Hey all. Question about standard 4 post racks. We bought some that are adjustable. Unfortunately, the posts are very flimsy, as these are some fancy cabinets with spacing on the sides for vertical patch panels, etc. We found that 2 post mounting of most Cisco devices (namely Cat 9500 1RU switches) are sagging quite bad. We’re used to the new server type rails that extend to support most reasonable distances front rails to back for 4 post mounting. However, for a Cisco ASA1001, there aren’t rails, but rather front and back ‘ears’ you use to hit both front and back posts. These would appear to not have any adjustability, the front to back post distance would seem to need to match the ears, I assume they don’t adjust placement on the router much. Is there a ‘standard’ distance between front and back rails that devices usually adhere to? Googling didn’t find an answer readily. These are 19” wide cabinets by the way.
Thanks,
Chuck
I have not seen a standard on cabinets. I have gear in a wide variety of racks. Some of are real shallow. Some are deep. I use these to generically solve the sagging issue.
https://www.amazon.com/dp/B00XXDJASY?ref=nb_sb_ss_w_as-reorder-t1_k1_1_11&=&crid=EFCM0EZP8BMA&=&sprefix=navpoint+ra
NavePoint Universal 1U Rack Mount 4-Post Shelf Rail for Dell Compaq IBM HP APC - 33.5 Inches deep
amazon.com
Justin Wilson
j2sw@mtin.net
Hey all. Question about standard 4 post racks. We bought some that are adjustable. Unfortunately, the posts are very flimsy, as these are some fancy cabinets with spacing on the sides for vertical patch panels, etc. We found that 2 post mounting of most Cisco devices (namely Cat 9500 1RU switches) are sagging quite bad. We’re used to the new server type rails that extend to support most reasonable distances front rails to back for 4 post mounting. However, for a Cisco ASA1001, there aren’t rails, but rather front and back ‘ears’ you use to hit both front and back posts. These would appear to not have any adjustability, the front to back post distance would seem to need to match the ears, I assume they don’t adjust placement on the router much. Is there a ‘standard’ distance between front and back rails that devices usually adhere to? Googling didn’t find an answer readily. These are 19” wide cabinets by the way.
Thanks,
Chuck
for a Cisco ASA1001, there aren’t rails, but rather front and back ‘ears’ you use to hit both front and back posts.
Front and back ears? I’m not sure what an ASA 1001 is (ASR?) but my experience with these boxes is that they have a single pair of ears which can be mounted front OR back.
The heavier / deeper 1RU devices do tend to sag alarmingly.
Is there a ‘standard’ distance between front and back rails that devices usually adhere to?
If you’re thinking of setting the front/back distance to accommodate a specific device, table 2 might be of some interest:
https://i.dell.com/sites/doccontent/business/solutions/engineering-docs/en/Documents/rail-rack-matrix.pdf
There isn’t a standard for rack depth, AFAIK, but one typically sees anywhere from 27in/69cm – 50in/127cm, in my experience. 42in/106.7cm & 48in/122cm are quite common depth dimensions.
Others here may have more specific information.
You are talking about the depth of the entire *cabinet*, right?
I.e, how much floor space it occupies. Because the OP asked about
the distance between the front and rear mounting *posts*, not the
full cabinet depth. (127 cm between the posts would require the
cabinet to be 150-160 cm deep at least, and I have never seen racks
that deep. Last time I checked, the deepest racks from e.g. Rittal
were 120 cm.)
/Bellman
Lucky you with a 19" data rack. All I have are 23" telco racks but I will say, the 23" extension ears from Cisco are serious and my router chassis' don't sag.
Mark
We have used these with great luck. Might be able to find some 1U rails instead of the standard 2U.
https://www.amazon.com/APC-SU032A-4-Post-Rackmount-Rails/dp/B00007L3MX
Hey all, sorry I did mean to say ASR1001 (an X model to be exact). The 4 post mounting they show in a hardware mounting doc uses front and back ears, which I’ve never done:
https://www.cisco.com/c/en/us/td/docs/routers/asr1000/install/guide/asr1routers/asr-1000-series-hig/asr-hig-1001.html#task_1205646
see figure 16 slightly down from there.
I do see some generic rails from TrippLite that probably would work, as well as shelves. I was hoping a standard depth that most vendors honored for 4 post existed, but it doesn’t seem likely. We’ll have a variety of PaloAlto, Cisco, Checkpoint, and others co-habiting.
