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1335 ARP Issue with Cisco COX Cable Modem

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Good morning Adtran world!

I am having an intermittent (seems to happen about every 2-3 weeks) issue with my client loosing all internet connectivity (Layer 2-7) at what seem to be random times. The "fix" is to reboot the 1335, rebooting just the Cable Modem does not restore service. When this issue happens I do not see any visual (LED lights) off on either piece of equipment and when I do a <sh int> on the WAN interface port I see UP/UP.

My troubleshooting to date has led me to believe that this is an ARP issue based on the attached screenshots and that I can connect my laptop directly to the cable modem and get on the net without a reboot. If I connect the Ethernet cable back to the 1335, using the same cable as I used on my laptop, I still cannot get internet access. A reboot of the 1335 and a few minutes of waiting (usually 3-5) bring services back online.

I ran the debug ARP command during this condition and received a message that I have not come across before ("Packet not enqueued on VLAN 20: Current Pkt Count Exceeded") (see screenshot 1) which may be a buffer filling up issue? I also notice that when this condition is present that I see "(unresolved)" showing up in the MAC Address table for the WAN gateway IP (see screenshot 2).

I am now seeing Input and CRC errors on the WAN interface (see screenshot 3 - CRC Errors) and will return to the site to run a new Shielded Ethernet cable to see if it a "Noise" issue ("Per Cisco - The presence of many CRC errors but not many collisions is an indication of excessive noise.").

Any help with the ARP errors would be greatly appreciated!

Thanks,

Blake

Version info:

MarinaMGMT>sh ver

ADTRAN, Inc. OS version 18.03.01.00.E

  Mainline Version: ENM.11.033

  Checksum: 7B035991

  Built on: Fri Jan 06 14:51:57 2012

  Upgrade key: 0ccbfb7e658e03ef2c41dc7977b80f52

Boot ROM version 15.01.B1

  Checksum: 795D

  Built on: Tue Aug 14 08:53:31 2007

Copyright (c) 1999-2012, ADTRAN, Inc.

Platform: NetVanta 1335, part number 1700515E2

Serial number LBADTN1031AE704

Flash: 33554432 bytes  DRAM: 134217727 bytes

MarinaMGMT uptime is 0 days, 0 hours, 25 minutes, 58 seconds

System returned to ROM by External Hard Reset

Current system image file is "NV1335A-18-03-01-00-E.biz"

Primary boot system image file is "NV1335A-18-03-01-00-E.biz"

Backup boot system image file is "9950515-2A170802.biz"

Primary system configuration file is "startup-config"

WAN Interface (Gig Switchport 0/1)

giga-swx 0/1 is UP, line protocol is UP

  Description: Marina WAN

  Hardware address is 00:A0:C8:62:17:04

  RJ-45 Shielded

  100Mb/s, full-duplex

  input flow control is disabled, 0 pause frames received

  ARP type: ARPA; ARP timeout is 20 minutes

  Last clearing of "show interface" counters: never

  5 minute input rate 289216 bits/sec, 46 packets/sec

  5 minute output rate 71056 bits/sec, 36 packets/sec

    82618 packets input, 85085969 bytes

    74338 unicasts, 8276 broadcasts, 4 multicasts input

    0 unknown protocol, 0 symbol errors, 0 discards

    1706 input errors, 0 runts, 0 giants

    0 no buffer, 0 overruns, 0 internal receive errors

    0 alignment errors, 1595 crc errors

    56499 packets output, 9886701 bytes

    55390 unicasts, 4 broadcasts, 1105 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

WAN VLAN

vlan 20 is UP

  Description: Public IP

  Hardware address is 00:A0:C8:62:16:EB

  vlan 20 Ip address is 72.215.140.35, netmask is 255.255.255.192

  MTU is 1500 bytes, BW is 100000 Kbit

  ARP type: ARPA; ARP timeout is 20 minutes

  IP route-cache express: disabled

  Last clearing of "show interface" counters: never

  5 minute input rate 284592 bits/sec, 45 packets/sec

  5 minute output rate 70048 bits/sec, 35 packets/sec

    80921 packets input, 84166021 bytes

    72654 unicasts, 8267 broadcasts, 0 multicasts input

    3 discards

    55650 packets output, 9654019 bytes

    55643 unicasts, 7 broadcasts, 0 multicasts output

    0 discards

    0 throttles

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Anonymous
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Re: 1335 ARP Issue with Cisco COX Cable Modem

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:

Thank you for asking this question in the support community.  When you get a chance will you reply with the current configuration on the ADTRAN unit (please remember to remove any information that may be sensitive to the organization)?

The ADTRAN's WAN port is hardset to 100/Full.  Typically, cable modems are configured as auto-negotiate for speed/duplex, which would be my guess on this modem, because your PC connected without any problems, and is most likely setup as auto as well.  If the cable modem is set to auto and the ADTRAN is set to 100/Full, then it will negotiate to 100/Half-duplex and could be causing the issues.  Have you tried changing the ADTRAN's port to auto?  The following post will explain this further:  https://supportforums.adtran.com/message/2194#2194

Furthermore, if you haven't already, you should disable LLDP on the ADTRAN's WAN interface, because most cable modems do not support this protocol and sometimes it can cause issues.  The command is no lldp send-and-receive.

The ARP errors you are seeing are most likely a result of the input errors on the interface.  First, I suggest changing the speed/duplex to auto, as well as changing the cable as you mentioned above. 

When you reply with the configuration, I will be happy to review it for you, and hopefully I will be able to provide further insight.

