Network Router User Manual

11
ATM-based QoS
The ATM-based QoS takes advantage of the fine-
grained segmentation into ATM cells, further minimizing
latency and jitter. This ATM-based QoS can be
combined with packet-based QoS.
In the traditional setup, there is a fixed relation between
PVCs and VLANs for traffic separation. The VLANs are
differentiated by priority and the IP DSLAM is
configured to map the traffic in a specific VLAN to
specific PVC configured with the relevant service class.
Upstream traffic can be classified based on:
• End-user PVC
• DSCP
Downstream traffic is distributed to PVCs based on a
combination of service VLANs and p-bit.
EDA 1200 thereby supports multiple services within a
single service VLAN to be mapped into multiple PVCs
based upon Ethernet Class-of-Service (p-bit).
QoS within single PVC (EDN312)
The IP DSLAM also supports multiple traffic classes
(services) within the PVC, allowing the access provider
to support multiple services from a single gateway.
Quality of Service within a single PVC is a highly flexible
feature that can be supplemented with other PVCs for
traffic separation, e.g. between company VPN and a
private triple play access on the same DSL line.
Overload Protection (EDN312)
On the receiver side of the Ethernet and ADSL
interfaces, the IP DSLAM implements mechanism to
secure prioritized packet handling in situations where
the traffic load exceeds the packet processing
performance of the IP DSLAM. Ethernet Overload
Protection (EOP) and ADSL Overload Protection (AOP)
are common for all lines in the IP DSLAM, and secures
that high prioritized traffic is processed (e.g. voice and
video) before best-effort traffic such as Internet surf in a
packet overload situation.