The advantages of the 6-connector channel

Transcription

1 APRIL 2007 The advantages of the 6-connector channel The advantage of sticking to standardised rules such as ISO11801 (that define the performance of the components, the performance of the whole cable channel, the distance limitations, and the number of connections allowed) is that it gives complete confidence that your IT application is supported by the cabling system. If for example you have constructed a conformant Class D cable channel out of Category 5e components then the 10/100/1000 Mb/s Ethernet card or switch you connect to it is effectively guaranteed to work by the manufacturer of that item. If you fail to obey the cabling rules then you are on your own regarding the network performance. The structured cabling standards call for a four-connector cabling channel model in the horizontal cabling. This can be seen in ANSI/TIA/EIA-568-B, ISO and EN The four connectors would be seen at; The Telecommunications Outlet () The Consolidation Point (CP) The two connectors encountered if a cross-connect configuration is used.

2 Campus Backbone Cabling CD Campus Distributor BD BD Building Distributor Building Backbone Cabling FD FD FD Floor Distributor Horizontal Cabling CP Consolidation Point Telecommunications Outlet The three level cabling hierarchy of ISO However, It can sometimes be a great advantage to have up to six points of interconnection in a cabling environment, particularly a complex data centre or computer room. This could allow any one item in the room to be connected via cabling and patch panels to any other item in the room; obviating the need for active Ethernet switching. Cabling for the data centre is defined in TIA 942 Telecommunications Infrastructure Standards for Data Centres and EN Information Technology - Generic Cabling Systems Part 5: Data Centres. These standards are effectively offering the same components and cabling rules as ISO 11801, but having to deal with a shorter and more compact installation; that in turn does not end in wall or floor mounted Telecommunications Outlets but more likely at a patch panel serving a cluster of equipment racks. Neither of these Standards describes exactly how to cable up your equipment and server racks. They offer guidelines and limits but leave a number of options and interpretations open to the user.

3 The three layer hierarchy of TIA 942 If, using the terminology of TIA 942, we have the Equipment Distribution Area (EDA) which may be a rack or a cluster of racks, in turn connected, possibly, to a Zone Distribution Area (ZDA) and then onto a Horizontal Distribution Area (HDA) and then on finally to the Main Distribution Area (MDA) and from there to the outside world via the Telecommunications Room and/or Entrance Room. We can start to see the number of passive connections that may be required. Of course the user can elect to place active equipment, principally Ethernet switches, in any one or more of the layers. If we work on the best practice principle of no patch cord leaving an equipment rack then we can see that the first point of connection comes at the patch panel, which must inevitably appear at the top of every cabinet. This cabinet would become our EDA. If we group together say five cabinets then we have a ZDA. One cabinet in the ZDA would be ominated as our communications rack and each EDA would be represented here by another patch panel hard wired to its counterpart in the EDA rack.

4 The physical connections through an EDA, ZDA, HDA and finally the MDA The ZDA is hard-wired back to the next level (i.e. the HDA) via a cross-connect, if no active switching is made here. If we were bound by the four connector rule, this would have to be our final call as it is the fourth connection and would now have to go into an active switch. We could not connect up to the MDA or back down the hierarchy again and form a hard-wired link to any other HDA (the TIA-942 makes it permissible to link across the hierarchy to the same tier as in Fig.6 HDA to HDA) as we would then be going beyond the allowable four points of interconnection defined in ISO A closer view of the HDA/ZDA showing the number of points of interconnection

5 Wouldn t it give a great deal of flexibility however if we were allowed six points of interconnection? It would mean that any piece of equipment in any rack could be connected by cable and patch cord to any other piece of equipment anywhere else in the data centre. Although this is not strictly within the spirit of the Standards it is possible if the cabling and patch panels are made with low enough attenuation and cross talk that even six of them in line will still meet all the horizontal cabling channel parameters. This is exactly what Connectix has achieved with its Express range of products. The superior quality of these products, in particular the insertion loss and Near End Crosstalk (NEXT) allows a six-connector configuration to be achieved and still meet the Class E or 10GBASE-T channel parameters. This gives enormous flexibility to the data centre designer and operator because they can now patch a service all the way up one leg of the hierarchy and down another. They may not choose to of course, or decide to insert Ethernet switches at one or more points in the hierarchy, but with products like Connectix Express the data centre manager has never had such flexibility of operation at his/her fingertips. Six connector channels give the greatest flexibility in data centres by allowing connections all the way up the full TIA 942 hierarchy or across the layers from one Equipment Distribution Area to another. Connectix can supply such guaranteed products and the technical support required to validate complex designs such as these. A 6 connector link from EDA to EDA via the HDA

6 The Fluke test data sheet below shows the margin achieved with an exceptionally difficult short distance test with six-connectors within a total length of only 33 metres. The Channel consists of three 10m fixed links and four 1m patch leads. Considering that most Standards recommend a minimum distance between interconnection of 15 metres this demonstrates the inherent performance margin in the Connectix products. UK Head Office: Connectix Limited 33 Broomhills Industrial Estate Braintree, Essex CM7 2RW