Forum Discussion

Aspirant

Jul 26, 2016

Solved

GS728TS Stack issues with interfaces and LAG's

Hi,

We have 2 x GS728TS switches (running firmware 5.3.0.26) connected together in a stack with dual stacking cables.

There are 4 servers connected to the stack via LAG's. Each LAG consists of 4 members and 2 VLAN's, 2 on each switch in the stack. Each server runs multiple VMs.

Until recently everything was running fine. However last week we suddenly picked in an issue where some (not all) VM's on one host could not communicate with VM's on other hosts and vise-versa.

After investigating, we discovered that the ARP table entries on the troublesome VM's did not contain the correct entries. Restarting the VM did not resolve this. so I restarted the stack and after a long time (15 min) the stack came up and most of the issues disappeared, but not entirely.

So I checked the address table on the switch stack and found that this contains 'wrong' entries as well. It shows that some learnt mac addresses are on specific interfaces in place of on a LAG, and also sometimes these interfaces are not even part of the specified LAG.

If I power down one of the switches and keep it powered down (either one) then everything starts working correctly again.

Anyone have any ideas?

Thanks

Shaun

SRE
Aug 18, 2016
Hi,

During an extensive maintenance window last night, I powered down and removed all power to both switches in the stack for around 5 minutes.

I then re-applied power to both switches and after allowing then to boot up, checked them and they now appear to be working correctly again.

I have just re-checked the switches (approx 8 hours later) and they are still working fine - no issues noticed or detected.

Regards
Shaun

7 Replies

DaneA
NETGEAR Employee Retired
Jul 31, 2016
Hi SRE,

Just want to follow-up on this. Were you able to do a packet capture using Wireshark?

Regards,

DaneA

NETGEAR Community Team
- SRE
  Aspirant
  Jul 31, 2016
  Hi DaneA,
  
  Sorry for not getting back to you.
  
  I have not been able to do this as yet as we are in month-end lock down and no changes are allowed until after the 8th August.
  - JohnRo
    NETGEAR Employee Retired
    Aug 12, 2016
    Hi SRE,
    
    We’d greatly appreciate hearing your feedback letting us know if the information we provided has helped resolve your issue or if you need further assistance.
    If your issue is now resolved we encourage you to mark the appropriate reply as the “Accepted Solution” so others can be confident in benefiting from the solution. The Netgear community looks forward to hearing from you and being a helpful resource in the future!
    
    Thanks,
DaneA
NETGEAR Employee Retired
Jul 28, 2016
Hi SRE,

Welcome to the community! :)

I suggest you to set up port mirroring on the stack of GS728TS switches. Select a port(s) as a source port(s) on the GS728TS stack where the server(s) that runs multiple VMs is directly connected. Then, select another port as a destination port on the GS728TS stack where a PC with Wireshark installed in it is directly connected. Run Wireshark and observe if same problem will occur. It would be best that Wireshark would capture the packets on the event the problem occurs from the source port(s).

Kindly read page 278 of the GS728TS software administration manual here on how to set up port mirroring. You may download Wireshark on this link. As reference, you may check this link I found online on how to use Wireshark.

For the captured packets to be analyzed, kindly open an online case with NETGEAR Support regarding your concern. Attach the captured packets from Wireshark on the online case you have opened for it to be analyzed by the NETGEAR Support team.

Regards,

DaneA

NETGEAR Community Team