These OVC attributes are assigned per ENNI, i.e. if an OVC has end-points on more than one ENNI, these attributes can have different values on each of them.
1. OVC End Point Identifier
The OVC End Point Identifier is a string of up to 45 bytes administered by the Operator that is used to identify an OVC End Point within a given CEN. The OVC End Point Identifier is not carried in any field in the ENNI Frame. It must be unique to all OVC end points in the CEN.
2. Class of Service (CoS) ID
A Class of Service Identifier is a set of one or more S-Tag PCP values. Each Class of Service Identifier indicates a single Class of Service instance. The Class of Service that applies to an ingress S-Tagged ENNI Frame that is mapped to the OVC End Point is the Class of Service identified by the Class of Service Identifier that contains the S-Tag PCP value in the frame.
For example, the S-Tag PCP values 0, 1, 2, and 3 could constitute a Class of Service Identifier that indicates the silver service while the S-Tag PCP values 4, 5, 6, and 7 could constitute a Class of Service Identifier that indicates the gold service. In this example, an S-Tagged ENNI Frame with S-Tag PCP value = 3 would be given the silver service. Note that in case of S-tag bundling, the map is independent of the S-VLAN ID. The following rules apply:
- Each PCP value must be mapped to exactly one COS ID
- One CoS ID can be set to 100% discard
- CoS ID can have different maps between different OVC end points, as long as they are associated with different OVCs
Frame color can be marked in one of two methods: DEI bit or S-tag PCP values. According to MEF 23, the following values are recommended for a 3 CoS model.
For green color or when color is marked using DEI bit:
For yellow color or when color is marked using PCP bits:
3. Ingress Bandwidth Profile
An Ingress Bandwidth Profile (BWP) can be applied per OVC end point or per CoS ID per OVC End point per ENNI. Note that each ingress ENNI frame can be subject to at most one BWP.
As with bandwidth profiles at the UNI, the OVC bandwidth profiles are implemented with two-rate three-color policers that determine conformance to the profile. Green frames are forwarded and are subject to all guarantees of the Service Level Specification, yellow frames are forwarded but not subject to the SLS, and red frames are dropped.
Ingress BWP per OVC End Point is just like the Ingress BWP per UNI. It is used to enforce a rate limit into the network over an external interface.
The figure at right depicts ingress BWP per OVC end point.
Each Ingress BWP must include suitable parameters <CIR, CBS, EIR, EBS, CF, CM>. At the ENNI, CM must be set to color aware.
4. Egress Bandwidth Profile
The Egress Bandwidth Profile per OVC End Point describes egress policing by the Operator on all egress ENNI Frames that are mapped to a given OVC End Point.
An Egress Bandwidth Profile (BWP) can be applied per OVC end point or per CoS ID per OVC End point per ENNI.
Each Egress BWP must include suitable parameters <CIR, CBS, EIR, EBS, CF, CM>. CM must be set to color aware.
Note that each egress ENNI frame can be subject to at most one BWP.
