Check the route your taking when you use the cell phone as a hotspot and when you use the LTE modem. The carrier may be using different paths.
You may want to engage the vendor of your modem as well to make sure everything in it is configured correctly. Depending on the device there are a lot of tricky things that can be done with them. I only have experience with Cradlepoints and have used AT&T and Verizon. I know VZW used to route their "business grade" modems differently than their cell phones and consumer hotspots. I've been told VZW fixed the issue of having to put different tower configurations into the Cradlepoints (I believe the last time I set one up they were able to provision it without me configuring anything). High pings and high latency (compared to dedicated connections) have always been normal from my experience but with a decent signal it should still be better than a traditional DSL connection for example. Brian ________________________________ From: NANOG <nanog-boun...@nanog.org> on behalf of Dovid Bender <do...@telecurve.com> Sent: Friday, December 28, 2018 4:29 AM To: Brandon Martin Cc: NANOG Subject: Re: Cellular backup connections It's strange. When we use T-Mo on an andriod device the ping times are 30-40 ms. When we try with the modem + raritn console box it jumps to min of 100+ ms (the modem is high up on top of the rack and we test with the phones we are on the floor) - Can 5 feet higher make it that much worse? On Fri, Dec 28, 2018 at 7:23 AM Brandon Martin <lists.na...@monmotha.net<mailto:lists.na...@monmotha.net>> wrote: On 12/28/18 7:06 AM, Dovid Bender wrote: > Hi All, > > I finally got around to setting up a cellular backup device in our new > POP. I am currently testing with T-Mobile where the cell signal strength > is at 80%. The connection is 4G. When SSH'ing in remotely the connection > seems rather slow. Ping times seem to be all over the place (for > instance now I am seeing: rtt min/avg/max/mdev = > 174.142/336.792/555.574/99.599 ms) . Is that just cellular or is that > more related to the provider and the location where I am? I could in > theory test with VZ and ATT as well. With Verizon they charge $500.00 > just to get a public IP and I want to avoid that if possible. > > Thanks and sorry in advance if this is off topic. LTE with a good connection on a lightly loaded cell should be significantly less than that in both absolute terms as well as jitter. I used LTE (Sprint) for a couple years as my primary connectivity when I moved out into an area with zero connectivity (fixing that now). I typically saw ~30-40ms to Chicago, which is the nearest major carrier PoP. Jitter was typically less than 10ms. VoIP was usable. Others in the area on other carriers have reported similar. Sprint gave me a public IP with no up front charges but did charge $5/mo for it. As you're probably aware, the "signal strength" ("bars") indicators that are presented to the consumer-facing interfaces are often very cooked. Depending on which RSSI you're looking at, a "very good" signal is probably in the realm of -70dBm to -110dBm (note that there are two RSSI metrics commonly used with LTE, and they tend to differ by ~20dB). -- Brandon Martin
