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Troubleshooting Internet Speed Test Issues

Troubleshooting Internet Speed Test Issues

Internet speed testing websites are often used to help determine if the Internet service provider (ISP) is providing the amount of bandwidth you have subscribed to.  If the results of the speed test are unexpected, then there are several steps you can perform to attempt to improve the results.


  • Try using a different Internet speed testing website
  • Connect the computer directly to the Internet connection or modem, bypassing all internetworking equipment, and run the Internet speed test again
  • Enable the RapidRoute “Fast Forwarding Engine” (FFE) on all of the ADTRAN unit's interfaces
  • Make sure there are no errors on the ADTRAN unit’s interfaces
  • Verify the ports are negotiated to the proper speed and duplex
  • Disable Link-layer Discovery Protocol (LLDP) on the interface connected to the Internet or modem

Try Using a Different Website

When an Internet speed test shows unexpected results, the most important step is to try a different speed testing website.  Many of these websites use different variables to determine the upload and download speeds.  Since they are all different, often you will have drastically exaggerated download or upload speeds between different testers.  So, it is recommended to try using multiple sites to obtain an average speed.

Connect Computer Directly to the Internet or Modem

If the computer performing the Internet speed test is going through an ADTRAN unit and/or any other internetworking devices, bypass the units and connect the computer directly into the Internet connection or modem (if the modem is not proving DHCP, you may have to statically assign an IP address to the computer).  With the computer directly connected to the Internet, run the Internet speed test to see if the rates improve.

If the throughput rates are as expected with the computer directly connected to the Internet (bypassing the ADTRAN unit), next reconnect the computer to the ADTRAN unit and follow the steps below.  If the throughput rates are not as expected with the computer directly connected to the Internet or modem, contact the ISP.

RapidRoute (FFE)

Enable FFE on all interfaces (the fast forwarding engine (FFE) is enabled by default, starting in AOS firmware version R10.4.0.)  FFE is enabled on a per-interface basis with the ip ffe command:

(config-eth 0/1)#ip ffe

Interface Errors

On the ADTRAN unit, you should verify:

  • the interfaces do not have any errors
  • the interfaces are negotiated to the proper speed/duplex (typically, the speed and duplex of Ethernet interfaces are 100 Mbps and full-duplex)
  • FFE is enabled on all interfaces

To view the status of the interfaces to check for errors and proper speed/duplex settings, issue the show interface command.

#show interfaces

Displaying interfaces . . .

eth 0/1 is UP, line protocol is UP

  Hardware address is 00:A0:C8:2D:57:06

  ip address is, netmask is

  MTU is 1500 bytes,  BW is 100000 Kbit

100Mb/s, negotiated full-duplex, configured full-duplex

  ARP type: ARPA; ARP timeout is 20 minutes

  5 minute input rate 88 bits/sec, 0 packets/sec

  5 minute output rate 64 bits/sec, 0 packets/sec

    Queueing method: fifo

    Output queue: 0/256/0 (size/max total/drops)

    Interface Shaper: NOT ENABLED

    31184 packets input, 5071001 bytes

    1127 unicasts, 15519 broadcasts, 14538 multicasts input

    361 unknown protocol, 0 symbol errors, 0 discards

    0 input errors, 0 runts, 0 giants

    0 no buffer, 0 overruns, 0 internal receive errors

    0 alignment errors, 0 crc errors

    16035 packets output, 3650729 bytes

    1476 unicasts, 20 broadcasts, 14539 multicasts output

    0 output errors, 0 deferred, 0 discards

    0 single, 0 multiple, 0 late collisions

    0 excessive collisions, 0 underruns

    0 internal transmit errors, 0 carrier sense errors

    0 resets, 0 throttles


You will want to set the ADTRAN to auto on a port so that it will attempt to negotiate the highest speed and duplex with the connected device.  However, the keyword is “negotiate,” so it will expect the peer device to give some notification about its speed/duplex as the link comes up.  Unfortunately, the peer device will not do this unless it is also set to “auto-negotiate.”

Setting the speed to auto negates any duplex setting on the interface and will allow the port to negotiate its speed and duplex. The only time the duplex setting will be enforced is when the speed is hard-set to something other than auto-negotiate.

If the speed is set to auto and the link negotiated to half-duplex, this usually indicates the connected device is hard-set to a speed and duplex, while the ADTRAN unit is configured for auto. You will want to make sure that both sides are either hard-set or are set to negotiate (auto). Otherwise, the links will not negotiate properly and you will experience performance issues and start seeing errors (late collisions; excessive collisions) on the interface.

The term "auto-negotiate" means that you do not have to hard-set a speed/duplex for the Ethernet link to come up, but it will need to negotiate with the connected device to see which speed/duplex to come up on.  For example, say you had ADTRAN1 set to 100/full and ADTRAN2 set to auto-negotiate.  ADTRAN1 will bring the interface up at 100/full, but since it is not attempting to negotiate with ADTRAN2 as ADTRAN2 is expecting, ADTRAN2, according to IEEE specifications, will assume the worst case and come up at 100/half.


Some devices can have problems with the IEEE open standard LLDP (which is enabled on AOS interfaces by default), such as cable modems; therefore, ADTRAN recommends disabling LLDP on the interfaces connected to the Internet or modem.  To disable LLDP on the interface issue the following command on the interface:

(config-eth 0/1)#no lldp send-and-receive

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Last update:
‎05-22-2013 10:35 AM
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