Patent Publication Number: US-2021181452-A1

Title: Multifiber invisible optical drop cable and methods for routing optical fibers within a multi-dwelling unit

Description:
PRIORITY APPLICATION 
     This application claims the benefit of priority of U.S. Provisional Application No. 62/924,792, filed on Oct. 23, 2019, the content of which is relied upon and incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to optical fiber cable processing, and more particularly, to optical fiber cable processing for a multiple dwelling unit (“MDU”). 
     BACKGROUND OF THE DISCLOSURE 
     Optical fibers are commonly used for voice, video, and data transmissions in many different settings each of which can pose installation challenges. In the installation of optical fibers in a multiple dwelling unit (“MDU”) (e.g., apartment buildings, hotels, etc.), there is typically a need to route optical fibers between various pieces of equipment. For example, referring to  FIG. 1 , a conventional MDU  10  is provided having a basement B 1  and floors A, B, C with individual dwelling units A 1 -A 3 , B 1 -B 3 , and C 1 -C 3  included in floors A, B, and C, respectively. As shown, a main terminal  26  is located in basement B 1  and is connected to a distribution cable  28 , which houses optical fiber(s)  30 . Fiber distribution terminals (FDT)  36  are located on each floor A, B, C, and subscriber optical fibers  32  extend from main terminal  26  to one or more of the FDTs  36 . Thus, the subscriber optical fibers  32  can be grouped between main terminal  24  and the FDT  36   s , with one or more of the subscriber optical fibers  32  being separated from the other subscriber optical fibers at a given FDT  36 . 
     From FDTs  36 , multiple subscriber drop optical fibers  38  are routed to subscriber termination points  34  (e.g., an adapter in a wall outlet, an adapter in a floor panel, an adapter behind a ceiling tile, or the like) such that the subscriber can optically connect directly (or indirectly in some situations) to the subscriber optical fiber  32 ) into each dwelling unit A 1 -A 3 , B 1 -B 3 , and C 1 -C 3  of MDU  10 . 
     One challenge that exists in installing optical fibers in an MDU is the resulting aesthetics of the housings or receptacles used to route the fiber optic cables (e.g., the FDTs and subscriber termination points  34  in  FIG. 1 ). These units can be visible and/or may be inconveniently placed within the MDU. Another challenge is the availability/creation of pathways for optical fiber drop cables. That is, there may not be enough molding available throughout the MDU to create hidden pathways, or the molding available may not affix onto every surface which can lead to the visibility of optical fiber cables within the MDU. Additionally, optical fibers can be difficult to manage/maintain due to the risk of incurring damage and need for protection. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to a process by which an optical fiber drop cable is created and routed in a multiple dwelling unit (“MDU”). The optical fiber drop cable is formed with a feeding tool, and the optical fiber drop cable includes a tube having optical fibers enclosed within the tube. The feeding tool creates a slit within the tube through which optical fibers are fed and thereby inserted into the tube along the tube&#39;s length. Once the tube exits the feeding tool with the optical fibers enclosed (thereby forming the optical fiber drop cable), the optical fiber drop cable is then routed into an individual dwelling unit of the MDU by a transition assembly including a transition plug and a routing plug that leads an optical fiber from an exterior of the individual dwelling unit to a subscriber termination point in an interior of the individual dwelling unit. 
     In one embodiment, a method of preparing and routing a plurality of optical fibers within a multiple dwelling unit (“MDU”) is provided. The method comprises: preparing an optical fiber drop cable by: creating a slit along a length of a tube; and directing the plurality of optical fibers through the slit such that the plurality of optical fibers extend within the tube along the length; arranging a transition plug on the optical fiber drop cable at a first location by: extending the optical fiber drop cable through a routing channel that extends through the transition plug, wherein the transition plug also includes a transition channel that communicates with the routing channel; and extracting at least one optical fiber from within the tube using the slit and extending the at least one optical fiber through the transition channel of the transition plug; routing the at least one optical fiber from the transition plug into a first dwelling unit of the MDU by extending the at least one optical fiber through a wall of the MDU; and mounting the transition plug to an exterior side of the wall of the MDU. 
     In another embodiment, routing the at least one optical fiber from the transition plug into the first dwelling unit of the MDU comprises extending the at least one optical fiber through a routing plug secured to the wall; and mounting the transition plug to the exterior of the wall comprises coupling the transition plug to the routing plug to form a transition assembly that traverses the wall and provides a pathway for the at least one optical fiber from the exterior side of the wall to the interior side of the wall. In another embodiment, the routing plug includes an entry channel extending from the interior side of the wall, and wherein the entry channel communicates with the transition channel of the transition plug when the transition assembly is formed. In another embodiment, routing the at least one optical fiber from the transition plug into the first dwelling unit of the MDU is performed before coupling the transition plug to the routing plug. 
