The ultimate CMM alternative?

Looks like the parts to make a hardened version of a CMM are available. Total cost would be about $2,000 for 8 ports depending on enclosure used.

Last Mile Gear CTM-1m.DT0 - $899.00

8 port harsh environment industrial ethernet switch - 728.95:

Industrial Power Supply - 115.00 (24VDC/3.75A) - Need two

The CTM and switch feature redundant DC inputs. The power supply is sized to power both the CTC and the switch.

I am going to make this a priority and hopefully get it installed before winter. I’ll let you know how it goes.

Maybe you can ask Motorola to give you a test CMM3. It should have 16 ports and advanced management features like STP, real vlans etc.

I’ll look into it. Hopefully it is a more robust design. I have had 3 of the CMMmicros fail.

The advantage to the design above is the i can add another 8 ports very easily.

I have 80 CMMs, and no problems like yours. Usually the GPS module fails, but I can’t blame the CMMs because in the beginning we didn’t ground the GPS antenna properly.

We continue to use them because we don’t have big problems, except that they have small mac address table and with big numbers of subscribers they begin to act as a hub.

What was the cause of the failures?

Board level failure.

These are on the top of a mountain and I think the units just cannot take the abuse.

I have 3 CMM2’s on mountain tops.

Do you have them indoors our outdoors?

Usually the switches that come in the CMM2’s are piles…

Do you have any lightning supresssion in place for PoE, sync, and GPS coax?

UPS I assume on your gear?

What is the site grounding like?

CMM is properly grounded. We see virtually no lightning. CMM is outside on the tower.

AC power is OK, it was built for a lot of high power analog transmitters that are no longer active so power is pretty stiff - the transformer is huge. There is a generator that kicks on if grid power goes out. No UPS, they tend to cause more problems than they solve due to wide temperature swings abusing the batteries. I am planning on installing a commercial power conditioner to suppress spikes as I suspect that the switch between grid and generator may be part of the problem.

The last CMM failure has no excuse. Nice weather, no power issues. The CMM was working fine, then it stopped switching. Physically power cycled it and it came up for a minute and stopped switching again. Could not access any of the Web Interfaces.

Pulled the CMM board from the other tower and installed it and everything came right back up. Sent the bad unit in and the diagnosis was the broadcom switch chip. I agree, the switch is a POS. I doubt there is more than 100.00 worth of parts in the CMM.

I think the CMMmicro is the weakest point in my network and it needs to be beefed up as I have no confidence. Industrial components designed for abuse and extreme weather is what I am after. Additionally I can have a spare PSU, Switch, and CTM on hand. Initial cost will be higher but long term cost will be lower.

Ahh…CMM Micro… Yeah I do not use those. I see no gains for what they offer. I have Catalyst 2950’s at each site, so I have full VLAN support plus RSTP and the other goodies that are built into IOS. Plus I do not trust them… Your experience has validated my distrust reasons.

I guess Lastmiles solution is best then for your situation. If you need a more robust switch minus VLAN, I’d get something from Blackbox. I have a whole mess of their ExtremeEdge switches located on towertops and rooftops around the valley here for one of the networks I manage. Those things have survived some pretty crappy storms and our nasty summers and winters we have. One of the radios on that network (Airaya) got wacked from static but the switch kept ticking along.

Each site we are at has AC cooling already so temperature swings are not an issue for our UPS’s. We run the 2U models from Tripp-Lite with expanded battery packs. There was a fire on one of the mountain tops and the power co cut power. My gear was the only thing running on the site (in our building at least) and the outage was something like 10 hours. Never even ran out of battery… :wink: This site had a pair of the 3U battery packs, plus the batteries built into the UPS.

amd phreak wrote:
Ahh...CMM Micro... Yeah I do not use those. I see no gains for what they offer. I have Catalyst 2950's at each site

How do you provide sync?
erkan wrote:
[quote="amd phreak":1s22qh0o]Ahh...CMM Micro... Yeah I do not use those. I see no gains for what they offer. I have Catalyst 2950's at each site

How do you provide sync?[/quote:1s22qh0o]

We use CMM2's. They are the old version of the micro, but they have an 'industrial-grade' network switch built into them. I take the switch out, and only use the sync and PoE on the unit. I install Cisco 2950's on each site and those take the place of the switch.