Chuck
A bunch of devices (eg Juniper MX240) come with a “small mounting shelf” — see Figure1, Figure 2 at https://www.juniper.net/documentation/us/en/hardware/mx240/topics/topic-map/mx240-installing-the-router.html#id-installing-the-mx240-router-mounting-hardware-for-a-rack-or-cabinet
Their theory is that these get mounted on the “back” of the front rail, and it supports the weight of the chassis. I generally just put these on the font of the rear rail, and rest the back of the router on that. Seems to work well - the chassis is narrow enough to slide if the cabinet is very shallow, and the shelf is usually wide enough to deal with deeper cabinets…
The other option is “Universal Rails” (AKA “those funny sort of L bracket half shelf thingies”) — e.g: https://www.cablesandkits.com/racks-cabinets/rack-mount-shelves-and-rails/rackmount-rails/ck-rckmntrls/pro-18146
W
"small mounting shelf"
we use mounting shelves for all sorts of recalcitrant devices
randy
Yah, and for recalcitrant screws [0] , one of these: https://amzn.to/41Z0YQq . It’s super annoying, and somewhat terrifying to be banging on a rack containing a bunch of spinning rust, but all too often it’s necessary…
W
[0]: You know, the ones that someone decided to put in with an electric drill with the clutch set to “drill”, or the ones where someone put a 10/32 screw into an M6 hole, or…
It's super annoying, and somewhat terrifying to be banging on a rack
containing a bunch of spinning rust, but all too often it's necessary
we just moved a rack's content from the westin to komo plaza [0] and
only had one questionable drive. terrifying is the right word.
randy
[0] - we may be the first rat off the sad westin ship
Fascinating. I’ve never had an ASR-1001 come with two sets of ears, and I also note that the text of the instruction manual doesn’t reference the rear set at all. I’ve never seen rear ears on any Cisco gear of my own, nor on anything the local ILEC has installed either. I think the diagram is in error here.
However, the “optional” step 1 is a pretty solid hint (i.e. pretty much a clue-by-four upside the head, here!) that you really should use a shelf. As in you REALLY SHOULD USE A SHELF of some kind.
It doesn’t even have to be a full shelf – any rail kit that relies on an “L”-shaped profile instead of interlocking sliding bits should support an ASR-1001 just fine, e.g. Tripp-Lite’s 4POSTRAILKIT1U. RackSolutions’ Universal Fixed Server Rack Rails shows an example of a slightly different design that some prefer – it all works about the same way.
The other thing I’ve done is used a shallow cantilever shelf to support the rear end of equipment that only comes with ears, if it’s deep enough – something like StarTech’s CABSHELFV1U; the trick is finding a shelf that simultaneously doesn’t have the structural fold at the rear in the way AND doesn’t interfere with the device immediately below. You’d think there’re only 2 geometries of product to worry about, but there are actually more b/c there’s no standard – so test-fit first, or examine photos really carefully. This is usually more of a hack than a permanent, supportable solution, but sometimes it can work very well and very cheaply.
Or, just make sure you’re installing the ASR immediately above something that does have proper 4-post mounting rails. This is probably the single most common way to safely & securely mount “eared” devices in a 4-post rack that I’ve seen – that Dell PowerEdge server in the rack suddenly starts doing double-duty as a shelf! (Or the UPS, or the KVM, or the ethernet switch, or…)
-Adam
Hah! Your mention of clue-by-fours while we are talking about drooping routers reminds me of one of my more useful tools. I have a bunch of bits of 2x4 which I’ve cut to around 1.75", 3.5", 7".
These are really really helpful when trying to mount a piece of equipment under something which is either not screwed in, or is drooping at the back.
You can use these as spacers when replacing a bit of gear which is supporting other bits of gear, or, with a small shim/flat screwdriver as a way to jack up a devices which is drooping at the back (and so slide in another device). There are much more elegant solutions (like a machinist jack), but a few off-cuts of 2x4 are cheap, light, and non-marring.
This thread feels somewhat like “old NANOG” - people discussing actual issues that they run into, and then sharing tips and tricks to help with those issues. I miss this…
W
Hey all. Question about standard 4 post racks. We bought some that are
adjustable. Unfortunately, the posts are very flimsy, as these are some
fancy cabinets with spacing on the sides for vertical patch panels, etc. We
found that 2 post mounting of most Cisco devices (namely Cat 9500 1RU
switches) are sagging quite bad.
A perpetual problem with Cisco all the way back to their 2501 routers.
Sometimes they seem to come out with a better design, only to
revert back to the worst design the next generation of gear.
Is there a 'standard' distance between front and back rails
that devices usually adhere to?
I've got about 5 different "standard" depths in my datacenter. The
most common I have is 29.5" because that is the depth of a whole bunch of
fixed (ie. not adjustable) shelves I have are.
I've seen 32" and 36" in use for newer setups, as the eqiupment keeps getting deeper,
and deeper. Most equipment today will adjust for different depths quite
readily, and stick out past the back rails (so those 1050mm or 1200mm deep cabinets really
don't give you lots of empty space when the gear inside requires all that depth, then
power cables take up the rest).
So, ultimately the depth doesn't matter much as the rails will adjust to what you have
within reason now-a-days.
Gone are the days where equipment (ie. Sun, DEC) only fit in that one
rack that Sun paired with that specific Sun line. And when you bought different
Sun gear, you needed to buy a different rack to hold that.