Nortel Networks WEB OS 212777 - Manual (Page 445)

Web OS 10.0 Application Guide
Chapter 17: Bandwidth Management n 445
212777-A, February 2002
Rate Limits
A bandwidth policy specifies three limits, listed and described in Table 17-1 :
Bandwidth Policy Configuration
Each bandwidth policy, comprised of the reserved, soft, and hard limits, is assigned an index.
These policies can be found under the
/cfg/bwm menu. Up to 64 bandwidth policies can be
defined. Bandwidth limits are usually entered in Mbps.
N OTE – For better granularity, rates can be entered in Kbps by appending “K” to the entered
number. For example, 1 Mbps can be entered as either “1” or as “1024k.”
Table 17-2 lists the granularity of policy limits:
In addition, a queue size is associated with each policy. The queue size is measured in bytes.
Table 17-1 Bandwidth Rate Limits
Rate Limit Description
Committed Information
Rate (CIR)
or Reserved Limit This is a rate that a bandwidth classification is always guaranteed. In con-
figuring BWM contracts, ensure that the sum of all committed informa-
tion rates never exceeds the link speeds associated with ports on which
the traffic is transmitted. In a case where the total CIRs exceed the out-
bound port bandwidth, the switch will perform a graceful degradation of
all traffic on the associated ports.
Soft Limit This is the desired bandwidth rate, that is, the rate the customer has
agreed to pay on a regular basis. When output bandwidth is available, a
bandwidth class will be allowed to send data at this rate. No exceptional
condition will be reported when the data rate does not exceed this limit.
Hard Limit This is a “never exceed” rate. A bandwidth class is never allowed to trans-
mit above this rate. Typically, traffic bursts between the soft limit and the
hard limit are charged a premium. The maximum hard limit for a band-
width policy is 1 Gbps, even when multiple Gigabit ports are trunked.
Table 17-2 Bandwidth Policy Limits
Bandwidth Range Interval Bandwidth Range Interval
250 Kbps to 5000 Kbps 250 Kbps 50 Mbps to 150 Mbps 10 Kbps
1 Mbps to 20 Mbps 1 Mbps 150 Mbps to 500 Mbps 25 Mbps
20 Mbps to 50 Mbps 5 Mbps 500 Mbps to 1000 Mbps 50 Mbps