Table 13: Effective Rate Limit - Edge-Core ECS3510-26P Management Manual

| Congestion Control
C 9
HAPTER
Rate Limiting
For example, a Gigabit port has a 10 ms window size, so there are 100
scales per second, each scale having a bandwidth of 10 Mbps, and
using an inter-packet gap of 20 bytes.
Therefore, when the rate limit is set at 64 kbit/s, each scale has a
shared bandwidth of 80 bytes.
When the packet size = 64 bytes, and the gap = 20 bytes,
each packet = 84 bytes > 80bytes. Only one packet can pass through
in each scale. One second has 100 scales, so the rate is 100 packets
per second.
When the packet size = 640 bytes, and the gap = 20 bytes,
each packet = 660 bytes > 80 bytes. The switch will only let one packet
pass in each scale, so there are still 100 packets per second.
When the packet size = 1500 bytes, and the gap = 20 bytes,
each packet = 1520 bytes > 80 bytes. The switch will only let one
packet pass in each scale, so there are still 100 packets per second.
The following table shows the actual number of packets received when
various ingress rate limits are applied to packets of different sizes. The
values shown below were measured for both ingress rate limiting and
storm control functions.

Table 13: Effective Rate Limit

Packet Size Rate Limit
64 bytes 64 kbit/s
128 kbit/s
256 kbit/s
512 kbit/s
1024 kbit/s
2048 kbit/s
128 bytes 64 kbit/s
128 kbit/s
256 kbit/s
512 kbit/s
1024 kbit/s
2048 kbit/s
512 bytes 64 kbit/s
128 kbit/s
256 kbit/s
512 kbit/s
1024 kbit/s
2048 kbit/s
– 228 –
Packets Received
100
200
400
800
1600
3105
100
100
300
500
900
1800
100
100
100
200
300
500