10
Traffic mapping
End-user traffic is mapped to service VLANs. These
VLANs may be end-user specific or common to multiple
end-users. Through such VLANs a single or multiple
application services, e.g. voice, video or data, may be
accessible.
The traffic mapping to service VLAN may be based on:
•
PVC or PVC bundle
•
VLAN
•
Line
•
Ethertype
On each end-user line, EDA 1200 allows for
configuration of up to eight individual PVC or VLAN
based traffic mapping definitions (maximum 72 PVC
based mapping definitions in total per EDN312).
Quality of Service
In order to provide the required Quality of Service (QoS)
for the various triple play service classes (voice, video
and data), all EDA nodes support prioritization of
Ethernet frames in accordance with the IEEE 802.1Q
specification.
The EDA 1200 IP DSLAMs also supports a number of
advanced QoS and scheduling features for fine-tuning
the network performance:
•
Packet-based QoS
−
Queuing and scheduling
−
PTM principles
−
PTM QoS mapping downstream traffic
•
ATM-based QoS for ADSL2+/ADSL2/ADSL
−
Separation of traffic classes into PVCs
−
Traffic processing according to priority (packet
based queuing)
−
EDN312 overload protection; ensuing high priority
traffic handling during high load situations
Packet based queuing and scheduling
IEEE 802.1 p-bit based traffic distribution is performed
towards a structure of queues (per end-user).
Scheduling from these queues can be performed as
strict priority, deficit round-robin or modified deficit
round-robin. Using these scheduling methods enables
optimization towards high priority traffic and/or fair
bandwidth division between traffic classes.
PTM for VDSL2 - Principles
With VDLS2 on the EDN612 Packet Transmission Mode
(PTM) is introduced instead of ATM. In short, PTM
allows direct transmission of Ethernet packets on the
DSL line, by segmenting the line capacity into two
latency paths — a fast path and an interleaved path. The
two paths are individually configured and will typically
be utilized for separation of different types of services.
In addition to a somewhat simplified operation
compared to ATM, PTM will also reduce transmission
overhead by up to10%.
PTM QoS mapping
Upstream PTM Quality of Service mapping can be
based on:
•
P-bit
•
DSCP
•
VLAN
The service mapping function keeps the relationship
between service VLANs and end-user VLANs, replacing
the VLAN from the end-user with the corresponding
service VLAN in the upstream direction, and vice-versa
in the downstream direction.
The Queuing and scheduling function uses the VLAN
and Ethernet Class-of-Service (p-bit) setting to
determine the appropriate queue and latency path for
each specific packet. As each latency path (like PVCs in
the ATM-world) is a limited resource in terms of
bandwidth, the schedulers handle bandwidth utilization.