     In yet another embodiment, the transition plug arranged at the first location on the optical fiber drop cable is a first transition plug, the at least one optical fiber routed into the first dwelling unit is at least one first optical fiber, and the wall of the MDU is a first wall, the method first comprising: arranging a second transition plug on the optical fiber drop cable at a second location, wherein the second transition plug is similar to the first transition plug and arranged on the optical fiber drop cable in a similar manner such that, after arranging the second transition plug, at least one second optical fiber is extracted through the slit of the tube and extends through the transition channel of the second transition plug; and routing the at least one second optical fiber from the second transition plug into a second dwelling unit of the MDU by extending the at least one second optical fiber through the first wall of the MDU or a different wall of the MDU. 
     In another embodiment, preparing the optical fiber drop cable further comprises: inserting the plurality of optical fibers into a first portion of a feeding tool; inserting the tube into a second portion of a feeding tool; and causing relative movement between the tube and the feeding tool so that a blade of the feeding tool creates the slit along the length of the tube, wherein the feeding tool directs the plurality of optical fibers through the slit and into the tube during the relative movement. In another embodiment, the feeding tool further includes a wedge structure configured to engage with the tube and open the slit of the tube such that the plurality of optical fibers can be directed through the slit. In another embodiment, the feeding tool includes a front aperture and a rear aperture between which passage is defined, wherein the wedge structure is proximate the front aperture. In another embodiment, the wedge structure is integrally formed with a body of the feeding tool. 
     In one embodiment, a method of preparing and routing fibers within a multiple dwelling unit (“MDU”) that includes at least one dwelling unit is provided. The method comprising: preparing at least one optical fiber drop cable by: inserting at least one optical fiber into a feeding tool, wherein the feeding tool includes a blade and at least one passage, the blade protruding into the at least one passage; inserting a tube into the at least one passage such that the blade creates a slit in the tube; directing the at least one optical fiber into the slit of the tube to create the at least one optical fiber drop cable, wherein the at least one optical fiber extends along a length of the at least one optical fiber drop cable; inserting the at least one optical fiber drop cable into a transition plug by: inserting the at least one optical fiber drop cable into a routing channel of the transition plug; extracting at least one optical fiber from the at least one optical fiber drop cable and inserting the at least one optical fiber into a transition channel of the transition plug such that the at least one optical fiber protrudes from the transition plug; inserting the transition plug into a wall of the at least one dwelling unit such that the at least one optical fiber extends into the at least one dwelling unit; and coupling a routing plug to the transition channel of the transition plug such that the transition plug and the at least one optical fiber that has been inserted into the transition channel are securely mounted to the wall, wherein the routing plug includes anchor structures to engage the routing plug within the wall. 
     In one embodiment, the feeding tool includes: a body including a first surface and a second surface positioned opposite the first surface; a first aperture positioned on the first surface and configured to receive a first optical fiber; a second aperture positioned on the second surface and positioned opposite the first aperture, the second aperture configured to receive a second optical fiber; and an internal passage between the first aperture and the second aperture, the internal passage configured to route the first optical fiber and the second optical fiber within the body. In another embodiment, the at least one passage of the feeding tool includes: a first passage and a second passage each within the feeding tool and each defined by the body, the second passage spaced apart from the first passage; wherein both the first passage and the second passage intersect the internal passage; and the blade is positioned within the body such that the blade extends into both the first passage and the second passage. 
     In another embodiment, preparing the at least one optical fiber drop cable further includes: inserting at least one first optical fiber into the first aperture; inserting at least one second optical fiber into the second aperture; inserting a first tube into the first passage whereby the blade creates a first slit in the first tube as the first tube is inserted into the first passage; inserting a second tube into the second passage whereby the blade creates a second slit in the second tube as the second tube is inserted into the second passage; directing the at least one second optical fiber through the internal passage and into the first slit of the first tube such that the at least one second optical fiber is within the first tube when the first tube exits the feeding tool to form a first optical fiber drop cable; and directing the at least one first optical fiber through the internal passage and into the second slit of the second tube such that the at least one first optical fiber is within the second tube when the second tube exits the feeding tool to form a second optical fiber drop cable. 
