• Data Center Comms Cabling

    From Don Y@blockedofcourse@foo.invalid to sci.electronics.design on Fri Apr 17 00:59:30 2026
    From Newsgroup: sci.electronics.design

    How do the network cables transition into/outof individual equipment
    racks in data centers? Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just
    a suitably sized *hole*? With lengths of cable that span the distance
    to a patch panel inside the rack? Is the service loop stored in the
    rack or allowed to clutter outside (beneath) the rack?
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  • From John R Walliker@jrwalliker@gmail.com to sci.electronics.design on Fri Apr 17 09:27:53 2026
    From Newsgroup: sci.electronics.design

    On 17/04/2026 08:59, Don Y wrote:
    How do the network cables transition into/outof individual equipment
    racks in data centers?-a Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just
    a suitably sized *hole*?-a With lengths of cable that span the distance
    to a patch panel inside the rack?-a Is the service loop stored in the
    rack or allowed to clutter outside (beneath) the rack?

    In the two data centres that I have visited the cables are all single-
    mode optical fibres. There is often a coil of excess fibre in the
    bottom of the rack just above the hole in the floor where they
    enter.

    John
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  • From noel@deletethis@invalid.lan to sci.electronics.design on Fri Apr 17 20:41:41 2026
    From Newsgroup: sci.electronics.design

    On Fri, 17 Apr 2026 00:59:30 -0700, Don Y wrote:

    How do the network cables transition into/outof individual equipment
    racks in data centers? Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just a suitably sized *hole*? With lengths of cable that span the distance to

    Yes, a floor panel is not installed along the line of racks, this permits cable management and airflow - traditional method of raised floors.

    Non raised floors have also need used for decades, but more prevailent in recent years and use cable trays from above into racks, easy as racks
    also come with overhead cable management access.

    a patch panel inside the rack? Is the service loop stored in the rack
    or allowed to clutter outside (beneath) the rack?

    not usually any patch panels - unless the customer supplies one for their local network there, usually the fibre (or 2+ if multi homed - footnote:
    if leasing rack in an internet exchange, they usually REQUIRE you to run
    BGP and take a peering feed with them) is dropped inside the rack with
    plenty length, and you connect it direct into your border router, since
    space and power is limited inside leased racks, its not worth using patch panels, go from server to switch direct usually with cat6 (6a is
    pointless over the barely 2 metres from any server position to your
    switch) and usually fibre from switch to router, but often that bit can
    be ethernet, its up to you as its inside your part of network.

    Cheers
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  • From john larkin@jl@glen--canyon.com to sci.electronics.design on Fri Apr 17 04:04:00 2026
    From Newsgroup: sci.electronics.design

    On 17 Apr 2026 20:41:41 +1000, noel <deletethis@invalid.lan> wrote:

    On Fri, 17 Apr 2026 00:59:30 -0700, Don Y wrote:

    How do the network cables transition into/outof individual equipment
    racks in data centers? Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just a
    suitably sized *hole*? With lengths of cable that span the distance to

    Yes, a floor panel is not installed along the line of racks, this permits >cable management and airflow - traditional method of raised floors.

    Non raised floors have also need used for decades, but more prevailent in >recent years and use cable trays from above into racks, easy as racks
    also come with overhead cable management access.

    a patch panel inside the rack? Is the service loop stored in the rack
    or allowed to clutter outside (beneath) the rack?

    not usually any patch panels - unless the customer supplies one for their >local network there, usually the fibre (or 2+ if multi homed - footnote:
    if leasing rack in an internet exchange, they usually REQUIRE you to run
    BGP and take a peering feed with them) is dropped inside the rack with >plenty length, and you connect it direct into your border router, since >space and power is limited inside leased racks, its not worth using patch >panels, go from server to switch direct usually with cat6 (6a is
    pointless over the barely 2 metres from any server position to your
    switch) and usually fibre from switch to router, but often that bit can
    be ethernet, its up to you as its inside your part of network.

    Cheers

    Are people still using SFP modules for the fiber links? Or something
    denser?


    John Larkin
    Highland Tech Glen Canyon Design Center
    Lunatic Fringe Electronics
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  • From Don Y@blockedofcourse@foo.invalid to sci.electronics.design on Fri Apr 17 06:05:58 2026
    From Newsgroup: sci.electronics.design

    On 4/17/2026 1:27 AM, John R Walliker wrote:
    On 17/04/2026 08:59, Don Y wrote:
    How do the network cables transition into/outof individual equipment
    racks in data centers?-a Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just
    a suitably sized *hole*?-a With lengths of cable that span the distance
    to a patch panel inside the rack?-a Is the service loop stored in the
    rack or allowed to clutter outside (beneath) the rack?

    In the two data centres that I have visited the cables are all single-
    mode optical fibres.-a There is often a coil of excess fibre in the
    bottom of the rack just above the hole in the floor where they
    enter.

    OK, the cable acting to carry the traffic for EVERY host in the rack
    to/from a "main switch", elsewhere.

    A switch inside the rack to handle the fan-out to the hosts INSIDE
    the rack? (that switch effectively acting like a patch panel
    for the rack)

    I suspect the "hole" is just a lifted floor tile, if the optical
    cable is "stored" in the rack? This (hole and service loop) not
    being an eyesore because:
    - it's hidden inside the confines of the rack
    - it's a data center and not expected to be aesthetically pleasing
    (err on the side of serviceable)
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  • From Don Y@blockedofcourse@foo.invalid to sci.electronics.design on Fri Apr 17 06:11:47 2026
    From Newsgroup: sci.electronics.design

    On 4/17/2026 3:41 AM, noel wrote:
    On Fri, 17 Apr 2026 00:59:30 -0700, Don Y wrote:

    How do the network cables transition into/outof individual equipment
    racks in data centers? Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just a
    suitably sized *hole*? With lengths of cable that span the distance to

    Yes, a floor panel is not installed along the line of racks, this permits cable management and airflow - traditional method of raised floors.

