Standard DC rack rail distance, front to back question

Thu Apr 27 19:06:14 UTC 2023

On Thu, Apr 27, 2023 at 2:38 PM, Adam Thompson <athompson at merlin.mb.ca>
wrote:

> 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.
>

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

>
> 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 <https://www.rack-solutions.ca/rack-rails.html>
> 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
>
>
>
> *Adam Thompson*
>
> Consultant, Infrastructure Services
>
>
>
> 100 - 135 Innovation Drive
>
> Winnipeg, MB R3T 6A8
>
> (204) 977-6824 or 1-800-430-6404 (MB only)
>
> https://www.merlin.mb.ca
>
> Chat with me on Teams
> <https://teams.microsoft.com/l/chat/0/[email protected]>
>
>
>
>
>
> *From:* NANOG <nanog-bounces+athompson=merlin.mb.ca at nanog.org> *On Behalf
> Of *Chuck Church
> *Sent:* Thursday, April 27, 2023 10:36 AM
> *To:* 'Mark Stevens' <manager at monmouth.com>; nanog at nanog.org
> *Subject:* RE: Standard DC rack rail distance, front to back question
>
>
>
> 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
>
>
>
> *From:* NANOG <nanog-bounces+chuckchurch=gmail.com at nanog.org> *On Behalf
> Of *Mark Stevens
> *Sent:* Thursday, April 27, 2023 11:17 AM
> *To:* nanog at nanog.org
> *Subject:* Re: Standard DC rack rail distance, front to back question
>
>
>
> 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
>
> On 4/27/2023 10:04 AM, Chris Marget wrote:
>
>
>
> On Thu, Apr 27, 2023 at 9:53 AM Chuck Church <chuckchurch at gmail.com>
> wrote:
>
> 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
>
>
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