     In another embodiment, the feeding tool further includes: a first wedge structure extending into the first passage; a second wedge structure extending into the second passage; and wherein the first wedge structure and the second wedge structure are configured to open the respective first and second slits of the first tube and the second tube such that the at least one first optical fiber and the at least one second optical fiber can be inserted into the second tube and the first tube, respectively. In another embodiment, the first passage and the second passage have different sizes to accommodate different sizes of the first tube and the second tube. In another embodiment, the routing plug includes an entry channel coaxial with the transition channel, the routing plug configured to guide the at least one optical fiber into the at least one dwelling unit, and wherein the routing plug and the transition plug are telescopically mated such that the transition assembly can engage with and accommodate different wall thicknesses. In another embodiment, the transition channel of the transition plug includes a plurality of protrusions to engage with the routing plug. In another embodiment, the routing plug covers the transition channel of the transition plug such that the transition channel is within the entry channel of the routing plug. In another embodiment, the routing channel is substantially perpendicular to the transition channel. In another embodiment, the routing plug contacts an interior of the wall of the at least one dwelling unit and the transition plug contacts the exterior of the wall. 
     In one embodiment, a system for preparing and routing a plurality of optical fibers within a multiple dwelling unit (“MDU”) is provided. The system comprising: a tube for receiving the plurality of optical fibers; a feeding tool having a body, a passage extending through the body, and a blade extending into the passage, wherein: the passage is configured to receive the tube; the blade is configured to create slit in the tube when the tube is received in the passage; and the body is configured to direct the plurality of optical fibers through the slit and into the tube to form an optical fiber drop cable when there is relative movement between the feeding tool and the tube; a transition plug configured to be arranged on the optical fiber drop cable at a first location, the transition plug including: a routing channel for allowing the optical fiber drop cable to extend through the transition plug; a transition channel that communicates with the routing channel so that the transition channel can receive at least one optical fiber extracted through the slit of the tube; and a routing plug configured to couple with the transition channel of the transition plug to provide an entry channel that is coaxial with the transition channel. 
     Additional features and advantages will be set out in the detailed description which follows, and in part will be readily apparent to those skilled in the technical field of optical connectivity. It is to be understood that the foregoing general description, the following detailed description, and the accompanying drawings are merely exemplary and intended to provide an overview or framework to understand the nature and character of the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s), and together with the description serve to explain principles and operation of the various embodiments. Features and attributes associated with any of the embodiments shown or described may be applied to other embodiments shown, described, or appreciated based on this disclosure. 
         FIG. 1  is a schematic view of a conventional multiple dwelling unit (“MDU”) optical fiber routing map that includes a main terminal and associated fiber optic hardware, illustrating optical signal routing from a distribution cable to a main terminal via a cable assembly optical fiber to the main terminal, then to a fiber distribution terminal (FDT) via a subscriber optical fiber, and finally to a subscriber termination point via a subscriber drop optical fiber; 
         FIG. 2  is a bottom, perspective view of a feeding tool in accordance with the present disclosure; 
         FIG. 3  is a rear, perspective view of the feeding tool of  FIG. 2 ; 
         FIG. 4  is an exploded, perspective view of the feeding tool of  FIG. 2  illustrating the interior components of the feeding tool; 
         FIG. 5  is a side perspective view of the feeding tool of  FIG. 2  with a side cover separated from the feeding tool; 
         FIG. 6  is a perspective view of a portion of a passage of the feeding tool of  FIG. 2 ; 
         FIG. 7  is a rear view of a portion of the feeding tool of  FIG. 2  with a tube inserted into the passage of the feeding tool; 
         FIGS. 8A-8E  are perspective views of the feeding tool of  FIG. 2  that illustrate a method of assembling an optical fiber drop cable using the feeding tool; 
         FIG. 9A  is a perspective view of an alternate embodiment of a feeding tool in accordance with the present disclosure; 
         FIG. 9B  is a cross sectional view of the feeding tool of  FIG. 9A  illustrating the internal components of the feeding tool; 
         FIG. 10  is a perspective view of a transition plug used to route optical fiber drop cables in accordance with the present disclosure; 
         FIG. 11  is a top view of the transition plug with an optical fiber drop cable inserted into a routing channel of the transition plug and with an optical fiber extracted from the optical fiber drop cable and routed through a transition channel of the transition plug; the optical fiber is also protruding from the transition plug; 
         FIG. 12  is an exploded view of a transition assembly including the transition plug and a routing plug in accordance with the present disclosure; 
         FIG. 13  is a perspective view of the transition assembly of  FIG. 12  inserted into a wall separating a dwelling unit from a hallway of the MDU; and 
         FIG. 14  is a side view of the multiple dwelling unit (“MDU”) optical fiber routing map of  FIG. 1  but with the application of the optical fiber drop cables and the transition assemblies of the present disclosure to illustrate the simplified optical fiber routing map within the MDU. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will be clarified by examples in the description below. In general, the present disclosure relates to a process by which an optical fiber drop cable is created and routed in a multiple dwelling unit (“MDU”). The optical fiber drop cable is formed with a feeding tool, and the optical fiber drop cable includes a tube and optical fibers enclosed within the tube. The feeding tool creates a slit within the tube through which the optical fibers are fed and thereby inserted into the tube along the tube&#39;s length. Once the tube exits the feeding tool with the optical fibers enclosed (thereby forming the optical fiber drop cable), the optical fiber drop cable is then routed into an individual dwelling unit of the MDU by a transition assembly that leads an optical fiber from an exterior of the individual dwelling unit to a subscriber termination point in an interior of the individual dwelling unit. 
