CoS port groups provide for grouping ports by CoS feature configuration and port type. Ports are required to be configured by groups: this feature provides a meaningful way of identifying ports by similar functionality and port type.
Groups consist of a group number and port type and are numbered as such, port-group.port-type. For example: port group 0, port type 0 would be numbered port group 0.0. Three default port groups exist for TxQ, IRL, ORL, and flood control CoS features and are identified as port group 0 and port type 0 or 1 and are indexed as 0.0 or 0.1 respectively for each feature (Port type 1 is not supported on the 7100-Series). These default port groups cannot be removed and all physical ports in the system are assigned to one of the three port groups for each feature (remember group assignment is determined by port type).
Additional port groups, up to eleven total, may be created. Ports assigned to a new port group cannot belong to another non-default port group entry and must be comprised of the same port type as defined by the port group you are associating it with. The creation of additional port groups could be used to combine similar ports by their function for flexibility. For instance, ports associated to users can be added to a port group called Users and ports associated to uplink ports can be added to a port group called Uplink. Using these port groups, a class of service unique to each group can assign different rate limits to each port group. User ports can be assigned a rate limit configured in one CoS, while Uplink ports can be assigned a different rate limit configured in another CoS. A maximum of 8 port groups per CoS transmit queue and/or rate-limiter function are supported.