6855-14D units - some comments
6855-14D units - some comments
Just a starting post - we've been using the 6850's and now the 6855 units for about 4 years now. We have about 200 of the 6855's in service and had good success with them. Primary configuration is the 6855-14D, with 48VDC power supplies and limited PoE. There is a known configuration issue when wanting redundant power supplies with PoE - it requires a total of three external power supplies which can be cumbersome to mount in a 19-inch rack. The units are very full-featured and have proven reliable in industrial environments.
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crosstowndon
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- Joined: 22 Jan 2010 13:36
- Location: Southern California
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Hi Don,
I spoke with my sales engineer soon after I spoke with you. He indicated that ALU has many units typically in stock in Calabasas, CA. When ordering, we typically are told 4-6 weeks for standard delivery, but it's usually more like 2-3 weeks. If you're looking for only one unit, I'm sure they must have one sitting on the shelf somewhere. Contact your local sales guy.
Good luck,
Clint
I spoke with my sales engineer soon after I spoke with you. He indicated that ALU has many units typically in stock in Calabasas, CA. When ordering, we typically are told 4-6 weeks for standard delivery, but it's usually more like 2-3 weeks. If you're looking for only one unit, I'm sure they must have one sitting on the shelf somewhere. Contact your local sales guy.
Good luck,
Clint
Just a few more comments to my earlier thread. The 6855 has one deficiency when it comes to the multiple power-supplies.
We had to engineer a new power-supply mounting solution when adding on the external PoE power supply. Essentially the issue occurs when a unit is configured with redundant primary power supplies (mounted in the attached power-supply shelf) and then the PoE power supply is added. There's nowhere to mount the external unit.
As a work-around, we had to use a separate 1.5 RU shelf and add the 6855, both DC primary PS units, and the third PoE supply to it. It's not the most elegant solution, but seems to work. A side benefit is that if a PS unit fails, they can be easily removed and swapped out.
Clint
We had to engineer a new power-supply mounting solution when adding on the external PoE power supply. Essentially the issue occurs when a unit is configured with redundant primary power supplies (mounted in the attached power-supply shelf) and then the PoE power supply is added. There's nowhere to mount the external unit.
As a work-around, we had to use a separate 1.5 RU shelf and add the 6855, both DC primary PS units, and the third PoE supply to it. It's not the most elegant solution, but seems to work. A side benefit is that if a PS unit fails, they can be easily removed and swapped out.
Clint
We are using a lot of the 6855 14 port, but without PoE, so fortunately we have not had as much problems with mounting power supplies.
Although we have had a few pains over the, I think, poor design on the power supplies mounting.
If mounted properly, following the installation guide, you can not quickly replace failed power supplies while they are rack mounted.
This is because of the top brace which is screwed in perpendicular to the rack, so you can't unscrew easily it without removing it from the rack.
We ended up drilling out the hole on the switch to make the screw from the bracket slide, like a pin, into the switch.
This made removing the bracket and power supplies a little easier while rack mounted.
Although we have had a few pains over the, I think, poor design on the power supplies mounting.
If mounted properly, following the installation guide, you can not quickly replace failed power supplies while they are rack mounted.
This is because of the top brace which is screwed in perpendicular to the rack, so you can't unscrew easily it without removing it from the rack.
We ended up drilling out the hole on the switch to make the screw from the bracket slide, like a pin, into the switch.
This made removing the bracket and power supplies a little easier while rack mounted.
Good point on the mounting - we found the power-supply shelf for the 6855-14D to be a little light for the intended mounting configuration. Not only does it restrict removal of the power supplies when the units are mounted in a rack (because of the bracket on top locking them in place), but it seems to sag slightly when installed. Ultimately our field staff engineered the solution that I described above, using the 1.5RU shelf and mounting all three power supplies on to the shelf. It makes for easier maintenance, but is disappointing that this is even an issue at all - I would expect that a large manufacturer like ALU would have tested this out. Ultimately the switch is full-featured and we are very happy with their network performance so far. Maybe they'll fix these power supplies in a future version. As a side comment, I have yet to see any of the 48VDC power supplies fail - they seem very reliable. Hopefully ALU will start engineering a 24-port version with no fans... 
HW Engineering - Enterprise
Hello Clint -
The 6855-14 has been designed to support up to 4 power supplies in a single 1U configuration, for thoise customer wanting backup System and backup PoE power.
In a 1U configuration, OS6855-U10 or -14 can support 1 tray along-side the OS6855-XX and one behind the 6855-XX This precludes buying further shelves.
We did observe some tolerance issues that led to some sagging, and some months back, we initiated an product enhancement request. The newer version of the rear shelf contains a bend to make is significantly stronger than before. Also, some improved tolerances eliminate any sagging that was observed.
If you can send me your contact information or the name of your local ALU support engineer, we can get you the necessary info to address the sag and mounting.
The 6855-14 has been designed to support up to 4 power supplies in a single 1U configuration, for thoise customer wanting backup System and backup PoE power.
In a 1U configuration, OS6855-U10 or -14 can support 1 tray along-side the OS6855-XX and one behind the 6855-XX This precludes buying further shelves.
We did observe some tolerance issues that led to some sagging, and some months back, we initiated an product enhancement request. The newer version of the rear shelf contains a bend to make is significantly stronger than before. Also, some improved tolerances eliminate any sagging that was observed.
If you can send me your contact information or the name of your local ALU support engineer, we can get you the necessary info to address the sag and mounting.