     Examples of feeding tools will be described first below, followed by a more detailed discussion of the method referred to above. It will be appreciated that feeding tools having different configurations may be used to achieve similar results. Thus, the methods in this disclosure are not tied to particular configurations of feeding tools except as set out in the claims that follow the description below. 
     Feeding Tool Used for Creating Optical Fiber Drop Cable 
     Referring to  FIGS. 2-5 , various views of one embodiment of a feeding tool  100  are shown. Feeding tool  100  is configured to create an optical fiber drop cable  128  ( FIG. 11 ), as will be discussed in greater detail below, and includes a body  102 , side cover  104 , and top cover  106 , which removably couple to one another to form feeding tool  100  having a passage  108 . 
     As shown in  FIGS. 2-6 , body  102  substantially gives feeding tool  100  an L-shaped configuration. However, it is contemplated that in other embodiments, other suitable shapes for feeding tool  100  may be used. Body  102  is also contoured to form a portion of passage  108 , which longitudinally extends through feeding tool  100  from a front opening  112  to a rear opening  114 . 
     Feeding tool  100  also includes a feeding channel  160  extending from front opening  112  to aperture(s)  110  in a first portion of body  102  as shown in at least  FIG. 2 . Thus, front opening  112  serves as an opening for both passage  108  and feeding channel  160  (the former portion of front opening  112  will be referred to as “outer opening” and is labeled with reference number  148 ). Aperture(s)  110  in the first portion of body  102  enable optical fiber(s) to be fed from front opening  112  and through the first portion of body  102 . In another embodiment, optical fiber(s) are fed from aperture(s)  110  and then through feeding channel  160  to front opening  112  when creating optical fiber drop cables as discussed further herein. 
     As shown in  FIG. 6 , a blade  118  protrudes into passage  108 , and a wedge structure  120  that is integrally formed with body  102  is located in passage  108  as well. Wedge structure  120  spans the distance from an end of blade  118  to front opening  112  and is configured to maintain or enlarge a slit  119  ( FIG. 7 ) of tube  122  as tube  122  advances through passage  108 , as will be discussed further below. 
     As mentioned previously, wedge structure  120  extends within passage  108  to front opening  112 . As shown in at least  FIG. 2 , wedge structure  120  defines a portion of feeding channel  160  extending from front opening  112 . 
     As mentioned previously, feeding channel  160  is in fluid communication with apertures  110  and functions to receive optical fiber(s). In addition, feeding channel  160  cooperates with apertures  110  to provide an insertion pathway for optical fiber(s) into slit  119  of tube  122  as discussed herein. 
     Outer opening  148  is defined primarily by top cover  106  and wedge structure  120 . As will be described in greater detail below, tube  122  can be fed through rear opening  114  and pushed through passage  108  to ultimately exit feeding tool  100  via outer opening  148 . 
     As shown in  FIG. 4 , body  102  also includes a recessed section  116  adjacent to passage  108  in a second portion of body  102 . Recessed section  116  is configured to receive a blade  118  and a side cover  104 . Blade  118  is seated within recessed section  116  of body  102  and protrudes into passage  108  when coupled to side cover  104  and body  102  as shown in  FIGS. 5-7 . Blade  118  is positioned adjacent rear opening  114  and functions to create a slit  119  within tube  122  ( FIGS. 8B-8D ) as tube  122  is inserted into the second portion of feeding tool  100  via rear opening  114 . 
     As mentioned previously, side cover  104  is seated within recessed section  116  and couples to body  102  to further define the shape of passage  108 . That is, when side cover  104  is coupled to body  102 , a lower boundary of passage  108  is defined such that the shape of the lower boundary of passage  108  longitudinally extends throughout a length of feeding tool  100 . As also mentioned previously, when side cover  104  is seated within recessed section  116  and coupled to body  102 , side cover  104  cooperates with body  102  to hold blade  118  therebetween. 
     Top cover  106  is seated on body  102  and side cover  104  to further define an upper boundary of passage  108  and to provide a protective cover for passage  108 . The installation of top cover  106  onto feeding tool  100  also defines the upper and lower boundaries of front opening  112  and the upper and lower boundaries (cooperating with side cover  104 ) of rear opening  114 . 
