Requested revision
| Standard: | 802.1Q-2011 | Clause: | 6.11.2 |
| Clause title: | Support of the EISS by Customer Backbone Ports | ||
Rationale for revision
The specification in c6.11.2 specifies:
?The priority and drop_eligible parameters carry the same value as the corresponding parameter in the EISS request.?
This implies that the c6.11 function?s ISS SAP priority and drop_eligible parameters carry the BVLAN priority and drop_eligible parameter values. Those BVLAN related priority/drop_eligible parameter values are then used to control the c8.6.6 Queueing of BSI frames.
When the CBP contains clause 6.18 functions (around BSI MEP/MIP functions) the clause 6.18's ISS SAP priority and drop_eligible parameter values are based on the BSI priority and drop_eligible parameter values (and not longer on the BVLAN's values).
The behaviour is as such not consistent.
The BVLAN however is terminated and the BSI signals are forwarded over the ISS SAP. The ISS SAP priority and drop_eligible parameters should therefore be based on the BSI priority and drop_eligible parameter values. The c8.6.6 Queueing of BSI frames should be controlled by the BSI priority/drop_eligible parameters.
Proposed text
Add to 6.11.2 the specification to read the I-PCP and I-DEI fields and then use the c6.11.3 function to determine the ISS SAP?s _priority and drop_eligible parameter values.
Replace the following paragraph in 6.11.2:
"The priority and drop_eligible parameters carry the same value as the corresponding parameter in the EISS request."
by
"The value of the drop_eligible and priority parameters are determined as follows:
g) The value of the drop_eligible parameter and the received_priority value are decoded from the I-DEI and the I-PCP fields of the I-TAG in the mac_service_data_unit as described in 6.11.3."
Impact on existing networks
Existing CBPs without clause 6.18 functions (located around BSI MEP and/or MIP functions) will perform their Queueing frame function on the BVLAN priority/drop_eligible parameter values which may not be the same as the BSI priority/drop_eligible parameter values. Under I-Tagged LAN congestion conditions, an incorrect set of BSI frames may be forwarded.
Originator
| Name: | Maarten Vissers | Email: | maarten.vissers@huawei.com |
| Affiliation: | Huawei | ||
| Submitted: | 2012-01-16 | ||