Requested revision
Standard: | 802.1Qbg-2012 | Clause: | multiple clauses stated in the following text |
Clause title: | multiple clauses |
Rationale for revision
The R field of EVB TLV is the maxRetries value for ECP state machine (43.3.7.4).
Most system variables for R are named with "maxRetries" suffix, but some variables are named with "maxTries", and the ECP Tx state machine (43.3.4) is designed with "maxTries" in mind.
For example, in the ECP Tx state machine, ECPDU can be sent maximum 3 times when "maxRetries = 3", although ECPDU should be sent up to 4 times (1 + maxRetries). Also, if "maxRetries = 0" (which is valid value for R) and no ack was received, state transition from "transmitECPDU" fails.
So, the ECP Tx state machine should be modified to correctly reflect the meaning of "maxRetries". Additionally, several system variables such as evbSysEcpDfltMaxTries (Table 12-17 and Table 12-18 of 12.26.1), ecpAdminMaxTries (Table 12-18 of 12.26.1) and ecpOperMaxTries (12.27.1, 41.5.5.9, 41.5.5.13, 43.3.7.4) need to be changed with "MaxRetries" concept.
Proposed text
1) Change the ECP transmit state machine (Figure 43-3, clause 43.3.4) with the proposed state machine (see the attached file ECP-transmit-state-machine.pdf)
In the proposed state machine, inc(retries) action is moved to newly added "Retry" state.
2) In Table 12-17 of clause 12.26.1, and table 12-18 of clause 12.26.1,
Change the variable "evbSysEcpDfltMaxTries" to "evbSysEcpDfltMaxRetries".
3) In Table 12-18 of clause 12.26.1,
Change the variable "ecpAdminMaxTries" to "ecpAdminMaxRetries".
4) In Table 12-26 of clause 12.17.1, clause 41.5.5.9, clause 41.5.5.13, and clause 43.3.7.4,
Change the variable "ecpOperMaxTries" to "ecpOperMaxRetries".
5) In Table 17-26 EVB MIB structure and object cross referece of clause 17.2.20,
Change "ieee8021BridgeEvbEcpOperMaxTries" to "ieee8021BridgeEvbEcpOperMaxRetries".
(Note: Ieee8021BridgeEvbEcpEntry of EVB MIB (17.7.20) is defined with "ieee8021BridgeEvbEcpOperMaxRetries")
Impact on existing networks
An early EVB implementation may have an incompatible MIBs and malfunctioning ECP transmit state machine. This clarification is needed to prevent further incompatible EVB implementations.
Originator
Name: | Kodirov Nodir and Sung Hyuk Byun | Email: | nodir@etri.re.kr<mailto:nodir@etri.re.kr>, shbyun@etri.re.kr<mailto:shbyun@etri.re.kr> |
Affiliation: | ETRI | ||
Submitted: | 2013-01-03 |