4.1.4 Port bandwidth control

The port bandwidth control functionality shapes the traffic to the send bandwidth specified for the relevant port after scheduling is performed. You can use this control to connect to wide-area Ethernet services.

For example, if the line bandwidth is 1 Gbit/s and the contract bandwidth with the ISP is 400 Mbit/s, you can use port bandwidth control to suppress the bandwidth to 400 Mbit/s or less when sending frames.

Port bandwidth control uses the leaky bucket algorithm, which is based on the model of a bucket that has a hole in the bottom.

The tables below describe the setting range for port bandwidth control. Set the bandwidth so that it is equal to or smaller than the line speed. If setting is not possible, the operation log is displayed, and the port bandwidth control setting is disabled.

Table 4-8: Scope of port bandwidth control settings (10BASE-T,100BASE-TX,1000BASE-T,1000BASE-X)
Setting unit #1	Setting range	Increment
Gbit/s	1G	1 Gbit/s
Mbit/s	1M~1000M	1Mbit/s
kbit/s	1000~1000000	100kbit/s^#2
kbit/s	64~960	64kbit/s^#3

#1: 1G is treated as 1000000000, 1M is treated as 1000000, and 1k is treated as 1000.

#2: To set a value of 1000 kbit/s or more, specify the value in units of 100 kbit/s (1000, 1100, 1200...1000000).

#3: To set a value less than 1000 kbit/s, specify the value in units of 64 kbit/s (64, 128, 192...960).

Table 4-9: Scope of port bandwidth control settings (10GBASE-R,10GBASE-T)
Setting unit #1	Setting range	Increment
Gbit/s	1G~10G	1 Gbit/s
Mbit/s	1M~10000M	1Mbit/s
kbit/s	1000~10000000	100kbit/s^#2
kbit/s	64~960	64kbit/s^#3

#1: 1G is treated as 1000000000, 1M is treated as 1000000, and 1k is treated as 1000.

#2: To set a value of 1000 kbit/s or more, specify the value in units of 100 kbit/s (1000, 1100, 1200...10000000).

#3: To set a value less than 1000 kbit/s, specify the value in units of 64 kbit/s (64, 128, 192...960).

Table 4-10: Scope of port bandwidth control settings (40GBASE-R)
Setting unit #1	Setting range	Increment
Gbit/s	1G~40G	1 Gbit/s
Mbit/s	1M~40000M	1Mbit/s
kbit/s	1000~40000000	500kbit/s^#2
kbit/s	256~768	256kbit/s^#3

#1: 1G is treated as 1000000000, 1M is treated as 1000000, and 1k is treated as 1000.

#2: To set a value of 1000 kbit/s or more, specify the value in units of 500 kbit/s (1000, 1500, 2000...40000000).

#3: To set a value less than 1000 kbit/s, specify the value in units of 256 kbit/s (256, 512, 768).

Table 4-11: Scope of port bandwidth control settings (100GBASE-R)
Setting unit #1	Setting range	Increment
Gbit/s	1G~100G	1 Gbit/s
Mbit/s	1M~100000M	1Mbit/s
kbit/s	1000~100000000	500kbit/s^#2
kbit/s	512	512kbit/s^#3

#1: 1G is treated as 1000000000, 1M is treated as 1000000, and 1k is treated as 1000.

#2: If the setting is 1000k or more, specify in 500k increments (1000, 1500, 2000,..., 100000000).

#3: If the setting is less than 1000k, specify only 512.

The following table describes the setting range for the burst size.

Table 4-12: Range of burst size settings
Line type	Setting range	Default value when no value is specified
10BASE-T 100BASE-TX 1000BASE-T 1000BASE-X 10GBASE-R 10GBASE-T	4, 8, 16, 32 KB	32 KB
40GBASE-R	8, 16, 32, 64kbyte	64kbyte
100GBASE-R	16, 32, 64, 128kbyte	128kbyte

The following table describes the burst size characteristics based on the properties of the leaky bucket algorithm.

Table 4-13: 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 part of a frame to which port bandwidth control applies is from the MAC header to the FCS. The following figure shows the part of the frame to which port bandwidth control applies.

Figure 4-3: Scope of port bandwidth control