I am currently looking to upgrade internet connections in our major offices. Given that our reliance on cloud services has grown, some users are complaining of sluggishly behavior. After testing, as far as I can tell, it is primarily web traffic that is saturating our connection split relatively evenly across all hosts. As such, I have looked at the price of bringing fiber into the building, as well as T1 and OC3 options. But, I have noticed that a 100/100 fiber connection costs only slightly more than T1, with OC3 being ridiculously more expensive. Why is this? Are OC3 and T1 technologies not old and out-dated? Put another way, why would anyone use T1 over fiber in a location where both are available?


2 Answers 2


Yes, TDM technologies are old, but they are ubiquitous. The telcos would love to move everyone to IP, and they are working toward that goal.

There are telco customers who are comfortable with the old way of doing things, but as the cost disparity increases, even those customers will likely decide to come into the new world. That requires a capital layout for both the telcos and the customers.

The real problem is that TDM circuits are available everywhere, and it takes time and money to get IP-based circuits installed everywhere. Many times, the IP-based circuits that, you as the consumer see as fiber, are actually delivered by the telco as OCx circuits to a conversion box. You, the customer, only see then end result of the IP-based circuit. This is a temporary situation while the telcos work toward their goal.

FYI Edit:

One big problem we have discovered with ethernet delivered from the carriers is that when the link is actually down, the port still shows up because it is from the carrier equipment to our equipment. This hasn't really been a problem with leased or owned fiber, only with what we use to connect to to a carrier.

In the case of Metro Ethernet, we can mitigate the problem by using devices on each end of the link that support BFD which will drop the link, from the the routing protocol's perspective, far sooner than the routing protocol will determine the neighbor is down. It is still an irritant.

In the case where the actual circuit is delivered via TDM to a conversion box, we have declined to use the ethernet option becasue, so far, every time the TDM circuit is down, the ethernet shows up. All the carriers have promised to fix this problem with newer, different equipmet, but there is no real resolution, so far. BFD is not really an option to mitigate this case since the other end of the link is the PE, and the carriers don't play BFD with us.


You're right. You would just get a MetroE connection ( usually runs EoMPLS at the carrier). Prices are cheap. It gives symmetric speeds just like T1 does. And when you need to add more bandwidth, you just let the carrier know. They can add bandwidth in most cases without having to change your link or hardware.

Here are some additional things to consider:

  • For Metro ethernet (fiber), you'd simply use a fiber patch to connect your equipment to carrier demarc. For OC3, you need specialized modules.
  • If your network and everything is running ethernet already, why choose to convert to sonet, and back again?
  • Ethernet is scalable by design and this can save you money in the long run. A 100 meg ethernet fiber connection on a 1G eth port, can be scaled up or down later by the carrier without requiring additional hardware.
  • 1
    As long as it's a gig port, yes. I've seen carriers run 100meg on a 100meg port. (gig ports do cost more)
    – Ricky
    Oct 1, 2015 at 23:51
  • True. But there are only so many port speeds they provide - like 10m, 100m, 1000m. But their tiers here in the US start at 2megs, 4megs, 5megs and so on. Chances are you'll get an optic that can take more than the bandwidth you have now. But your point is valid.
    – ajaysdesk
    Oct 1, 2015 at 23:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.