ATT FNet and ROiP issues. Is FNet a sales tactic?

[70cutlass442]

I am deploying a multi-site VHF high band P25 system. The system consists of two sites (to be expanded) that will utilize both repeater voting as well as subscriber voting. Both sites TX on separate frequencies and utilize subscriber voting to "roam", and the repeaters will vote the best signal on a common input frequency.

One site is at a remote location. Since we have FNet for in car MDC and cell phones, we added a Cradlepoint on our ATT FNet account to provide the link to the remote repeater. The repeaters began to experience issues when trying to pass data between each other.

After working with the manufacture, it was quickly determined that the cellular connection was the issue.

The test was simple, we sent 1500 bytes of data over the link using a CMD command and ran into 99% errors. I tried the same test on the squad MDCs with the same result. I then tired the same test on a FNet enabled laptop without a VPN connection, and had the same issue.

Now, I have a TMobile IoT card sitting here. One that cost me $5/month, not $45/month like Fnet. I ping 1.1.1.1 with 1500 bytes over an Ebay Netgear accesspoint and bam, sub 100ms returns.

Not a SINGLE FNet devices could give me these results.... Am I missing something, or is FNet really just more of a logo and a sticker?

The Cradlepoint had FULL bars, the Tmobile had 3...

 

[mmckenna]

Am I missing something, or is FNet really just more of a logo and a sticker?

FirstNet runs on top of the AT&T network.
It is essentially a logo and a sticker, but you would/should have priority over the average slob on the AT&T side. Isn't necessarily 'better' service, just that you have some level of priority.
Same radios, same back haul. Yeah, Band 14 where it's available, but regular AT&T users on that also, just that FN should have priority.
But, I don't think FirstNet is fully built out yet. You may be in an area that will show "FirstNet" and you should get service, but they may not have really built things out yet.

I tether my laptop to my FirstNet phone frequently, and haven't had any issues. I connect frequency both with and without VPN, and have had no issues connecting to my systems at work.

There have been times when it would suck, even though I had "full bars". My brother in law went through the same thing at his cabin, went through all the carriers and I think he finally found T-Mobile had the best service where he was, even though AT&T and Verizon all had a usable signal. T-Mobile just worked better. He had a cellular/WiFi modem, I don't think it was a CradlePoint, however. I helped him set up a log periodic antenna at his cabin, pointed back to where all the cell carriers were, and it wasn't a signal strength issue.

I'd call your FirstNet rep and ask them WTH? Let them address it. They have technical resources. Might be something with the site you are connecting to. Might be some interference with the band you are using with the connection.
And if they won't/can't fix it, well, there ya go, stick with T-Mobile and get on their priority plan.

 

[R8000]

I hope this is for ham or business use and not public safety.

 

[jeepsandradios]

The only way to know what the network needs is to follow the network plan for the system. An ethernet tester should get used to determine latency jitter and bandwidth meet the requirements. I've never seen a LTE link used in public safety applications for back haul. Too much unknowns with cellular providers. I assume this is ham or business use ?

As reference ATT is who does FN and in my dirt its useless. I have no service at home and when I get service in a few areas bandwidth is in the mud. Until I get to the "cities" its not reliable at all.

 

[MTS2000des]

We have a commercial LTE link as a failover for Smart Connect/Critical Connect should the primary WAN fail (which is an AT&T fiber circuit implemented by Verizon via MSI contract. MSI will use whatever fiber/DOCSIS is available to your prime site but they pay VZ). We had several fiber outages (due to aerial fiber being whacked by tractor trailers) lasting hours to a couple of days.

The LTE backhaul is a Cradlepoint and IIRC it's a VZW LTE carrier. It carried the load of SC/CC without any degradation but we're only pushing 10 licenses (talkgroups) so it's not like we're taxing it. I would never used fixed commercial carrier wireless from any of the three cartels for life safety/mission critical communications.

First Net is an overlay and supposedly leverages AT&Turd's band 14 spectrum for RAN and your magic black sim gives you priority over the thousands of users on Fakebook or ChinaTok uploading their pointless videos. I worked an event with around 100,000 people, all millenials, getting high and listening to so called "music" last fall in north Georgia. I have T-Mobile as a primary SIM and AT&Turd on an E-SIM on my personal iPhone 13 and both T-Mobile and AT&Turd had COWs on site connected via dark fiber to their cores. T-Mo experienced tremendous congestion as did AT&Turd. My county provided cell is on First Net with a black SIM, and it did work amazingly well, so their prioritization may actually work.

