49.59 : bytes=0 time=42ms TTL=249 Reply from 10.82.49.59 : bytes=0 time=30ms TTL=249 Ping statistics for 10.82.49.59: Packets: Sent = 10 , Received = 10 , Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 30ms , Maximum = 42ms , Average = 31ms - Check whether the address www.huawei.com is reachable and set the ICMP packet length to 1000 bytes.
C:\Users> ping www.huawei.com -l 1000 -n 10 Pinging www.huawei.com [10.82.49.59] with 1000 bytes of data: Reply from 10.82.49.59 : bytes=1000 time=43ms TTL=249 Reply from 10.82.49.59 : bytes=1000 time=30ms TTL=249 Ping statistics for 10.82.49.59: Packets: Sent = 10 , Received = 10 , Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 30ms , Maximum = 43ms , Average = 31ms - Check whether the address www.huawei.com is reachable and set the ICMP packet length to 2000 bytes.
C:\Users> ping www.huawei.com -l 2000 -n 10 Pinging www.huawei.com [10.82.49.59] with 2000 bytes of data: Reply from 10.82.49.59 : bytes=2000 time=59ms TTL=249 Reply from 10.82.49.59 : bytes=2000 time=38ms TTL=249 Ping statistics for 10.82.49.59: Packets: Sent = 10 , Received = 10 , Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 35ms , Maximum = 59ms , Average = 40ms
If the packet loss ratio is larger than 5% or the average delay is longer than 500 ms, the terminal has low performance.
Checking Whether Poor Signals Cause Packet Loss
Check whether there is interference affecting the ping operation according to section Signals Are Poor.
Checking Whether Too Many STAs or Low-Rate STAs Degrade the Network Performance
The maximum number of STAs associated with each AP is determined according to actual requirements. If an AP associates with too many users, the WLAN performance degrades, bringing poor user experience.
Additionally, if the terminal NIC supports only the 802.11b mode or the area where the STA is located has weak signals, the association rate between the STA and the AP becomes low. If too many low-rate STAs associate with the AP, the AP performance degrades.
CLI
- Check whether too many STAs are associated with the AP.
Log in to the AC and run the display station assoc-info ap ap-id command.
[Huawei] display station assoc-info ap 5 ------------------------------------------------------------------------------ STA MAC AP-ID RADIO-ID ESS-ID SSID ------------------------------------------------------------------------------ c833-4b6c-9cab 5 0 0 chinaunicom 0c77-1a71-d9dc 5 0 0 chinaunicom c46a-b7ee-85d0 5 0 0 chinaunicom ------------------------------------------------------------------------------
- Check whether too many low-rate STAs are associated with the AP.
Log in to the AP and run the display interface radio radio-id vap vap-id list command in the diagnostic view.
[ap-diagnose] display interface radio 0 vap 0 list ADDR AID CHAN RATE RSSI IDLE TXSEQ RXSEQ SKIP NORML CAPS ACAPS ERP STATE HTCAPS 14cf-9202-13dc 1 1 37M 35 0 19 2416 0 0 ESs 0 f WPM
Web System
- Check whether too many STAs are associated with the AP.
Log in to the web system. Choose Monitoring > User, and check the number of STAs associated with the AP in User List.
- Check whether too many low-rate STAs are associated with the AP.
Repeat 1. In User List, check the negotiation rate between the AP and STAs, and check whether too many low-rate STAs are associated with the AP.
Checking Whether the Wired Network Has Poor Status
Packet loss, delay, jitter, and broadcast storm make WLAN performance deteriorating. You can perform the ping operation to check the link status.
If the ping operation using packets that exceed a certain length fails, check the MTU configuration of the PC.
- Check whether the link between the AP and AC works properly.
Log in to the AC and run the display ap run-info id XX command to check AP's IP address. Ping the AP's IP address using packets of 10, 500, 1000, and 2000 bytes.
# Check whether the host with the IP address 10.1.1.2 is reachable. Set the size of the packet to be sent to 300 bytes and the interval for sending the packets to 3000 ms.
<AC6605> ping -m 3000 -s 300 10.1.1.2 PING 10.1.1.2: 300 data bytes, press CTRL_C to break Reply from 10.1.1.2: bytes=300 Sequence=1 ttl=255 time=31 ms Reply from 10.1.1.2: bytes=300 Sequence=2 ttl=255 time=31 ms Reply from 10.1.1.2: bytes=300 Sequence=3 ttl=255 time=31 ms Reply from 10.1.1.2: bytes=300 Sequence=4 ttl=255 time=31 ms Reply from 10.1.1.2: bytes=300 Sequence=5 ttl=255 time=31 ms --- 10.1.1.2 ping statistics --- 5 packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 31/31/31 msIf the network is unstable or packets are lost on the network, run the tracert command to check the forwarding routes.