    The cosmetics aren't an issue, then (see my reply to John).

    Non raised floors have also need used for decades, but more prevailent in recent years and use cable trays from above into racks, easy as racks
    also come with overhead cable management access.

    Similarly, "not an issue".

    a patch panel inside the rack? Is the service loop stored in the rack
    or allowed to clutter outside (beneath) the rack?

    not usually any patch panels - unless the customer supplies one for their local network there, usually the fibre (or 2+ if multi homed - footnote:
    if leasing rack in an internet exchange, they usually REQUIRE you to run
    BGP and take a peering feed with them) is dropped inside the rack with
    plenty length, and you connect it direct into your border router, since
    space and power is limited inside leased racks, its not worth using patch panels,

    The router/switch serves the function of a patch panel. My point was, someplace for individual network cables from each host in the rack to interconnect (you're not running 20 cables into/outof the rack for
    the 20 hosts within)

    go from server to switch direct usually with cat6 (6a is
    pointless over the barely 2 metres from any server position to your
    switch) and usually fibre from switch to router, but often that bit can
    be ethernet, its up to you as its inside your part of network.

    I was thinking in terms of the datacenter belonging to and serving ONE
    entity. Like a large business..

    I need to reframe my question, then...
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  • From John R Walliker@jrwalliker@gmail.com to sci.electronics.design on Fri Apr 17 19:17:23 2026
    From Newsgroup: sci.electronics.design

    On 17/04/2026 14:05, Don Y wrote:
    On 4/17/2026 1:27 AM, John R Walliker wrote:
    On 17/04/2026 08:59, Don Y wrote:
    How do the network cables transition into/outof individual equipment
    racks in data centers?-a Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just
    a suitably sized *hole*?-a With lengths of cable that span the distance
    to a patch panel inside the rack?-a Is the service loop stored in the
    rack or allowed to clutter outside (beneath) the rack?

    In the two data centres that I have visited the cables are all single-
    mode optical fibres.-a There is often a coil of excess fibre in the
    bottom of the rack just above the hole in the floor where they
    enter.

    OK, the cable acting to carry the traffic for EVERY host in the rack
    to/from a "main switch", elsewhere.

    A switch inside the rack to handle the fan-out to the hosts INSIDE
    the rack?-a (that switch effectively acting like a patch panel
    for the rack)

    I suspect the "hole" is just a lifted floor tile, if the optical
    cable is "stored" in the rack?-a This (hole and service loop) not
    being an eyesore because:
    - it's hidden inside the confines of the rack
    - it's a data center and not expected to be aesthetically pleasing
    -a (err on the side of serviceable)

    A lifted floor tile would be much too big a hole. Its a small hole
    cut into a floor tile. Maybe 10 or 15cm diameter. Optical fibres
    are thin and a couple of power cables don't take much space.

    John

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  • From Don Y@blockedofcourse@foo.invalid to sci.electronics.design on Fri Apr 17 17:33:30 2026
    From Newsgroup: sci.electronics.design

    On 4/17/2026 11:17 AM, John R Walliker wrote:
    On 17/04/2026 14:05, Don Y wrote:
    On 4/17/2026 1:27 AM, John R Walliker wrote:
    On 17/04/2026 08:59, Don Y wrote:
    How do the network cables transition into/outof individual equipment
    racks in data centers?-a Presumably, through the floor?

    Regardless, how is the transition managed, physically -- is it just
    a suitably sized *hole*?-a With lengths of cable that span the distance >>>> to a patch panel inside the rack?-a Is the service loop stored in the
    rack or allowed to clutter outside (beneath) the rack?

    In the two data centres that I have visited the cables are all single-
    mode optical fibres.-a There is often a coil of excess fibre in the
    bottom of the rack just above the hole in the floor where they
    enter.

    OK, the cable acting to carry the traffic for EVERY host in the rack
    to/from a "main switch", elsewhere.

    A switch inside the rack to handle the fan-out to the hosts INSIDE
    the rack?-a (that switch effectively acting like a patch panel
    for the rack)

    I suspect the "hole" is just a lifted floor tile, if the optical
    cable is "stored" in the rack?-a This (hole and service loop) not
    being an eyesore because:
    - it's hidden inside the confines of the rack
    - it's a data center and not expected to be aesthetically pleasing
    -a-a (err on the side of serviceable)

    A lifted floor tile would be much too big a hole.

    I thought lifting the tile and leaving it partially in place
    (to expose a "slot").

    Its a small hole
    cut into a floor tile.-a Maybe 10 or 15cm diameter.

    So, if the excess cable is piled in the rack, do they "squeeze"
    the coil to feed it through said hole? (Or, pull it through one
    foot at a time?)

    -a Optical fibres
    are thin and a couple of power cables don't take much space.

    In any case, everything is hidden soas not to be an eyesore.
    And, everything is fixed in place so no fear of someone "moving"
    a rack, casually.

    My problem is more on the order of having the switch just outside
    the rack and cabling it's ports to the servers within. In a
    "clean" and robust manner.
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