I don't trust any of the three wireless liars. They all overpromise, under deliver, engage in seedy tactics with billing, and have no accountability to consumers or businesses who pay them billions for subpar service.

 

[R8000]

I would never used fixed commercial carrier wireless from any of the three cartels for life safety/mission critical communications.

That was my concern. The OP's post says he plans to use it for RF traffic to connect sites then mentions about using it for MDC's (cruiser laptops?) which leads me to think it's for public safety.
I really really hope that isn't the case.

 

[mastr]

FirstNet runs on top of the AT&T network...you would/should have priority over the average slob on the AT&T side.

(1) That is why this "average slob" is not impressed with FirstNet- my "average slob" money is just as good as that of some FN user who preempts my call to decide where to have lunch with his/her buddies.

(2) I would be very reluctant to use FN for any sort of critical site to site connectivity. Or T-Mobile for that matter. Being dependent on someone else's infrastructure and staff is often a problem.

 

[lynchy135]

The test was simple, we sent 1500 bytes of data over the link using a CMD command and ran into 99% errors. I tried the same test on the squad MDCs with the same result. I then tired the same test on a FNet enabled laptop without a VPN connection, and had the same issue.

Most cellular networks have MTU that is lower than 1500 bytes.

Recommended MTU / MRU settings on cellular networks | Digi International

www.digi.com

While you can send 1500 bytes, it will need to be fragmented. It could be that the fragmentation isn’t happening for some reason.
Can you ping, let’s say, 1300? Work your way from there.

This is just one possibility, obviously.
This is definitely an issue you should work with your Firstnet TAC team though.

 

[KevinC]

Not answering your question, but in at least MSI comparators (and I’d imagine others) the link differential between sites can’t be more than 100 ms. So mixing low latency sites with high latency could cause issues.

 

[jeepsandradios]

I guess the other question is how is the link engineered ? Is this a router tunnel that keeps dropping or is it just a P-P link from the IP connection on the repeater.

 

[mmckenna]

(1) That is why this "average slob" is not impressed with FirstNet- my "average slob" money is just as good as that of some FN user who preempts my call to decide where to have lunch with his/her buddies.

The purpose of FirstNet is to give public safety/critical infrastructure users priority on the network over average consumers when needed.
It has nothing to do with your money, it has to do with need. Under contract pricing, we are paying considerably less for FirstNet than we were under AT&T. Day to day, I see no difference in the service between my FirstNet phone and my wife's AT&T phone. When things go wrong, I get better throughput. Toss in WPS for the phone calls, and I can get through when she can't.

(2) I would be very reluctant to use FN for any sort of critical site to site connectivity. Or T-Mobile for that matter. Being dependent on someone else's infrastructure and staff is often a problem.

Agreed. However, unless you own the entire network, be it point to point radio, fiber, copper, dial tone, dry pair, tone remote, IP link, or whatever, it's still someone else's network. Sometimes there is no other option and you have to do what you have to do.

Since the OP hasn't replied, the idea that it is the only link he is relying on for actual public safety radio, is pure guesses.

 

[mastr]

@mmckenna - I suggest that we agree to disagree about AT&T's preemption of the "average slob" for "public safety/critical infrastructure users" via FirstNet- AT&T should have built out adequate infrastructure to carry FN without dropping this "average slob", who believes that his own needs are equally important to those of the average FN user. (and yes I am eligible, but think kicking off normal customers when my call may not be critical is unfair to them)

 

[Thunderknight]

Are you trying to pass traffic between 2 FirstNet devices? If so, talk to your AT&T rep to make sure you are using the best APN for that.

 

[mmckenna]

@mmckenna - I suggest that we agree to disagree about AT&T's preemption of the "average slob" for "public safety/critical infrastructure users" via FirstNet- AT&T should have built out adequate infrastructure to carry FN without dropping this "average slob", who believes that his own needs are equally important to those of the average FN user. (and yes I am eligible, but think kicking off normal customers when my call may not be critical is unfair to them)

Don't take it personal, nothing was directed at you personally. If you want to take it personal, that's your choice.