# Check the gateways between the local host and the destination address 172.26.0.115.
<AC6605> tracert 172.26.0.115 traceroute to 172.26.0.115 (172.26.0.115), max hops: 30, packet length: 40, press CTRL_C to break 1 10.3.112.1 10 ms 10 ms 10 ms 2 10.32.216.1 19 ms 19 ms 19 ms 3 10.32.216.1 39 ms 19 ms 19 ms 4 10.32.136.23 19 ms 39 ms 39 ms 5 10.32.168.22 20 ms 39 ms 39 ms 6 10.32.197.4 59 ms 119 ms 39 ms 7 10.119.2.5 59 ms 59 ms 39 ms 8 10.140.70.13 80 ms 79 ms 99 ms 9 10.140.71.6 139 ms 139 ms 159 ms 10 10.140.1.7 199 ms 180 ms 300 ms 11 10.140.7.2 300 ms 239 ms 239 ms 12 * * * 13 10.11.4.7 259 ms 499 ms 279 ms 14 * * * 15 * * * 16 * * * 17 * * * 18 172.26.0.115 (172.26.0.115) 339 ms 279 ms 279 ms
Ping the intermediate nodes to locate the fault.
- Check whether broadcast storm occurs on the network.
Log in to the switch on the network and run the reset counters interface GigabitEthernet X/X/X command to clear statistics on the interface. Then, run the display interface GigabitEthernet X/X/X command to check broadcast and multicast packets received on the interface. If the interface receives a large number of broadcast and multicast packets in a short time, the WLAN performance will be degraded.
# Check the broadcast or multicast packets received on the switch interface.
<LSW> reset counters interface GigabitEthernet 0/0/1 Info: Reset successfully. <LSW> system-view Enter system view, return user view with Ctrl+Z. [LSW] display interface GigabitEthernet 0/0/1 GigabitEthernet0/0/1 current state : UP Line protocol current state : UP Description:HUAWEI, AC Series, GigabitEthernet0/0/1 Interface Switch Port, PVID : 150, TPID : 8100(Hex), The Maximum Frame Length is 9216 IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 04bd-70e3-89ff Last physical up time : 2015-11-12 01:38:55 UTC+08:00 Last physical down time : 2015-11-12 01:38:37 UTC+08:00 Current system time: 2015-11-16 22:48:00+08:00 Port Mode: COMMON COPPER Speed : 1000, Loopback: NONE Duplex: FULL, Negotiation: ENABLE Mdi : AUTO Last 300 seconds input rate 480 bits/sec, 0 packets/sec Last 300 seconds output rate 520 bits/sec, 0 packets/sec Input peak rate 17700752 bits/sec,Record time: 2015-11-12 22:06:18Output peak rate 4180056 bits/sec,Record time: 2015-11-13 18:04:52 Input: 88 packets, 11721 bytes Input: 6576 packets, 828691 bytes Unicast: 6135, Multicast: 40 Broadcast: 401, Jumbo: 0 Discard: 0, Total Error: 0 CRC: 0, Giants: 0 Jabbers: 0, Throttles: 0 Runts: 0, Alignments: 0 Symbols: 0, Ignoreds: 0 Frames: 0 Output: 6391 packets, 1165971 bytes Unicast: 6348, Multicast: 24 Broadcast: 19, Jumbo: 0 Discard: 0, Total Error: 0 Collisions: 0, ExcessiveCollisions: 0 Late Collisions: 0, Deferreds: 0 Buffers Purged: 0 Input bandwidth utilization threshold : 100.00% Output bandwidth utilization threshold: 100.00% Input bandwidth utilization : 0.01% Output bandwidth utilization : 0.01% - Check the link between the AC and application server.
Log in to the AC and ping the application server using packets with the size of 10, 500, 1000, and 2000 bytes. The method is the same as that specified in the preceding step.
If the network is unstable or packets are lost on the network, run the tracert command to check the forwarding routes. Then, ping the intermediate devices one by one to rectify the fault. The method is the same as that specified in the preceding step.
- Check device configurations.
To prevent attacks, the network device is configured to discard large data packets or packets that are sent frequently. This may cause a ping operation failure or packet loss. Locate devices on which the ping operation fails.
Fault Troubleshooting
CLI
Perform troubleshooting operations according to the causes:
- Poor signals and severe interference on radio interfaces
Configure RTS/CTS to reduce the impact of interference on packet receiving and sending.
If channels conflict, packet retransmission or loss occurs, resulting in a high packet loss ratio. To prevent this problem, set the RTS/CTS threshold. When the packet length exceeds the threshold, the RTS/CTS function takes effect to reduce the impact of interference on the packets. The configuration is as follows:
# Set the RTS-CTS operation mode to cts-to-self in radio profile.
[AC6605-wlan-radio-prof-2.4g] rts-cts-mode cts-to-self
# Set the RTS/CTS threshold in radio profile 80211b to 1000 bytes.
[AC6605-wlan-radio-prof-2.4g] rts-cts-threshold 1000
- Too many access STAs
Set a proper maximum number of associated STAs for APs, make a proper network planning, and enable load balancing. These operations can prevent AP performance drop caused by too many associated STAs.