     Front opening  112  is configured to receive one or more optical fibers (e.g., optical fiber(s)  126  in  FIGS. 8A-8E ) fed through feeding channel  160  and a tube  122  fed through passage  108 , as discussed further in the next section of this description. Optical fiber(s)  126  may include a buffer tube or a buffer coating applied onto the optical fiber. For the purposes of the present disclosure, references to “optical fiber” include any of the aforementioned optical fiber constructions (i.e., with or without the application of a buffer tube and/or a coating). 
     Method of Using Feeding Tool to Create Optical Fiber Drop Cable 
     Referring now to  FIGS. 7 and 8A-8E , a method of creating optical fiber drop cables  128  is shown. Referring first to  FIG. 8A , a cap  124  is installed onto one end of optical fibers  126  and provides a protective covering for optical fibers  126 . Element  126  can be considered to represent a single optical fiber or multiple optical fibers, and is therefore referred to in this disclosure as “optical fiber(s)  126 ”. The other end of optical fiber(s)  126  is inserted into feeding channel  160  via front opening  112  along direction D 1  as shown. As can be appreciated from  FIG. 8B , optical fiber(s)  126  is routed through feeding channel  160  to exit aperture  110  ( FIG. 2 ). In an alternate embodiment, optical fiber(s)  126  can be fed through feeding tool  100  in an opposite manner, i.e., first being routed through aperture  110  until one end of the optical fiber(s)  126  protrudes from feeding channel  160  via front opening  112  or other apertures along top cover  106  (not shown). In such alternate embodiments, the protruding ends of optical fiber(s)  126  can be coupled to each other by an adhesive (e.g., tape, etc.). 
     Then, with reference to  FIGS. 8B and 8C , tube  122  is inserted into rear opening  114  of feeding tool  110  along direction D 2 . As tube  122  is inserted into rear opening  114  and into passage  108 , blade  118  cuts tube  122  to create a slit  119  within tube  122  along a length of tube  122  as shown in  FIGS. 7 and 8C . As tube  122  continues through passage  108  moving beyond blade  118 , tube  122  engages with wedge structure  120  such that wedge structure  120  maintains or enlarges the opening of slit  119  as tube  122  moves through passage  108  and towards front opening  112 . 
     Referring now to  FIG. 8D , optical fiber(s)  126  extending from feeding channel  160  are inserted into enlarged slit  119  of tube  122  as tube  122  exits feeding tool  100  via front opening  112 . Tube  122  also begins to disengage with wedge structure  120  such that enlarged slit  119  closes and reduces in size to substantially reform the original shape of tube  122 . Tube  122  is then pulled in direction D 3  as shown in  FIG. 8E  such that tube  122  disengages with wedge structure  120 , substantially reverts to its original shape, and encompasses or encloses optical fiber(s)  126  along the length of tube  122  to form an optical drop cable  128 . 
     Alternate Embodiment of Feeding Tool Used for Creating Optical Fiber Drop Cable 
     Referring now to  FIGS. 9A and 9B , an alternate feeding tool  200  is shown. As shown, feeding tool  200  includes a body  230  forming dual passages  210 ,  212  such that two optical fiber drop cables  128  can be created with feeding tool  200 . Feeding tool  200  includes a pair of front apertures  224 A,  224 B, a pair of rear apertures  222 A,  222 B, and respective first and second passages  210 ,  212  extending between the front apertures  224 A,  224 B and rear apertures  222 A,  222 B, respectively. First and second passages  210 ,  212  will be referred to as “upper and lower passages  210 ,  212 ” for convenience, given how feeding tool  200  appears in  FIGS. 9A and 9B . As shown in  FIG. 9B , upper passage  210  and lower passage  212  are spaced apart from each other and can have different sizes to accommodate tubes  216 ,  218  of different sizes. For example, as shown in  FIG. 9B , upper passage  210  may be sized to accommodate a tube  216  having a first diameter (e.g., 4 microns), and lower passage  212  may be sized to accommodate a tube  218  having a second, larger diameter (e.g., 12 microns). However, it is within the scope of the present disclosure that other suitable sizes may be employed. In another embodiment, upper passage  210  and lower passage  212  are of the same size. 
     Feeding tool  200  also includes a top aperture  206  on a top surface  202  of feeding tool  200 , and a bottom aperture  208  on a bottom surface  204  of feeding tool  200 . Top aperture  206  and bottom aperture  208  are each configured to receive optical fiber(s)  126  which are then directed into one of tubes  216 ,  218  as discussed further herein. Top aperture  206  and bottom aperture  208  have axes A 1  and A 2 , respectively, which are perpendicular to both longitudinal axes L 1 , L 2  of upper passage  210  and lower passage  212 . However, it is contemplated that in alternate embodiments top aperture  206  and bottom aperture  208  may be angled to one or both of longitudinal axes L 1 , L 2 . 
