User guide

Traffic Management Connection Admission Control (CAC)
Telesyn Service Guide (Ethernet Passive Optical Network (EPON))
6-2
At points outside the OLT-ONU, p-bits/classifiers may still used at various points; moreover, these are passed
through the OLT-ONU. This has the following results:
• In the upstream direction, traffic is passed with no controls from the UNI to the ONU. From the OLT to the
ONU, the SLA is used to prioritize traffic flows per VLAN as follows:
• High - UPDELAYSENSITIVITY=Sensitive
• Medium - UPDELAYSENSITIVITY=Tolerant, MINUPSTREAMRATE not=0
• Low - MINUPSTREAMRATE=0
At the EPON interface, p-bits may be used with the VPRIORITY setting to separate and prioritize traffic for
up to 8 queues.
Note: The user must be sure that there are no conflicts between the flows set up by the SLA and
those by the p-bit settings, since they are separate traffic management tools.
• In the downstream direction, p-bits/classifiers are set at the EPON interface. For known unicast traffic (non-
video and non-BRUUM), the SLA per VLAN is used to prioritize the data flows. At the ONU, the p-bit/clas-
sifier settings are passed down to the ONU and are actually applied to the traffic flows.
Note: Traffic management is therefore not performed by the EPON but by the ONU, which has the
interface to the UNI. The ONU is modeled as an Telesyn extension.
6.2.3 Connection Admission Control (CAC)
The CAC function is to ensure the hardware can provide the guarantees configured by the SLAs. There are two
type of CAC check on the EPON2 interface:
1. Sum of Minimum Bandwidths - The sum of provisioned minimum bandwidths for the QOSPOLICYs of all
logical links on an EPON port must not exceed the bandwidth capacity of that port in either upstream or
downstream direction. This limit is slightly below 1G due to administrative overhead (REPORTs, GRANTs,
OAMPDUs, etc.). This function is performed in OAM so that CAC can be enforced even if the EPON2 card
is not physically present (i.e. when pre-provisioning).