# What is CBS and EBS?

## What is CBS and EBS?

1. Specifies the maximum number of bits allowed for incoming Service Frames to be EIR-conformant; for every connection, an EBS is defined. It is also defined as the maximum number of bits in excess of the Committed Burst Size (CBS) that a user can send during a predefined time period.

### What is cir0?

Some Frame Relay vendors offer inexpensive services with a CIR equal to zero. This essentially means that the network will deliver as many frames as it can, but it doesn’t guarantee any bandwidth level.

#### How is excess information rate calculated?

Excess information rate (EIR) is the magnitude of the burst above the CIR (PIR = EIR + CIR). Maximum information rate (MIR) in reference to broadband wireless refers to maximum bandwidth the subscriber unit will be delivered from the wireless access point in kbit/s.

How is committed burst size related to committed information rate?

The mean rate is specified in bits per sec or bytes per sec as IP packets are of variable lengths. Committed burst size (CBS) specifies the maximum number of bytes that can be transmitted into the network in an extremely short interval of time. Time interval (T) specifies the time per burst.

How is CBS calculated?

CBS = CIR (in bytes) /4 = (16 *1024 /8) / 4 = 512 KBytes. So CBS comes out to be 512 KBytes which can be set for the traffic.

## What is excess burst?

The excess burst size (Be) specifies how much data above the committed burst size (Bc), a user can transmit. While CIR deals with the long-term traffic load of an interface (or PVC), excess burst size determines the initial size of a transaction that the network can support.

### What is CIR bandwidth?

In a Frame Relay network, committed information rate (CIR) is the bandwidth for a virtual circuit guaranteed by an internet service provider to work under normal conditions. The bandwidth is usually expressed in kilobits per second (kbit/s).

#### How is burst size calculated?

Calculating burst size

1. Take the FREE phage average of the time points on the plateau before the burst (A)
2. Take the FREE phage average of the time points on the plateau after the burst (B)
3. Subtract A from B; This is the total burst or new phages released (C)

What is CBS value?

During rate limiting configuration, the committed information rate (CIR) and committed burst size (CBS) need to be set. The CIR is the guaranteed average transmission rate, and the CBS is the average volume of burst traffic that can pass through an interface. The default CBS value is 125 times the CIR.

What is burst size limit?

The maximum burst size is the maximum number of bytes a router can absorb without dropping a packet. This is determined by the size of the router queue, and by the current cross traffic at that router.

## How is contention ratio calculated?

A contention ratio is how much bandwidth you have versus how much you have sold. For example, you might have a 1000Mbps internet link, but you have have 24x 100Mbps connections on it. That gives a contention of (24*100):1000, or 2.4:1.