     Similar to upper passage  210  and lower passage  212 , an internal passage  214  extends from top aperture  206  to bottom aperture  208 . In particular, internal passage  214  extends from top aperture  206  to bottom aperture  208  such that internal passage  214  intersects and is in fluid communication with both upper passage  210  and lower passage  212 . As discussed herein, internal passage  214  is configured to route optical fiber(s)  126  within the body of feeding tool  200  and into tubes  216 ,  218 . 
     Similar to feeding tool  100 , feeding tool  200  includes a blade  220  within body  230  and upper and lower wedge structures  226 ,  228  adjacent blade  220 . As shown in  FIG. 9B , blade  220  includes an upper blade segment  220 A and a lower blade segment  220 B. Upper blade segment  220 A and lower blade segment  220 B protrude into upper passage  210  and lower passage  212 , respectively, and both blade segments  220 A,  220 B function to create a respective slit into tubes  216 ,  218  as tubes  216 ,  218  are fed into rear apertures  222 A,  222 B and are moved through upper passage  210  and lower passage  212 . 
     Similar to wedge structure  120  of feeding tool  100 , wedge structures  226 ,  228  are integrally formed with body  230  and are configured to maintain or enlarge the slits of tubes  216 ,  218  as tubes  216 ,  218  advance through passages  210 ,  212  and engage with wedge structures  226 ,  228  as discussed previously. This enables optical fiber(s)  126  to be directed into tubes  216 ,  218 . 
     To create optical fiber drop cables using feeding tool  200 , the steps are similar to those discussed previously with respect to feeding tool  100 . Optical fibers  126  are first inserted into top aperture  206  and bottom aperture  208  and fed into internal passage  214 . Once optical fibers  126  are inserted, tubes  216 ,  218  are inserted into respective rear apertures  222 A,  222 B and passages  210 ,  212 . As tubes  216 ,  218  are moved through passages  210 ,  212 , blade segments  220 A,  220 B create respective slits within tubes  216 ,  218 . After blade  220 , tubes  216 ,  218  move along respective passages  210 ,  212  and engage with respective wedge structures  226 ,  228  such that similar to wedge structure  120 , wedge structures  226 ,  228  maintain or enlarge the opening of the slits of tubes  216 ,  218  as tubes  216 ,  218  move towards front apertures  224 A,  224 B. 
     When tubes  216 ,  218  pass internal passage  214 , optical fiber(s)  126  are inserted into tubes  216 ,  218  via internal passage  214 . More specifically, optical fiber(s)  126  that are inserted into top aperture  206  are inserted through internal passage  214  and into the enlarged slit of tube  218  in lower passage  212 . Likewise, optical fiber(s)  126  that are inserted into bottom aperture  208  are inserted through internal passage  214  and into the enlarged slit of tube  216  in upper passage  210 . 
     As tubes  216 ,  218  continue through respective upper passage  210  and lower passage  212  and exit front apertures  224 A,  224 B, tubes  216 ,  218  disengage with wedge structures  226 ,  228  and the corresponding enlarged slits of tubes  216 ,  218  close returning tubes  216 ,  218  to their substantially original shapes with optical fiber(s)  126  enclosed. Tubes  216 ,  218  are pulled through passages  210 ,  212  for their entire length (or for a desired length) such that upon exiting front apertures  224 A,  224 B, tubes  216 ,  218  encase optical fiber(s)  126  to form a pair of optical fiber drop cables  128  for use in an MDU. 
     Installation of Optical Fiber Drop Cables within a Multi-Dwelling Unit (“MDU”) 
     Once optical fiber drop cables  128  are formed, optical fiber drop cables  128  are routed through a multi-dwelling unit (“MDU”) (e.g., MDU  10 A; see  FIG. 14 ) and individual optical fibers  126  are routed into individual dwelling units (e.g., A 1 -A 3 , B 1 -B 3 , or C 1 -C 3 , etc.). In particular, a transition assembly  150  ( FIGS. 12 and 13 ) may be used to route optical fiber drop cables  128  and individual optical fibers  126  throughout the MDU  10 A. In the embodiment shown, transition assembly  150  comprises a transition plug  130  and a routing plug  140  that may be coupled together. 
       FIG. 10  illustrates transition plug  130  in isolation. Transition plug  130  functions to route optical fiber drop cables  128  (and individual optical fibers  126  enclosed therein) within MDU  10 A in the vicinity of individual dwelling units (e.g., A 1 -A 3 , B 1 -B 3 , or C 1 -C 3 , etc.) of the MDU  10 A. In particular, transition plug  130  routes optical fiber drop cables  128  on an exterior or “hallway” side ( FIG. 13 ) of a dwelling unit and routes individual optical fiber(s)  126  towards the interior of the dwelling unit via routing plug  140 . 
