Communication Infrastructure Upgrade on Mauna Kea

Institute for Astronomy


The communications infrastructure on Mauna Kea is in need of upgrading to provide adequate service to existing and planned facilities on Mauna Kea, in particular Gemini and the Smithsonian Submillimeter Array (SMA). The upgrade includes replacing the four fiber optic cables currently serving CFHT, IRTF, Keck, and Subaru with a single fiber sheath, replacing the GTE Hawaiian Tel Cu cable and adding a GTE Hawaiian Tel fiber optic cable.

The improvements described in this report affect Gemini, CFHT, IRTF, Keck, Subaru, SMA, JCMT, and CSO and will focus on an effective use of the two 4-inch conduits running between HH-16 near CFHT and HH-23 near Keck.


Currently there are two 4-inch communications conduits extending along the northern route from the Summit Communications Room that serve CFHT, IRTF, and Keck. CSO and JCMT are currently served along the southern route. Four 4-inch conduits have been installed from HH-23 near Keck to HH-25 near Subaru. As part of the Gemini project, new communications infrastructure consisting of four 4-inch conduits will be laid between the Summit Communications Room and HH-16 near CFHT.

Currently, one of the conduits along the northern route contains a 200 pair GTE Hawaiian Tel Cu cable for telephone service and the other conduit holds up to four fiber optic cables. The fiber optic cables are currently used in the Summit Communications Network operated by the Institute for Astronomy. Both of these conduits are congested preventing any additional pull of cables without prior removal of existing cable(s).


The basic communication requirements for each facility on Mauna Kea include

  1. GTE Hawaiian Tel Cu cables for telephone (voice) connection (25+ pairs/facility)
  2. GTE Hawaiian Tel fiber optic cables for high bandwidth wide area connection (new)
  3. UH fiber optic cables for local area network around the summit and Hale Pohaku (minimum 6 pairs of fibers/facility)

GTE Hawaiian Tel currently does not have fiber optic access to any of the facilities.

Proposed Plan

The current plan calls for supplying the communication needs to Gemini, CFHT, IRTF, Keck, Subaru, SMA, JCMT, and CSO through the northern route.

The project is expected to be completed in two phases. The first phase comprises the infrastructure upgrade that the Gemini Project has planned between the Summit Communications Room (SCR) and CFHT. The second phase will commence once the conduits between Subaru and CSO have been installed as part of the SMA Infrastructure improvement.

Phase I

Phase I will include a replacement of the main fiber distribution center in the SCR. The new rack with fiber optic distribution panels will be chosen to accommodate future expansion of the network, including any transitional work required. The existing fiber optic distribution panels can and will be relocated to the new rack before Gemini pulls in the new fiber sheath.

Gemini will pull a single new fiber sheath containing at least 32 fibers through the new conduits from the Summit Communications Room to HH-16 at CFHT. These fibers will be field spliced to the existing MKOCN fibers leading to CFHT, IRTF, Keck, and Subaru with the understanding that fibers currently in use will not be cut until it has been confirmed that the new fibers perform satisfactorily.

Phase II

During Phase II, the four separate fiber optic cables (between CFHT and Keck) and the fiber optic cable installed during Phase I serving CFHT, IRTF, Keck, and Subaru will be replaced by a single sheath of fiber optic cable containing up to 12/16 bundles of 6 pair fiber optic cable (or 24/32 bundles of 3 pair fiber optic cable, depending on the vendor) for a total of 144/192 fibers. The diameters of the 144 and 192 fiber cable are approximately 0.85" and 1" respectively. Each of the 8 facilities (Gemini, CFHT, IRTF, Keck, Subaru, SMA, JCMT, and CSO) will be allocated up to 12 pairs of fiber optic cables, tripling their current capacity. The fiber optic cable will be field spliced at hand holes near each facility to fibers leading to the patch panels in each facility. The main fiber optic cable will terminate near CSO with any unused fibers left un-terminated.

GTE Hawaiian Tel will pull an additional bundle of fiber for its own use and replace its 200 pair Cu cable at the same time.

One 4-inch conduit can hold either three 1 1/4" subducts or one 200 pair Cu cable and two 1 1/4" subducts. The 72/96 pair fiber optic cable will be pulled through a subduct. There are three possibilities for using the two 4-inch conduits; which one is best requires further analysis. The possibilities are:

  1. IfA fiber (f) in one conduit, and GTE fiber (F) and Cu cable (Cu) in the other conduit. This option physically separates the UH and GTE cables. This option prevents an upgrade of the Cu cable without disrupting fiber optic based service offered by GTE.

  2. The IfA and GTE fiber share a conduit. The GTE Cu cable resides in the other. The configuration allows for an upgrade of the Cu service without interruption of fiber based services (currently favored).

  3. The IfA and GTE cables all share one conduit. leaving the second conduit free for future expansion.

Proposed Implementation Procedure

Phase I
  1. IfA replaces Summit Communications Room distribution panel.
  2. Gemini pulls one 32-fiber sheath from the SCR to HH-16 through new conduit and splices pigtails to the fibers at the SCR distribution panel.
  3. Gemini/HawTel pulls new Cu cable through the new conduit and splices it to the existing Cu leading to CFHT, IRTF, Keck, and Subaru.
  4. For each of the following facilities (CFHT, IRTF, and Keck), Gemini will:
    1. Identify the existing fiber bundle leading to the facility.
    2. Identify the currently unused fibers in the old sheath and field splice those fibers to the new fibers.
    3. Test the newly spliced fibers.
    4. Splice the remaining fibers to the facility.
  5. IfA reestablishes the MKOCN.
  6. Gemini removes the four old fiber cables from the old conduit between the SCR and HH-16.
Phase II (assuming Option 2 under 4.2)
  1. GTE Hawaiian Tel (HawTel) pulls permanent Cu cable (Cu-1) between CSO and Keck through the new conduits and temporarily splices the cable to the Cu cable (Cu-0) connecting the SCR and CSO.
  2. HawTel provides temporary service to Subaru and Keck through Cu-1.
  3. HawTel pulls out old Cu between Keck and IRTF.
  4. HawTel pulls in 3 subducts in conduit (A) between Keck and IRTF.
  5. HawTel pulls in temporary 25 pair or less Cu cable (Cu-2) through one of the subducts and splices it to Cu-1 to provide temporary service to IRTF.
  6. HawTel removes old Cu trunk between CFHT and IRTF and pulls three subducts into the empty conduit (A).
  7. HawTel pulls in new 72/96-pair MKOCN fiber and its own fiber from Summit Communications Room to CSO through the subducts in conduit (A).
  8. Fibers leading to the patch panels of CFHT, IRTF, and Keck/Subaru will be spliced to the new (Phase II) MKOCN fiber sheath.
  9. The FDDI ring will be reconnected using the new fibers.
  10. The old MKOCN fiber optic cables will be removed from the Conduit B.
    1. The 32-fiber sheath installed during Phase I can be removed at this point.
  11. HawTel will pull in the new Cu cable (Cu-3) from CFHT to Keck though Conduit B.
  12. Temporary Cu service to IRTF, Keck, and Subaru will switch from the temporary service, i.e. via Cu-1 and Cu-2, to Cu-3.
  13. HawTel removes temporary Cu (Cu-2) cable between Keck and IRTF.
  14. HawTel disconnect Cu-1 from Cu-0, and splices any remaining Cu-1 pairs to Cu-3 pairs at Keck.

    Map of Area