Chapter 12 Port Rate Limit and Storm Control

Table 22 Rate Limit and Storm Control (continued)

LABEL

DESCRIPTION

Ingress Rate

Displays the maximum bandwidth allowed in kilobits per second (Kbps) for the

 

incoming traffic flow on a port.

 

 

Egress Rate

Displays the maximum bandwidth allowed in kilobits per second (Kbps) for the out-

 

going traffic flow on a port.

 

 

12.1.1 Rate Limit Screen

Click a port number in the Port Rate screen to bring up the screen as shown next.

Figure 43 Rate Limit Configuration

The following table describes the related labels in this screen.

Table 23 Rate Limit Configuration

LABEL

DESCRIPTION

Ingress Rate

Specify the maximum bandwidth allowed in kilobits per second (Kbps) for the incoming

 

traffic flow on a port.

 

 

Egress Traffic

Select Disabled to not have any bandwidth limits for outgoing traffic on the port or

Shaping

select Enabled to enable bandwidth limits for outgoing traffic on the port.

 

 

Rate

This is a read only field indicating the rate limit of outgoing traffic on the port in Kbps.

 

This value changes depending on the number of Tokens Added Per Interval.

 

 

Tokens

The switch uses a “Token Bucket” algorithm to limit the outgoing rate on the ports and

Added Per

to limit the largest amount of packets that can leave the port in any one instance.

Interval

In this algorithm each “token” represents an allowed amount of bandwidth to be sent

 

out on the port.

 

The “bucket” holds the tokens. In other words, the number of tokens in the bucket

 

represents the maximum allowed bandwidth to go out on the port. The size of the

 

bucket is specified by the “burst size” (see below).

 

Every time traffic goes out on the port, tokens (representing used up bandwidth) are

 

removed from the bucket, thus limiting the amount of traffic allowed to go out on the

 

port. Tokens are also added to the bucket every Token Update Interval, thus

 

resetting the amount of bandwidth allowed to go out. If the bucket is empty, the data

 

packets are dropped until more tokens are added to the bucket.

 

Select the number of tokens that should be added to the bucket per Token Update

 

Interval. Each token represents .5 bit in bandwidth allowed to go out on the port.

 

 

80

 

ES-1528 User’s Guide