FirstNet service was designed by the FirstNet Authority, not AT&T. AT&T simply won the contract to provide it over their network. Other companies had the opportunity to bid on it.

No one is required to use AT&T and no one is required to use FirstNet. If you don't like the way AT&T is doing things, you can always switch to another carrier. But, be aware, they all have similar offerings where public safety/critical infrastructure users can get service that offers pre-emption.

As for the pre-emption, it may seem "unfair", but it's there for a good reason. FirstNet users, as well as the other providers, including WPS, all have different levels of pre-emption, so even users on these services can get pre-empted by higher priority users.

If it was such a bad idea, other companies wouldn't have copied the service.

And it was MUCH cheaper than the Feds trying to build out their own network. Even they were smart enough to realize that was a stupid idea.

 

[70cutlass442]

Most cellular networks have MTU that is lower than 1500 bytes.

Recommended MTU / MRU settings on cellular networks | Digi International

www.digi.com

While you can send 1500 bytes, it will need to be fragmented. It could be that the fragmentation isn’t happening for some reason.
Can you ping, let’s say, 1300? Work your way from there.

This is just one possibility, obviously.
This is definitely an issue you should work with your Firstnet TAC team though.

I've reached out to ATT so I await their response. This uses multicast so fragmentation would certainly cause issues.

Not answering your question, but in at least MSI comparators (and I’d imagine others) the link differential between sites can’t be more than 100 ms. So mixing low latency sites with high latency could cause issues.

The repeaters will buffer up to 480ms to account for network jitter.

I guess the other question is how is the link engineered ? Is this a router tunnel that keeps dropping or is it just a P-P link from the IP connection on the repeater.

This uses multicast, a VPN connects the remote site back to a private network that utilizes microwaves to connect the rest of the system. We use a 3rd party device that creates a tunnel that allows us to use the same subnet at all sites which is needed for multicast.

Are you trying to pass traffic between 2 FirstNet devices? If so, talk to your AT&T rep to make sure you are using the best APN for that.

FNet is only being used at one site, the rest is microwave and fiber. The remote site is unique in the sense the LOS is not attainable and connectivity in the area is limited. DSL and MAYBE cable is a possibility. That is actually my preference if they will connect to the site.

 

[mastr]

I should have known better. It is time for me to take another break from this board.

 

[flametamer]

FirstNet service was designed by the FirstNet Authority, not AT&T. AT&T simply won the contract to provide it over their network. Other companies had the opportunity to bid on it...

Wasn't FirstNet was originally designed to be a separate band for first responders that ANY cellular provider could offer service to? IIRC, it was imagined that you could go to your current provider and (if authorized) be moved to that band. AT&T saw an opportunity to provide this IF they could use the band as their own $$$ generator with out competition.

Dt

 

[70cutlass442]

Update:

It appears as if FNET is not allowing fragmentated data across their network. 1472 is the maximum packet size I can send. I would expect for the fragmented packet to just be sent (in two or more packets) and our device will reassemble the data stream on the other end. This issue appears to be unique to FNET as I have not been able to replicate the issue on Tmobile, Spectrum, or ATT fiber.

I await info from ATT to see if there is a way to resolve this.

 

[mmckenna]

Update:
...
I await info from ATT to see if there is a way to resolve this.

Interesting, thanks for sharing. My network skills are rusty, but that makes sense to the stuff behind the cobwebs in my brain.

 

[lynchy135]

Update:

It appears as if FNET is not allowing fragmentated data across their network. 1472 is the maximum packet size I can send. I would expect for the fragmented packet to just be sent (in two or more packets) and our device will reassemble the data stream on the other end. This issue appears to be unique to FNET as I have not been able to replicate the issue on Tmobile, Spectrum, or ATT fiber.

The Cradlepoint should be the one doing the fragmentation so if they really aren’t allowing it that means they are inspecting the packet headers. In the mean time you might be able to lower the MTU on the Ethernet interface of your repeater to say 1400 and see if you can get your repeaters to link.

Edit, if that still doesn’t work, and you want to figure it out, I personally would add another device below the cradlepoints on either side, create a tunnel between the two devices and have that do the fragmentation. Objective is to not let firstnet see the fragmentation and see if the packet gets passed through correctly. MTU opens a whole, frustrating, can of worms…