Networking problem



  • We have a potential customer with a flat network, 30 pcs, 30 voip phones, 150mb comcast cable modem. we aren't using our own router but the comcast modem / router unit. Cisco DPC3941B. Switches are Netgear jgs524 gigabit unmanaged, phones are on 2 switches, computers on another 2 switches, all separate. All switches are brand new, all Cat6 cable is brand new etc.

    The PCS are all remote desktop service to our customer's server at Rackspace.

    Problem is nothing works, phones cut off, remote desktop cuts off. Comcast says not their problem. New cable brought into building, new cable modem, multiple comcast visits with tests of our connection. no trouble found is the story.

    Customer says no issue with this exact same setup at another location.

    Maybe our issue is Comcast. full stop.

    I see this as opportunity to solve a problem using pfsense. Whereby we have a pfsense unit with 1 wan, 2 lan (voice and data), respectively. Also we could use traffic shaping to balance the connection.

    Pfsense with their professional support solved my problem with another customer so I am grateful and hopeful there is opportunity for a solution.

    Must we dump those switches for managed units?

    Is there a recommended website where we can test the quality of our internet connection, not just speed, but latency and jitter



  • The PCS are all remote desktop service to our customer's server at Rackspace.

    Your running a VDI/RDS solution over a cable modem?  :-\

    How are they connecting to the RDS server? VPN?

    Implementing pfSense and managed switches will defiantly give you more viability into your network than what you have now.

    s there a recommended website where we can test the quality of our internet connection, not just speed, but latency and jitter

    Not sure how well it will compare with Rackspace but give this azure latency test a try:
    http://www.azurespeed.com/



  • How long do those failures last?  If any period of time, then it should be a simple matter to write a shell script that pings the ISPs gateway and time stamp the failures.  I did that several years ago, when I had a problem with my ISP.  The problem turned out to be a bad cable near the street.

    Here's the bash shell script I used on Linux.  It should be easy enough to run on BSD.

    #! /bin/sh
    while [ 1 ]
    do
            ping 99.229.52.1 -c 1 || date >> ~/log;sleep 60
    done

    Change the IP address as appropriate.

    This script will ping the ISP every minute and log the failure times.

    Incidentally, last week I also provided this script to Asus, to help them find a problem with my new tablet.  The WiFi would intermittently fail and they figured just watching Youtube for a while was a good enough test.  They were going to return the tablet to me unrepaired, until I told them to try the script for a couple of days.  They then found there was a problem as I described and the new, replacement tablet in now on it's way to me.  Knowing how to write simple scripts is a great way to uncover problems.  I was even doing it 40 years ago, in machine language on mini-computers.



  • @jsaad:

    Must we dump those switches for managed units?

    Do you require Layer2 features? Nothing wrong with Netgear unmanaged switches if you don't need the features, and can make sure the end users aren't creating network loops causing broadcast storms.

    I've had plenty of headaches with Comcast and their modems lately. We use them as backups at some sites and if you call in and the tech shows a green light on their screen, NO Problem. They don't care that our NMS show weeks of issues and proof that a problem exist. Its a cable modem after all. FYI, they just EOL their SMC devices this week so if you have one of those they can replace it.

    You can run the ping test like JKnott suggested but if you have several customers I would look at a free network monitoring system. We just moved from Zenoss to Zabbix and overall I'm really starting to like it. Search around to see which one works for you.



  • I attached a screenshot from our system for one of our Comcast Cable Modems. They can be helpful in determining how often problem occurs.

    ![Capture 91.PNG](/public/imported_attachments/1/Capture 91.PNG)
    ![Capture 91.PNG_thumb](/public/imported_attachments/1/Capture 91.PNG_thumb)



  • pfSense will help since you can also check the quality of your gateway, just make sure you set the monitor ip to 8.8.8.8.

    Pfsense with their professional support solved my problem with another customer so I am grateful and hopeful there is opportunity for a solution.

    Since you already had a great experience with them, give Netgate a call and explain your situation and they can recommend the right hardware for your needs.  pfSense won't fix an issue with your ISP if your having one, but you will defiantly have more insight on what is going on too fix them. You could also be saturating your bandwidth (Cable Modem, low upload) which the traffic graphs would show you.



  • If your customer is not reliant on having a local static IP address then have them buy their own modem (bridge only Broadcom based) and they will see many problems vanish.

    ;)



  • Thanks for the great advice.  I'm thinking putting in a test PFsense unit and monitor the gateway, I like that idea alot At least it's proof. Comcast calls them micro-outages which kills the remote desktop and the phone.  I'm not yet certain if it's over a VPN.

    I actually bought my own surfboard modem years ago to go direct to my monowall. Worked better than the netgear gateway provided by comcast.

    Welcome to the cloud.



  • @jsaad:

    Comcast calls them micro-outages which kills the remote desktop and the phone.

    It’s fairly common to see 2-10 seconds outages in cable modems, I see notifications all the time from our system and I normally see this on the same sites repeatedly. Usually ends up being signal fluctuations from somewhere up the street but the ISP don’t deem them problematic enough to fix. Higher latency and jitter are also known issues with these types of service and while most applications work fine with this, VDI and RDS do not. If your customer considers these application critical than they really need to look into a fiber solution. I prefer PRI over SIP for phones but it depends on the business and their current phone system. You could look at a low speed fiber for mission critical applications and push everything else out the modem.