TECHNOLOGY APPLICATION GUIDE

Network Cabling Architectures for Data Centers

What is it?

Centralized

Centralized

LAN/SAN switches are consolidated in a centralized MDA and HDA row.


End of Row

EoR – End of Row
LAN/SAN switches are located at the end of the network row within an HDA cabinet or rack.

Top of Rack

ToR – Top of Rack
LAN/SAN switches are located within the EDA cabinet or rack. HDA is not used in this configuration.

Middle of Row

MoR – Middle of Row
LAN/SAN switches are located in the middle of the network row within an HDA cabinet or rack.

Multiple network cabling architectures are available to provide connectivity to the various spaces within the data center.

ER – ENTRANCE ROOM

The space where the carrier circuits and demarcation equipment are located. For security reasons it is typically in a separate room than data center computer room.

MDA – MAIN DISTRIBUTION AREA
The space where core layer equipment such as routers, LAN/SAN switches, PBXs and Muxes are located.

HDA – HORIZONTAL DISTRIBUTION AREA
The space where aggregation layer equipment such as LAN/SAN/KVM switches are located.

EDA – EQUIPMENT DISTRIBUTION AREA
The space where access layer equipment such as LAN/SAN/KVM switches and servers are located.

ZDA – ZONE DISTRIBUTION AREA
The space where a consolidation point or other intermediate connection point is located

Why is it important?

ANSI/TIA-942-A Basic Data Center Cabling Topology


The selection of the network cabling
architecture is driven by both the
technical and financial factors of
the data center design. In general,
ToR architectures are better suited
for data center environments requiring
low latency and high-performance
server connections where EoR and
MoR architectures look to optimize
cost and flexibility





Network Cabling Architecture Application Pros Cons
Centralized Traditional cabling architecture where network switching is centralized in a row of HDA cabinets and racks. Due to shorter reach requirements, OM3/OM4 multimode cabling is used for backbone connections between MDA and HDA and Category 6A cabling between HDA and EDA. Typically deployed in small to medium sized data centers (<20K ft2 /1.8 m2)
  • Simple to design, implement and maintain
  • Minimized network bottleneck
  • Good port utilization
  • Easy device management
  • Large number of cables
  • Cable overlaps
  • Difficulties in cable pathway design
  • Lack of scalability

EoR- End of Row

MoR- Middle of Row

Utilizes a traditional MDA-HDA-EDA cabling topology, but the HDA is physically located at the end or middle of EDA cabinet row. OM3/OM4 multimode cabling is used for backbone connections and Category 6A cabling between HDA and EDA. Typically deployed in small to medium sized data centers (<20K ft2 /1.8 m2)
  • Fewer number of cables than direct-connect architectures
  • Good scalability
  • Cost effective compared to top of rack (ToR)
  • Increased mananagement overhead
  • Network stability risks due to potential Layer 2 loops that cause broadcast storms
ToR- Top of Rack Cabling connect ToR switch to server within the EDA cabinet or rack. Cable types include direct-attached cabling (DAC), OM3, multimode optical fiber jumpers, and Category 6A rated patch cords. OM3/OM4 multimode or singlemode cabling is used for backbone connection between EDA and MDA. Cabling architecture is deployed widely in hyperscale and cloud data centers (>100K ft2 /9.3 m2) where performance is at a premium over cost.
  • Efficient use of floor space
  • Excellent scalability 
  • Easy cable management
  • More switched to manager
  • More server-to-server traffic in aggregation layer
  • High network equiptment costs (redundancy)
  • Creation of hotspots due to higher density power footprint
Contact Anixter

If you have questions about the updated article or which fittings to use, contact your local Anixter representative or call 1.800.ANIXTER.