# ePMP Forward and Backward compatibility rules
**URL:** https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630
**Category:** ePMP
**Created:** [March 7, 2019, 7:21am UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630 "2019-03-07T07:21:22Z")
**Posts on this page:** 10
**Page:** 2
### Author:  [@Dmitry\_Moiseev](https://community.cambiumnetworks.com/u/Dmitry_Moiseev)
#### Post date: [November 7, 2019, 5:37pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/21 "2019-11-07T17:37:09Z")
Hi,
They will connect and pass data, but it is always recommended to run the same firmware on both AP and SM for stability puposes.
Dmitry
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### Author:  [@ninedd](https://community.cambiumnetworks.com/u/ninedd)
#### Post date: [November 7, 2019, 10:45pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/22 "2019-11-07T22:45:46Z")
planetcaravan said:
\>What about bacward compatibility if AP
\>is 4.4.2 (ePMP2000) and CPE are on 3.5.6?
In my opinion, that’s asking for trouble. It may work fine in some situations, but that’s playing with fire as far as I’m concerned. 🙂 If the AP is 4.4.2 then I would have all SMs as 4.4.2 as well.
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### Author:  [@Alejandro\_Pastrana](https://community.cambiumnetworks.com/u/Alejandro_Pastrana)
#### Post date: [April 10, 2021, 8:55pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/23 "2021-04-10T20:55:20Z")
Hello i was trying a link with force 300 and force 200 29km,
I will install other force 300
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### Author:  [@Eric\_Ozrelic](https://community.cambiumnetworks.com/u/Eric_Ozrelic)
#### Post date: [April 10, 2021, 9:05pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/24 "2021-04-10T21:05:41Z")
Looks like you’re trying to use ePTP? I think someone mentioned that ePTP is not compatible between different ePMP generations.
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### Author:  [@Alejandro\_Pastrana](https://community.cambiumnetworks.com/u/Alejandro_Pastrana)
#### Post date: [April 10, 2021, 10:02pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/25 "2021-04-10T22:02:57Z")
Yes i used eptp but here in mexico told me that they are compatible !!
But not
Dont wasted the time trying that !!
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### Author:  [@ninedd](https://community.cambiumnetworks.com/u/ninedd)
#### Post date: [April 11, 2021, 4:12am UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/26 "2021-04-11T04:12:04Z")
Yes, unfortunately ePTP mode isn’t compatible between generations for some reason. You should be able to use TDD or TDD PTP mode though. That’s no a perfect solution, BUT it’s a good solution to allow change one side of the link at a time.
ALSO - for us - at 29KM, we’ve found that TDD Mode has actually worked better than ePTP mode on our Force300’s. Your mileage may vary, but we found that under load and at distance, the Force300’s ePTP mode didn’t hold up like the 1000/2000 series does. We’ve been very pleased with TDD mode however. But, I’d be eager to find out your results.
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### Author:  [@Alejandro\_Pastrana](https://community.cambiumnetworks.com/u/Alejandro_Pastrana)
#### Post date: [April 11, 2021, 9:01pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/27 "2021-04-11T21:01:21Z")
Well, I will install the other force300, thanks for ur advice about TDD, i will reply tomorrow the result of this link, 29km the client only needs 10-15mbps
Thanks bro
Regards
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### Author:  [@Alejandro\_Pastrana](https://community.cambiumnetworks.com/u/Alejandro_Pastrana)
#### Post date: [April 13, 2021, 8:37pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/28 "2021-04-13T20:37:44Z")
Well i have done this link 29.645km with 2 force 300 -72-73, 4up/16down, eptp mode
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### Author:  [@ninedd](https://community.cambiumnetworks.com/u/ninedd)
#### Post date: [April 13, 2021, 9:48pm UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/29 "2021-04-13T21:48:08Z")
> [@Alejandro\_Pastrana](#):
>
> Well i have done this link 29.645km with 2 force 300 -72-73, 4up/16down, eptp mode
It would be interesting to see what it does in TDD PTP mode 75%/25%. I mean, the signals are barely functional, but I’d be curious to see anyway.
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### Author:  [@ninedd](https://community.cambiumnetworks.com/u/ninedd)
#### Post date: [October 22, 2024, 6:40am UTC](https://community.cambiumnetworks.com/t/epmp-forward-and-backward-compatibility-rules/60630/30 "2024-10-22T06:40:00Z")
Hi all. Is there a new chart like this with inclusion of the AX products?
Thanks!
[ ](https://d1okf4ta8xniw3.cloudfront.net/original/1X/e8e9d958556f644213a9519cc08045f511d6642f.jpeg)
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