Cisco 3850X switch randomly stops pinging my voice gateway

[msomerville99]

I am lost at what my issue can be.   I have vonage phones that need to access their Adtran gateway for DHCP and to register in the cloud.  The phones are connected to user switches.  The user switches connect to my C3850X core switch.   The Core switch then connects to the Adtran gateway on the same vlan of the phones.  For some reason, day after day around the same time the switch can no longer ping the adtran gateway so all the phones unregister themselves as they can no longer get to my gateway.  If I shut/no shut the port on the switch, the switch and adtran start communicating again.  This will happen day after day and then it wont happen for several days.   The only vlan allowed to talk between the switch and the adtran is the voice vlan.   Can anyone shed any light on what might be causing this drop in communciation.  There is no error on the switch ports and I have already replaced cabling.  What puzzles me is that it randomly happens.

[Mark Malone]

issue could be on the Adtran side have you checked that device its logs and restarting the port kicks off the connection again , cpu mem etc all good on teh switch around that time it fails ? , what about running an ip sla continuous ping to the Adtran ip keep interesting traffic constantly going to it would it still fail then , it may keep it up

[msomerville99]

Everything on the switch seems to be fine.  I don't have access to the Adtran but every time Vonage looks at it they do not see anything on their side but unfortunately I don't know what they are looking at.  This is how the switch is configured on my side.

interface GigabitEthernet1/0/5
 description Vonage Adtran
 switchport access vlan 100
 switchport mode access
 auto qos trust
 spanning-tree portfast

!

On their connection side, the interface is set to ip address 172.16.100.1 which is the voice subnet (vlan 100).   

Could I have a spanning-tree issue somewhere in my network causing this?  It does not seem likely but that is the only other thing that I can think of.  

[Mark Malone]

This will tell you if you have an STP issue constantly occurring , it will show last change and from where , sounds as if communication is breaking down between the switch and Adtran somehow , personally I would wireshark each side as its working then non working and compare the 2 but I had an issue like this with a modem before and the ip sla keep it active and up as a quick fix
Is the interface clean of errors and drops ?

show spanning-tree detail | inc ieee|occurr|from|is exec

[msomerville99]

This is what the spanning tree command shows:

Switch#show spanning-tree detail | inc ieee|occurr|from|is exec
  Number of topology changes 198 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 51 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 177 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 133 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 110 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 123 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 113 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 13 last change occurred 7w1d ago
          from TenGigabitEthernet1/0/39
  Number of topology changes 18 last change occurred 7w1d ago
          from GigabitEthernet1/0/35
  Number of topology changes 191 last change occurred 02:55:33 ago
          from GigabitEthernet1/0/5
  Number of topology changes 107 last change occurred 3d01h ago
          from Port-channel3
  Number of topology changes 13 last change occurred 7w1d ago
          from TenGigabitEthernet1/0/39

[Mark Malone]

thats clean looking , 1 recent change on g1/0/5 but nothing that should effect the Adtran link , the last all changed days ago so no continuous stp changes occurring locally

[msomerville99]

I started mirroring the port today to see what is passing over that connection but so far I see nothing out of the ordinary.  I will continue to run the capture to see what I see when the connection drops and hopefully I see something and I will report back here with what I find. 

[Mark Malone]

that will give you the most accurate, the wireshark find the working pattern between the 2 how they communicate capture it , then leave it run in background when it breaks stop it and compare against the working connection with the time it failed

[paul driver]

Hello

So you saying the switch not the switchport is unable ping the the voice gateway.

Which means then the hosts at that time wont be able to renew dhcp allocation, or is it just the hosts that lose connectivity and if so do they have dhcp allocation at the time and can you ping them from the switch?

Is the voice gateway directly connected to this switch?
Does dhcp server have enough leases?

res

Paul