     As shown in  FIGS. 10 and 11 , transition plug  130  is generally T-shaped. However, it is contemplated that in alternate embodiments, other suitable shapes may be used. As shown, transition plug  130  includes a routing channel  132  and a transition channel  134 . Routing channel  132  routes optical fiber drop cables  128  throughout MDU  10 A exterior to the individual dwelling units (e.g., through hallways passing by individual dwelling units). The exterior of transition plug  130  around the routing channel  132  includes ribs  138 , which are configured to engage with an exterior side  156  of a wall  152  ( FIG. 13 ) that separates an individual dwelling unit from the hallway as discussed further below. 
     Transition channel  134  is in communication with routing channel  132 , and transition channel  134  is substantially perpendicular to routing channel  132 . However, it is contemplated that in alternate embodiments, other angles between the transition channel  134  and the routing channel  132  may be used. Transition channel  134  provides a route for individual optical fiber(s)  126  of optical fiber drop cable  128  to be directed into individual dwelling units and more particularly, to subscriber termination points  34  ( FIG. 14 , e.g., outlets) within individual dwelling units. The exterior of transition plug  130  around transition channel  134  includes protrusions  136  that engage with routing plug  140  ( FIG. 12 ) when coupling routing plug  140  to transition channel  134  of transition plug  130 . In one embodiment, transition plug  130  (via protrusions  136 ) telescopingly mates (e.g., snap fit) with an interior of routing plug  140 . The coupling of transition plug  130  and routing plug  140  enables transition assembly  150  to be engageable with and adaptable to different thicknesses of wall  152  ( FIG. 13 ). 
     As mentioned previously, routing plug  140  is coupled to transition plug  130  to form transition assembly  150 . Routing plug  140  includes an entry channel  142 , a plurality of anchor structures  144  along an outer surface of the entry channel  142 , and an end plug  146  coupled to one end of the entry channel  142 . 
     Entry channel  142  couples to transition channel  134  of transition plug  130  such that entry channel  142  is substantially coaxial with transition channel  134 . More particularly, as shown in  FIG. 13 , when coupled to transition channel  134 , entry channel  142  encloses transition channel  134  such that one end of entry channel  142  is adjacent to the junction where transition channel  134  and routing channel  132  intersect. In an alternate embodiment, entry channel  142  partially encloses transition channel  134  of transition plug  130 . Entry channel  142  also functions to provide protective covering for the extracted optical fiber(s)  126  from optical fiber drop cable  128  as optical fiber(s)  126  travel through transition assembly  150  and into one of the dwelling units of the MDU  10 A. 
     As mentioned previously, a plurality of anchor structures  144  are integrally formed with an outer surface of entry channel  142 . Anchor structures  144  function to engage with a wall  152  ( FIG. 13 ) to hold transition assembly  150  in place within wall  152 . 
     End plug  146  engages with an interior side  154  of wall  152  once routing plug  140  is coupled to transition plug  130 . End plug  146  cooperates with anchor structures  144  to provide additional stability for transition assembly  150  when inserted into wall  152 . 
     To assemble transition assembly  150 , routing plug  140  is coupled to transition plug  130 . In particular, when coupling routing plug  140  and transition plug  130 , transition channel  134  is positioned at least partially within entry channel  142 , and protrusions  136  of transition plug  130  frictionally engage with an interior surface of entry channel  142  to secure the coupling of transition plug  130  with routing plug  140 . In this way, transition channel  134  is within entry channel  142 , and entry channel  142  provides a pathway for optical fiber(s)  126  to a dwelling unit of the MDU  10 A. 
     To install transition assembly  150  within MDU  10 A, an optical fiber drop cable  128  is prepared as discussed previously herein (e.g., with feeding tool  100 ,  200 ). Optical fiber drop cable  128  is then routed through transition plug  130 . In particular, optical fiber drop cable  128  is routed through routing channel  132  of transition plug  130  as shown in  FIG. 11 . When optical fiber drop cable  128  is inserted into routing channel  132 , the slit  119  in tube  122  (formed during preparation of optical fiber drop cable  128 ) is generally aligned with transition channel  134  of transition plug  130 . In this way, optical fiber(s)  126  designated for an individual dwelling unit of MDU  10 A is/are extracted from the optical fiber drop cable  128  (through slit  119 ) and inserted into transition channel  134  such that optical fiber(s)  126  protrude from transition plug  130  as shown in  FIG. 11 . In this configuration, transition plug  130  is directed into an aperture  149  ( FIG. 13 ) of wall  152  that extends from an exterior side  156  of wall  152 , through a middle section  158  of wall  152 , and to an interior side  154  of wall  152 . When inserted into aperture  149 , transition channel  134  is positioned within a middle section  158  of wall  152 , and optical fiber(s)  126  protruding from transition plug  130  extend into an individual dwelling unit. Thus, either before or during the positioning of transition plug  130  on wall  152 , the optical fiber(s)  126  protruding from transition plug  130  are routed through aperture  149  as well. 
