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2.1.4.2 Upstream QoS
In the upstream direction, for each T-CONT the ingress traffic in the ONT passes by a mapping block that maps the traffic in one of the eight queues
according with the p-bit, these queues have a Strict Priority Scheduler. The ONT “waits” until the OLT assigns a transmission timeslot for that T-
CONT, so that the most prioritized queues are the ones that transmit first. In the OLT ingress, the traffic is put into a queue according with what
is defined in the queue/p-bit mapping. Each of these queues has an associated scheduler and policer that control the traffic sent to the uplink.
Figure 2-9: Upstream QoS Diagram
2.1.4.3 Dynamic Bandwidth Allocation (DBA)
The DBA (Dynamic Bandwidth Allocation) is available in order to optimize the upstream bandwidth. This mechanism consists in defining an ad-
equate T-CONT to the service traffic in question. There are five types of T-CONT, defined by the Fixed, Assured and Maximum Parameters:
Type 1: Only fixed Bandwidth;
Type 2: Only Assured Bandwidth;
Type 3: Maximum Bandwidth;
Type 4: Only Maximum Bandwidth (Best Effort);
Type 5: Fixed+Maximum Bandw
T-CONT Type 1 Type 2 Type 3 Type 4 Type 5 Units
Fixed BW- R
F
R
F1
0 0 0 R
F5
[b/s]
Assured BW- R
A
0 R
A2
R
A3
0 R
A5
[b/s]
Max Bw - R
M
R
M1
= R
F1
R
M2
= R
A2
R
M3
> R
A3
R
M4
R
M5
>
R
F5
+ R
A5
[b/s]
Bandwidth Eligi-
bility
0 0 Non-Assured
BW - R
NA
Best-Effort
- R
BE
R
NA
/ R
BE
Table 2-1: T-CONT types definition
In each GPON interface there is 1024 Alloc-ID (T-CONT identifiers) available, provided to manage ONT services. They are distributed in the follow-
ing way: