Alteon Application Switch Operating System Application Guide
Bandwidth Management
768
Document
ID:
RDWR-ALOS-V2900_AG1302
A bandwidth policy specifies four limits, listed and described in
Table 67 - Bandwidth Rate Limits,
:
Application Session Capping
Application session capping is a feature that allows limits to be placed on the number of sessions on
a user per contract or per contract basis. This results in bandwidth contracts having an additional
maximum sessions parameter that will define the upper limit at which the application will be capped.
Note:
Session capping per contract is applied on a per SP basis. Session capping per-user is applied
on a per-Alteon basis.
Application session capping is applied in the following ways:
•
Contract Capping—Session capping per contract is applied per SP.
•
User Capping—Session capping per user is applied.
Table 67: 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
configuring BWM contracts, ensure that the sum of all committed
information rates never exceeds the link speeds associated with ports on
which the traffic is transmitted. If the total CIRs exceed the outbound port
bandwidth, Alteon performs a graceful degradation of all traffic on the
associated ports.
Soft limit
For traffic shaping contracts, 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 is allowed to send data at this
rate. No exceptional condition is reported when the data rate does not
exceed this limit. For rate limiting contracts, the soft limit is ignored.
Hard limit
This is a "never exceed" rate. A bandwidth class is never allowed to
transmit above this rate. Typically, traffic bursts between the soft limit and
the hard limit are charged a premium. The maximum hard limit for a
bandwidth policy is 1 Gbps, even when multiple gigabit ports are trunked.
To ensure a specific amount of throughput on a port, configure hard and
soft limits close together. For example, to ensure 20 Mbps of throughput on
a 100 Mbps port, create a policy on a contract that sets the hard limit to
20M and the soft limit to 19M. If you apply this contract to a filter on the
egress port, 20 Mbps of throughput can be ensured.
User limit
A user limit is a hard limit rate for individual users. It is defined as a policy
and is applied and enabled for an individual contract. It is based on either a
source IP or destination IP address. Setting user limits requires that a
contract be configured that enables IP limiting (
/cfg/bwm/cont
<x>
/
iplimit ena
), and sets the type of limiting to source IP or destination IP
address (
/cfg/bwm/cont
<x>
/iptype {sip|dip}
).
When configured, an individual IP address can be limited to traffic between
0 kbps and 1000 Mbps. A user limit based on source IP address should be
set if the goal is to limit the amount of data being transmitted from a
source IP address in your network.
A user limit based on the destination IP address should be set if the goal is
to limit the amount of data being downloaded from a destination IP address
in your network.
