Management and Configuration Guide K/KA/KB.15.15

NOTE: Rate-limiting is applied to the available bandwidth on a port and not to any specific
applications running through the port. If the total bandwidth requested by all applications is less
than the configured maximum rate, then no rate-limit can be applied. This situation occurs with a
number of popular throughput-testing applications, as well as most regular network applications.
Consider the following example that uses the minimum packet size:
The total available bandwidth on a 100 Mbps port "X" (allowing for Inter-packet
Gap-IPG), with no rate-limiting restrictions, is:
(((100,000,000 bits) / 8 ) / 84) × 64 = 9,523,809 bytes per
second
where:
• The divisor (84) includes the 12-byte IPG, 8-byte preamble, and 64-bytes of
data required to transfer a 64-byte packet on a 100 Mbps link.
• Calculated "bytes-per-second" includes packet headers and data. This value
is the maximum "bytes-per-second" that 100 Mbps can support for
minimum-sized packets.
Suppose port "X" is configured with a rate limit of 50% (4,761,904 bytes.) If a
throughput-testing application is the only application using the port and transmits
1 Mbyte of data through the port, it uses only 10.5% of the port's available
bandwidth, and the rate-limit of 50% has no effect. This is because the maximum
rate permitted (50%) exceeds the test application's bandwidth usage
(126,642-164,062 bytes, depending upon packet size, which is only 1.3% to
1.7% of the available total.) Before rate-limiting can occur, the test application's
bandwidth usage must exceed 50% of the port's total available bandwidth. That
is, to test the rate-limit setting, the following must be true:
bandwidth usage (0.50 × 9,523,809)
ICMP rate-limiting
As of software version K.15.02.0004, ICMP rate-limiting and classifier-based-rate-limiting operates
on the entire packet length instead of just the IP payload part of the packet. As a result, the effective
metering rate is now the same as the configured rate. The rate-limiting applies to these modules:
Minimum supported
software version
Product numberHP device
K.15.02.0004J9534AHP Switch 24-port 10/100/1000 PoE+ v2 zl Module
K.15.02.0004J9535AHP Switch 20-port 10/100/1000 PoE+ / 4-port SFP v2 zl Module
K.15.02.0004J9536AHP Switch 20-port 10/100/1000 PoE+ / 2-port 10-GbE SFP+ v2
zl Module
K.15.02.0004J9537AHP Switch 24-port SFP v2 zl Module
K.15.02.0004J9538AHP Switch 8-port 10-GbE SFP+ v2 zl Module
K.15.02.0004J9547AHP 24-port 10/100 PoE+ v2 zl Module
K.15.02.0004J9548AHP 20-port Gig-T / 2-port 10-GbE SFP+ v2 zl Module
K.15.02.0004J9549AHP 20-port Gig-T / 4-port SFP v2 zl Module
K.15.02.0004J9550AHP 24-port Gig-T v2 zl Module
K.15.02.0004J9637AHP 12-port Gig-T / 12-port SFP v2 zl Module
In IP networks, ICMP messages are generated in response to either inquiries or requests from
routing and diagnostic functions. These messages are directed to the applications originating the
186 Port Traffic Controls