Levi

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New Contributor II

Re: 1335 ARP Issue with Cisco COX Cable Modem

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Hi Blake,

I had an almost identical problem a few weeks ago with an Adtran 1224r and a Cisco DPC 3010 cable modem from Cox. I too was able to get online when plugging a laptop directly into the cable modem but could not get anything when using the Adtran. I also suspected an ARP issue but was unable to reach anyone at Cox that knew what ARP was. The eventual fix was to have Cox replace the cable modem and the issue has not reoccurred since then.

Kris

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New Contributor

Re: 1335 ARP Issue with Cisco COX Cable Modem

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Thanks Kris!

I have had them come out twice now to replace the cable modem and still the same issue. Next step for me is to try to get rid of the CRC and Input errors, guessing either a cable issue (replacing tomorrow morning) or a duplexing issue. The 1335 is set to manual 100/Full and I am not sure what the Cable modem is set to but it is showing an amber light (I think this is 100/Full on that device).

I hope that someone from Adtran can shed some light on the ARP error we are seeing?

Thanks,

Blake

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Anonymous
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Re: 1335 ARP Issue with Cisco COX Cable Modem

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:

Thank you for asking this question in the support community.  When you get a chance will you reply with the current configuration on the ADTRAN unit (please remember to remove any information that may be sensitive to the organization)?

The ADTRAN's WAN port is hardset to 100/Full.  Typically, cable modems are configured as auto-negotiate for speed/duplex, which would be my guess on this modem, because your PC connected without any problems, and is most likely setup as auto as well.  If the cable modem is set to auto and the ADTRAN is set to 100/Full, then it will negotiate to 100/Half-duplex and could be causing the issues.  Have you tried changing the ADTRAN's port to auto?  The following post will explain this further:  https://supportforums.adtran.com/message/2194#2194

Furthermore, if you haven't already, you should disable LLDP on the ADTRAN's WAN interface, because most cable modems do not support this protocol and sometimes it can cause issues.  The command is no lldp send-and-receive.

The ARP errors you are seeing are most likely a result of the input errors on the interface.  First, I suggest changing the speed/duplex to auto, as well as changing the cable as you mentioned above. 

When you reply with the configuration, I will be happy to review it for you, and hopefully I will be able to provide further insight.

Levi

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New Contributor

Re: 1335 ARP Issue with Cisco COX Cable Modem

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Thanks Levi!

I changed it back to Auto and it is now negotiated to 1Gb/s / Full and I do not see the errors anymore. Originally the 1335 was set to Auto but was changed during the last round of troubleshooting to see if the issue was resolved. I also turned off LLDP on the WAN port so hopefully this is the fix and no more outages!

Monitoring on this end for an outage, will reply if it happens again within 1-2 weeks.

Thanks for the assistance.

Blake

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Anonymous
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Re: 1335 ARP Issue with Cisco COX Cable Modem

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Blake:

Have you had any additional trouble with this setup?  Please, let me know if you have any questions.

Levi

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Re: 1335 ARP Issue with Cisco COX Cable Modem

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Thanks Levi!

I have not seen any more errors with this client to date but want to give it a few more weeks to see if it comes back.

MarinaMGMT#sh int gigabit-switchport 0/1

giga-swx 0/1 is UP, line protocol is UP

  Description: Marina WAN

  Hardware address is 00:A0:C8:62:17:04

  RJ-45 Shielded

  1Gb/s, negotiated full-duplex, configured full-duplex

  input flow control is disabled, 0 pause frames received

  ARP type: ARPA; ARP timeout is 20 minutes

  Last clearing of "show interface" counters: 3w 2d 08:38:16

  5 minute input rate 38152 bits/sec, 14 packets/sec

  5 minute output rate 21800 bits/sec, 8 packets/sec

    38476450 packets input, 3728925871 bytes

    0 unicasts, 11104954 broadcasts, 0 multicasts input

    0 unknown protocol, 0 symbol errors, 344 discards

    0 input errors, 0 runts, 0 giants

    0 no buffer, 0 overruns, 0 internal receive errors

    0 alignment errors, 0 crc errors

    22263483 packets output, 617339875 bytes

    4473756 unicasts, 3356 broadcasts, 1009155 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

  L3 Switch

    0 packets input, 0 packets forwarded

    0 header errors, 0 discards

MarinaMGMT#

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Anonymous
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Re: 1335 ARP Issue with Cisco COX Cable Modem

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:

I went ahead and flagged this post as “Assumed Answered.”  If any of the responses on this thread assisted you, please mark them as either Correct or Helpful answers with the applicable buttons.  This will make them visible and help other members of the community find solutions more easily.  If you still need assistance, I would be more than happy to continue working with you on this - just let me know in a reply.

Levi

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Contributor III
Contributor III

Re: 1335 ARP Issue with Cisco COX Cable Modem

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I'm having a similar problem with a 1335 and a Cisco DPC 3010 modem. I will try the LLDP settings to see how it goes.  In this area, any time I connect and Adtran device running a switch port, to a COX cable modem,  It will run for a little while and then quit.  The fix has always been to enable bpdufilter (spanning-tree bpdufilter enable) on the port linking to the cable modem.  This is the first time I've ran into one that just won't link.  The COX support engineers indicate that the cable modem is not seeing any devices.  I noticed that the lldp is still enabled on my configuration so I'm thinking this will most likely correct the issue. 

I usually do turn off LLDP on the cablem modem bound switch port.  I agree with @Levi that this will most likely correct the issue along with getting the speed/duplex settings correct.

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