User guide

EDA System Services
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an overload protection mechanism that is always active. In order to be able
to limit the traffic from an End-user, policing can be applied on the traffic
per PVC, per CoS flow or both. Figure 41 on page 57 illustrates the QoS
and bandwidth control mechanisms in the IP DSLAM.
Ethernet
Packet
based
queuing
and (optionally)
policing
IP DSLAM
Downstream traffic
overload
protection
ATM
prioritization
PVC
mapping
Ethernet
PVC
Policing
(optional)
IP DSLAM
CoS Flow
Policing
(optional)
Overload
protection
VLAN
Mapping
and
Classification
Upstream traffic
Figure 41 QoS and Bandwidth Control Mechanisms
The policing imposed by the IP DSLAM is not a traditional policing.
Traditional policing discards all packets that exceed the configured
bandwidth. However, this property is very unfortunate for TCP traffic, which
is a burst traffic by nature, and has a self-adjusting mechanism. The EDA
policing therefore, allows the operator to configure an extra bandwidth
(burst size) that will be allowed to pass for a short period of time.
Since there are different mechanisms in the upstream and downstream,
they will be explained separately.
6.3.1 Downstream Mechanisms
Figure 42 on page 58 illustrates the flow of the traffic in the downstream
direction.