Minimum Internet Speed and Burst Speed, CIR vis-a-vis EIR

Let's read it from these to speed up your comprehension;

CIR (Committed Information Rate)

http://www.linktionary.com/c/cir.html

When you order a virtual circuit for a service such as frame relay or ATM, you can specify a guaranteed data rate that you want the carrier to provide. The data rate is negotiated with the carrier as the CIR (committed information rate).

When the data rate exceeds the CIR, the network starts dropping packets, so CIR should be a balance between the minimum and maximum bandwidth requirements. You can also negotiate a burst rate that lets you exceed the CIR rate to accommodate spikes in traffic. The ability to burst depends on whether bandwidth is available. CIR may also be negotiated as variable over time, so that during busy business hours more bandwidth is available.

Basically, CIR is the throughput rate that you negotiate with a service provider, and they will usually attempt to guarantee that rate. One way the carrier guarantees CIR is by dropping non-CIR traffic.

Carriers will often "overbook" the capacity of their networks, hoping that customers will not make excessive demands on the network at the same time. But if the carrier miscalculates, traffic will be dropped, even if it is guaranteed, although non-CIR traffic will be dropped first.


Read this one also;

Reference: http://en.wikipedia.org/wiki/Committed_Information_Rate


Actually, FRAME RELAY is a LAYER 2 service. In the IP traffic, IP packets are encapsulated by the FRAME RELAY frames. The encapsultion is removed upon reaching its destination or reprocess by another LAYER 2 device or system. ATM traffic also employs CIR. The main feature involved in making CIR possible is the DISCARD ELIGIBLE (DE) bit in the frame. Read below;

Reference: http://www.cisco.com/en/US/docs/internetwo....html#wp1020632


For DSL services, CIR is not being really being implemented. The CIR bla bla bla in your application form is just a marketting strategy.

What's usually applied is bandwidth limit or capping. This can be easily done.

To sum it up, if you paid for a particular CIR and you cant get it even on off-peak hours (late night until 8 AM), and your ISP technicians keep saying the line is okay, .... then find another ISP.

Usually, ISPs at its distribution area level are too oversubscribed.

Also, ..

Data portion is your Internet traffic. This traffic maybe bundled with voice traffic or others and this combined traffic is now determined by your CIR.