Keeping pppd connection alive?


I followed the tutorial on the documentation with the Huawei E303 modem— everything works great, I can stand up a new connection, hit the internet, and tunnel back with spacebridge. (I’m using the stock configs from your documentation for pppd)

The problem is that the connection seems to go idle after about 15 seconds of non-use. So, if I try to connect with spacebridge, it basically sits waiting until it times out OR I do something on the device to re-establish the connection, like ping on the cell interface.

I can avoid the issue by having ping run continuously in the background on the device, but that feels hacky (and expensive in terms of data use).

If I issue a ping after the connection has gone idle, I can see that the first ping response takes significantly longer, around 2s, before dropping back down to around ~250ms… so something is obviously happening where the connection to the cell network is being stood back up.

Any tips on pppd configuration or where/how to start debugging so I can keep the connection alive without having to resort to running ping continuously?

Hi Steve - Thanks for reaching out! Our chat scripts should be keeping a persistent connection for pppd so we’re taking a further look. Can you provide more info about the hardware you have the E303 plugged into and what OS/distro is running?


Hey Ryan,

Thanks for replying!

I have it plugged into a RPI2 and it’s running Ubuntu 17.04. I can try a different OS/Hardware combo if you think it’s a factor.

Thanks Steve. Do you have a Raspbian distro you can try as well? And are you using Ubuntu’s NetworkManager? May be some conflict there to isolate. The ping times you mentioned sound normal, doesn’t indicate that the network connection is necessarily down though.

I just tried again with the default Raspbian install and I’m seeing the exact same issue. One new thing I noticed— the color of the indicator on the E303 changes… When I first bring up the connection, it’s bright blue. As soon as it goes “idle”, it changes to a darker blue. If I ping from the device, it turns back bright blue and I’m able to connect via spacebridge.

The E303 docs seem to say that the light color indicates whether it’s connected to 3G vs 3G+, but I’m not sure.

Could it be an issue with the modem? Any ideas?

Hello, has anyone had any news on this. Having exactly this issue with a Nova. Looking for a “non hack” way to keep the connection alive.

I have a Nova 4G/LTE plugged into a Raspi 3. It works as a GPS logger and sends it’s locations to a dashboard (Thingsboard). It only publishes above 2 or 3 km/h, to avoid useless data consumption when standing still.

Should I plan reconnecting/resetting the modem on each move? I personnally would prefer keeping the connection up, and only using it when required (the hologram network connect takes 6-7 seconds…).

Thank you!

I am experiencing the same issue described in this thread when I use an E303 modem with Spacebridge. When the light is cyan I am able to reach a webservice on the device, but when it turns to dark blue I cannot reach it anymore. When the color change happens it looks like it transitions the mode from 5,7 (HSDPA+HSUPA) to 5,4 (WCDMA). This appears to be normal behavior when the modem is idle, but doesn’t work properly with Spacebridge.

My temporary fix was to force the modem on GSM only (2G) using the following AT command: AT^SYSCFG=13,2,3FFFFFFF,1,2, but that isn’t really
a good long-term fix especially with 2G being phased out. Is this an issue on the Hologram side and/or is there a better workaround?