Determining if CIR is for you, part 2

Continuing the discussion from the last issue, if you are deciding between CIR-based and zero CIR services, here are the pros and cons of using those that are CIR-based. After reading this issue, you should be able to make an intelligent decision about which one is for you.

The definition of CIR service is any frame relay service where a PVC has a CIR above zero. One benefit is that only packets sent above the CIR are marked discard eligible (DE). During times of network congestion, DE packets are the first to be discarded. All of your packets sent within CIR are "protected" from the first round of discarding. Also, by designating a CIR, you can determine which PVCs should be allocated the most bandwidth during times of bandwidth contention. You can use PVC CIR as a prioritization mechanism. Finally, your network design more closely matches your actual traffic patterns.

The negative aspects of CIR service is that usually the higher the CIR, the more a PVC will cost. For high-bandwidth connections your network costs could skyrocket. In addition, you are not guaranteed CIR, so why pay for it? Although there are service level agreements that claim 99.95% data delivery, they do not guarantee 100% of your data will get through. Besides, there are guarantees for zero CIR services, too.

Based on the past two articles, you now have the means to decide which service is best for you. For some customers, zero CIR is will satisfy their needs better, and for others, CIR is the clear winner.