User's Manual

FiberGateway

Figure 9: Dowstream QoS diagram

In the downstream direction, Figure 9, the ingress traffic can be firstly classified. It passes by a policer

and is configured to each ONT service, which is defined by one or two tags. It is remarked and policed

per-CoS rate (port profile).

After this, Network services (per VLAN) classification determine the PON port queue where packets will

wait for a transmission opportunity, and can remark the CoS (P-bits in VLAN PCP). The traffic is put in

a queue according with the p-bit/DSCP->Traffic Class mapping.

Each of these Traffic Classes is associated with a scheduler (WRR or SP) and a policer.

Queue congestion management is used to prevent the queue from overflowing and is performed based

on Tail Drop or WRED.

Each queue is served by either a priority or weighted scheduler and rate controlled.

Then Traffic Classes to P-bit remarking is done and the traffic flows to the GPON interface.

Destination ONU/ONT client service downstream profile defines traffic classless policing. The overall

PON port may be limited to a percentage of its capacity.

Traffic arriving to the ONU/ONT it will pass by a mapping block which will map the traffic in one of the

eight queues according with the p-bits; these queues have a Strict Priority scheduler in order to

guarantee that the most prioritized traffic passes first, Figure 10: Upstream QoS diagram

2.6.2 Upstream QoS

In the upstream, Figure 11: Traffic distribution by service/client

, for each T-CONT DBA 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, (in case the ingress traffic is untagged a DSCP->p-

bit mapping is performed).

These queues have a Strict Priority Scheduler. Packets are stored at the intended T-CONT priority

queue, which is scheduled according to ONT configuration.

The ONT “waits” until the OLT assigns a transmission timeslot for that T-CONT, according to DBA, so

that the most prioritized queues are the ones that transmit first.

In the OLT PON ingress port, traffic is remarked and can be policed per-CoS. The traffic is put into a

Traffic Class according with what is defined in the p-bit/DSCP->queue mapping.