Please help with questions on OC-3, "fiber ring"

Unanswered Question
Jan 11th, 2008

In a certain large facility, I have been asked to provide strong and reliable WAN circuit.

I am considering the deployment of a "fiber ring" served via two conduits, one conduit in the North and one conduit in the South of the data center.

My question is this:

1) If I deploy such fiber ring, what type of equipment I will need to terminate the OC-3 circuit? Is that the Cisco ONS series?

2) Bandwidth wise, my facility users would be satisfied with a 4.5Mbps (3xT1). However, with the fiber ring I will have a monster OC-3 (155Mbps) available. I am just wondering whether that is not an overkiller.

My question is, if my goal when deploying this fiber ring is to provide resilient and reliable WAN circuit, is there any other feasible and more cost effective way to provide this redundant WAN link other than the 'fiber ring'?

I have this problem too.
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Collin Clark Fri, 01/11/2008 - 08:26


Are you providing the connection to the WAN? How are you back-hauling to your companies infrastructure? How do you plan on dropping the connections off to the customers (serial, ethernet,etc)? How many customers are in the DC?

dmarekatc Fri, 01/11/2008 - 09:27


Well, you have a bit of an open-ended question (or set of questions). You mention proposing to have dual entrances - This certainly helps with physical problems that could occur within your premise (but beyond the outside vaults, you may need to continue to ensure there is diversity - to the COs, etc).

When it comes to terminating an OC-3 - Yes ONS gear can be used (and please don't take this wrong - I speculate you may not be ready to take that on yourself, unless you're already familiar with fiber/SONET/CWDM or DWDM... and know you need that technology - It can be outsourced), but several other devices (routers or switches - either providing L2 or L3) can terminate it - It really depends on what you're really trying to accomplish.

And that perhaps is the crux of the matter - It's a little unclear exactly what you're looking to do. You mention they want a reliable WAN circuit. OK - What does that mean exactly? A circuit to where? - Another company owned facility (and you need reliable, high-speed communications between them), so you want "private" fiber? Or is this WAN circuit really a provider's circuit? - Is this facility the head-end and you have X number of remote sites connecting in using Frame Relay, MPLS, Point-to-Points, VPNs across an Internet connection?, etc.

You mention only needing a fraction of the bandwidth - Then why is there consideration for an OC3? - A DS3 (fractional perhaps), multilinked or IMA'ed T1s, or an Ethernet hand-off could accomplish your needs. Again, all dependant on what you're specifically looking to do - You probably will want to ask yourself / them these types of questions.

For instance, if this WAN circuit is your head-end collection point from a service provider - You could have them bring Fiber/SONET into your facility (they'd make use of the dual entrance), and from there they would drop off services (T1's for voice or data, DS3s, Ethernet, Optical) to meet your needs. Of course in the example, that only helps make the main facility more reliable, the remote locations may not benefit to the same degree since usually there is only a single circuit to/from it (or even if there is dial backup, it probably comes from the same CO - though a different technology at least).

Hopefully that helps answer a few things, but maybe & more importantly, gets/keeps your wheels turning on the design.

Good luck.

news2010a Fri, 01/11/2008 - 10:18

That's a 1,000 users facility which need reliable WAN circuit to the rest of my organization. My headquarter and other major offices are on MPLS. The respective new facility would work as a branch office connected to my main headquarter.

I agree that OC-3 is an overkiller. That's exactly why I am asking this question. The problem is that the respective provider representative claimed that OC-3 or OC-12 are the options (or viable options) if I deploy the fiber ring. That's my point for my question. I really think the representative did not understand this right. I will ask him again.


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