     Once transition plug  130  is arranged on wall  152  as previously described, routing plug  140  is inserted into aperture  149  from interior side  154  of wall  152 . Routing plug  140  is also inserted over optical fiber(s)  126  that have been routed through wall  152  such that, once inserted into aperture  149 , routing plug  140  encloses optical fiber(s)  126  and at least a portion of transition channel  134  within wall  152 . Protrusions  136  on transition channel  134  engage with an interior surface of entry channel  142  to couple routing plug  140  with transition plug  130 . Additionally, end plug  146  engages with interior side  154  of wall  152  and ribs  138  of routing channel  132  engage with exterior side  156  of wall  152  to secure transition assembly  150  to wall  152 . Anchor structures  144  on entry channel  142  of routing plug  140  engage the middle section  158  of wall  152  to further secure transition assembly  150  to wall  152 . In this configuration, optical fiber(s)  126  extend through entry channel  142  and end plug aperture  147  ( FIG. 12 ) into the individual dwelling unit in question, and optical fiber(s)  126  can be further routed within the individual dwelling unit to designated subscriber termination points  34  ( FIG. 14 , e.g., outlets). 
     The method of installation described above can be repeated for other dwelling units. For example, transition assemblies  150  can be installed for other individual dwelling units such that optical fiber drop cable  128  and the corresponding optical fibers  126  for each dwelling unit are routed to the corresponding dwelling units as described herein. More specifically, a second transition plug  130  with a second optical fiber  126  is installed into a wall  152  of a second dwelling unit and a second routing plug  140  is coupled to the second transition plug  130  to form a second transition assembly  150  and to route the second optical fiber  126  into the second dwelling unit. 
     Referring now to  FIG. 14 , an optical fiber routing map of MDU  10 A is shown with the application of assembling and routing (via transition assembly  150 ) optical fiber drop cables  128 . Similar to MDU  10  of  FIG. 1 , MDU  10 A is provided having a basement B 1  and floors A, B, C with individual dwelling units A 1 -A 3 , B 1 -B 3 , and C 1 -C 3  included in floors A, B, and C, respectively. As shown, a main terminal  24  is located in basement B 1  and is connected to a distribution cable  28 , which houses optical fiber(s)  30 . Subscriber optical fibers  32  (e.g., multi-fiber cables comprising a plurality of optical fibers, such as ribbon fiber to provide one non-limiting example) extend from main terminal  24  and are optically connected to a fiber distribution terminal (FDT)  36  located on each floor A, B, C. FDTs  36  are provided to simplify the routing and installation of the optical fibers between the main terminal  24  and the subscriber termination points  34  by allowing the subscriber optical fibers  32  to be grouped between main terminal  24  and FDT  36  and then separated at FDT  36 . 
     From FDTs  36 , the subscriber optical fiber  32  is separated into a subscriber drop optical fiber cables  38 A for each floor, in accordance with the method described herein. The subscriber drop optical fiber cable  38 A is then routed to subscriber termination points  34  (e.g., adapter in a wall outlet, an adapter in a floor panel, an adapter behind a ceiling tile, or the like such that the subscriber can optically connect directly (or indirectly in some situations) to the subscriber optical fiber  32  in each dwelling unit A 1 -A 3 , B 1 -B 3 , and C 1 -C 3  of MDU  10 A via a transition assembly  150  installed into each dwelling unit as discussed previously herein. As shown in  FIG. 14 , the application of optical fiber drop cable preparation and optical fiber routing (via transition assembly  150 ) in MDU  10 A yields an optical fiber routing map in which fewer optical fiber drop cables are needed for the individual dwelling units on each floor. For example, in certain MDUs depending on the number of rooms per floor, a single optical fiber drop cable can be used to route optical fibers to each individual dwelling unit of the MDU. Additional relevant details regarding the configuration of an optical fiber network and optical fiber routing in an MDU (e.g., MDU  10 A of the present disclosure) can be found in U.S. Pat. No. 9,720,197, the disclosure of which is hereby incorporated by reference in its entirety. 
     There are many other alternatives and variations that will be appreciated by persons skilled in optical connectivity without departing from the spirit or scope of this disclosure. For at least this reason, the invention should be construed to include everything within the scope of the appended claims and their equivalents.