3.4.1 Bandwidth monitoring

This function monitors the frame length (from MAC addressto FCS) of the frame detected by flow detection or the bandwidth based on the frame count. Frames that are forwarded as being within the specified monitoring bandwidth are referred to as compliant frames. Frames penalized for exceeding the monitoring bandwidth are referred to as non-compliant frames.

Token Bucket algorithms are used to determine whether a frame detected by flow detection complies with or violates the monitoring bandwidth.

Burst size is the maximum frame capacity that can forward burst traffic as compliance frames. The following table describes the characteristics of burst sizes.

Table 3-5: Features of burst size

Burst size	Features
Smaller	The dropping of burst traffic is relatively easy. If traffic is sent while communication is not being performed, the send bandwidth fluctuations are relatively small.
Larger	The dropping of burst traffic is relatively difficult. If traffic is sent while communication is not being performed, the send bandwidth fluctuations are relatively large.

The bandwidth monitoring functionality consists of minimum bandwidth monitoring and maximum bandwidth control. The following table describes the types of penalties that can be used for minimum bandwidth monitoring and maximum bandwidth control.

Table 3-6: Types of penalties that can be used for minimum bandwidth monitoring and maximum bandwidth control

Penalty for non-compliant frames	Type of bandwidth monitoring
	Minimum bandwidth monitoring	Maximum bandwidth control
Discard	-	OK
Queuing priority change	OK	-
DSCP updating	OK	-

DSCP rewrite penalty does not operate for the following frames:

• IPv4 and IPv6 packets exceeding the MTU

• Frames whose TTL is set to 1

• Frames whose hop limit is set to 1

• Frames with an IP option

• Frames with an IPv6 extension header

• IPv4 or IPv6 packets with an unknown receiver address