# Set the maximum number of associated STAs for APs.
<AC6605> system-view [AC6605] wlan [AC6605-wlan-view] ssid-profile name ssid1 [AC6605-wlan-ssid-prof-ssid1] max-sta-number 50
# Enable load balancing.
- Dynamic load balancing
[AC-wlan-view] rrm-profile name loadbalance-dynamic [AC-wlan-rrm-prof-loadbalance-dynamic] sta-load-balance dynamic enable [AC-wlan-rrm-prof-loadbalance-dynamic] sta-load-balance dynamic start-threshold 15 [AC-wlan-rrm-prof-loadbalance-dynamic] sta-load-balance dynamic gap-threshold 25 [AC-wlan-rrm-prof-loadbalance-dynamic] quit
- Static load balancing
# Create a static load balancing group and set the start threshold for static load balancing to 15 and load difference threshold to 5%.
[AC-wlan-view] sta-load-balance static-group name wlan-static [AC-wlan-sta-lb-static-group-wlan-static] start-threshold 15 [AC-wlan-sta-lb-static-group-wlan-static] gap-threshold 5
# Add AP area_1 and AP area_2 to the static load balancing group.
[AC-wlan-sta-lb-static-group-wlan-static] member ap-name area_1 [AC-wlan-sta-lb-static-group-wlan-static] member ap-name area_2 [AC-wlan-sta-lb-static-group-wlan-static] quit
- Dynamic load balancing
- Too many weak-signal or low-rate STAs
Replan the APs or adjust power of the APs.
To ensure the overall performance of the wireless network, run commands to deny access from low-rate STAs or forcibly disconnect low-rate STAs.
- Restrict access from weak-signal STAs.
Run the uac client-snr enable command to enable the function of restricting access from weak-signal STAs.
By default, the function of restricting access from weak-signal STAs is disabled.
Run the uac client-snr threshold XX command to set the lower threshold for the STA signal strength.
By default, the CAC threshold based on terminal SNR is 20 dB.
[AC6605-wlan-view] rrm-profile name huawei [AC6605-wlan-rrm-prof-huawei] uac client-snr enable [AC6605-wlan-rrm-prof-huawei] uac client-snr threshold 50
- Forcibly disconnect weak-signal or low-rate STAs.
The function of forcibly disconnecting weak-signal STAs is implemented based on smart roaming.
Run the smart-roam enable command to enable smart roaming.
Run the smart-roam roam-threshold check-snr check-rate command to set the trigger mode of smart roaming.
Run the smart-roam roam-threshold snr XX command to set the SNR-based threshold for smart roaming.
Run the smart-roam roam-threshold rate XX command to set the rate-based threshold for smart roaming.
By default, the SNR-based threshold for smart roaming is 20 dB, and the rate-based threshold is 20%.
When the SNR or rate of the associated STAs falls below the threshold, the STAs are forcibly disconnected.
[AC6605-wlan-rrm-prof-huawei] smart-roam enable [AC6605-wlan-rrm-prof-huawei] smart-roam roam-threshold check-snr check-rate [AC-wlan-rrm-prof-smart-roam] smart-roam roam-threshold snr 30 [AC-wlan-rrm-prof-smart-roam] smart-roam roam-threshold rate 30
- Restrict access from weak-signal STAs.
- Low wired network quality
If low wired network quality causes packet loss, troubleshoot the fault using corresponding methods. For example, if a network loop occurs, configure STP or other routing protocols to eliminate the loop.
Web System
- Poor signals and severe interference on air interfaces
Configure RTS/CTS to reduce the impact of interference on packet receiving and sending.
If channels conflict, packet retransmission or loss occurs, resulting in a high packet loss ratio during the ping operation. To prevent this problem, enable the RTS/CTS function and set the RTS/CTS threshold. When the packet length exceeds the threshold, the RTS/CTS function takes effect to reduce the impact of interference on the packets.
Choose Configuration > AP Config > AP Group. Select an AP group and choose Radio Management > Radio 0 > 2G Radio Profile or Radio Management > Radio 1 > 5G Radio Profile. On the radio profile configuration page, set RTS-CTS mode to Cts-to-self and RTS-CTS threshold to 1000, and click Apply.
- Too many associated STAs
Set a proper maximum number of associated STAs for APs, make a proper network planning,and enable load balancing. These operations can prevent AP performance drop caused by too many associated STAs.
# Set the maximum number of associated STAs for APs.
Set the maximum number of STAs in an SSID profile.
#Enable load balancing.
Select Static Load Balancing Group.
Alternatively, set dynamic load balancing parameters in the RRM profile.
- Too many weak-signal or low-rate STAs
# Deny access from weak-signal STAs.
On the RRM profile configuration page, set Restrict access of weak-signal STAs to ON in UAC, and set the Threshold for rejecting access of weak-signal STAs to 20.
#Forcibly disconnect weak-signal STAs.
In Smart Roaming, enable smart roaming, select Based on the SNR and Based on the rate percentage, and set SNR threshold to 20 and Rate percentage threshold to 20%.
- Low wired network quality
If low wired network quality causes packet loss, troubleshoot the fault using corresponding methods. For example, if a network loop occurs, configure STP or other routing protocols to eliminate the loop.
