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Diagnosing a Transient Network Issue via VPN

Hello! We are new to the NPM family (been using for a couple months). Very much enjoying the product, and loving the new UI. Now I am trying to use it for our most puzzling problem yet.

We have a VPN tunnel to a remote site using a Cisco 1921 at the remote end. NPM shows no issues with CPU/Memory/Bandwidth -- its all very low utilization. However my users report that their connection drops every 30 or 45 minutes for 30 sec, or a minute. Its enough to lose a ping packet or end a VOIP call. What is my best approach for using NPM to try and narrow this down or at least be notified when it is happening? I was reading up on creating quicker polling intervals to see if that would work, but I didn't know if there are any advanced settings that would be helpful?

Thanks so much!

-Chris

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Accepted answers

rschroeder

There are a few caveats for 100% successful NetPath deployment, particularly if going through firewalls and discovering external providers' nodes. If it's not working as needed, it's possible you may find it helpful to route it outside the VPN tunnel between your NPM server, through your firewall, to the outside interface of the remote VPN box. This way you'll discover all the intermediate hops between the VPN end points, which are otherwise invisible to NetPath when passing inside the VPN pipe.

Also, NetPath requires a few additional firewall ports to be opened:

I recently had an issue where users of a VPN were experiencing high latency and 24% packet loss. NetPath discovered problems between two intermediate providers several hops away from the ISP's on both sides of the VPN. Now Qwest/Century-Link/ATT/Cogent/CCI are working on the issue for me, instead of me spending cycles with frustrated users who aren't able to reliably transfer files through a VPN. NetPath really provided the details needed to identify the exact nodes that are dropping packets, many hops away from the two VPN ends.

If manipulating your firewall to accommodate NetPath's basic needs isn't an option, make sure you're using a discovery port that's open through your firewall to the outside of the remote VPN termination.

If NetPath isn't able to help you, something like PingPlotter may be useful. It can display information in graphic or text formats, and might be the work around to find and prove problems with intermediate nodes, as I did with NetPath.

All comments

john.ta

I don't think Solarwinds would be able to do anything for you in this instance if it is reporting everything as working fine. My recommendation would be to setup an IP SLA tracker on remote router and see if it is really having connectivity issues.

rschroeder

Is NetPath a good option for you? Imagine having a VPN path that passes through multiple providers, and one of them has issues. Knowing you've got packet loss isn't enough data to show where the problem is, but NetPath seems like it would be the tool to show where the issue lies.

cbeavs

I did try setting up Netpath by using a probe at the remote network to go out to the Internet. I can't get Netpath to show my complete path. I get a better look using tracert - I know after my firewall there is a timeout at the ISP router but then from there I get all the other routers on the way to Google. But none of them show up in netpath.

rschroeder

Also, NetPath requires a few additional firewall ports to be opened:

cbeavs

Thanks rschroeder! That is good info. So I need to open up ICMP Code 11 on my firewall for return packets to my NETPATH probe?