IEEE Std 802.1Qch pdf free download

IEEE Std 802.1Qch pdf free download.Local and metropolitan area networks- Bridges and Bridged Networks- Amendment 29: Cyclic Queuing and Forwarding.
where interval I— I becomes interval I. A relay (such as Bob) can of course choose when to start reception assignment to I in relation to I; it is assumed that Boh intent is that the earliest frame to be assigned to I is the first whose very last octet (or other frame transmission encoding symbol) is still on the transmission medium (or other definable external event to what is considered to be Bob reference point) at 1, thus placing any accommodation of known implementation dependent delays within Bob under Bohc control.
While Bob attempts to start I reception with a frame coming ofT the medium at i, and may factor known and repeatable internal delays into the way he goes about that intent, his actual start time depends on:
a) The error in Bob .c time sync (i.e., the error in his determination as to when I actually occurs).
b) The maximum deviation (jitter) in Bohc use of that time.
c) Additional delays that Bob does not account for, such as delays in selecting the output queue to be used for i.
Alice has to stop transmitting frames for i—I before I, by a time that is the sum of Bob c possible early start of i as a consequence of a) through c), and the following:
d) The error in Alice time sync (i.e., the error in her determination as to when t occurs).
e) The maximum deviation (jitter) in Alice use of that time.
f) The time between Alice deciding to commit a frame for transmission and the appearance of the last octet/symbol “on the medium” at Alice .c end.
g) The length of ‘ihe medium” in transmission time, i.e., the time for the last octet/symbol to leave Alice and reach Bob, including any consideration of’ the effect of interfering frames or fragments.
The description of CQF in terms of a number of consecutive intervals (as opposed to their support by “odd! even” queues, as discussed in T.2 onwards) gives easy answers to what to do with traffic still queued when its selected transmission interval has expired—discard it, or mark it down (discard eligible or priority change) and generate an alarm. In an environment where the stream bandwidth is allocated appropriately (i.e.. the bandwidth allocated per time interval is less than can be receivedJtransmitted in the chosen interval duration), this will be a rare occurrence, the traffic that follows will be conformant, and the overall system performance will be recoverable.
The discussion so far has assumed that all link speeds are the same; however, the situation becomes more complicated when links of different speeds are considered. One typical arrangement might comprise low speed links at the start and end of the path (network periphery to periphery), another with the high speed towards one end (periphery to core or vice versa). Taking the first of these, and placing Alice at the first transition from slow to fast, Bob as her fast neighbor, Charlie as his fast neighbor, and Donald at the transition from fast to slow, the important thing (treating the fast core of the network as a CQF black box) is that all conformant traffic received by Alice in interval i (say) is transmitted by Donald in a later interval i+n. A number of internal arrangements might he made between Alice, Bob, Charlie, and Donald to make this happen and would be valid from an external CQF perspective. It is also possible to consider fractional ii, where n is still> 1, as Alice may need to collect the entirety of any slow cycle before transmitting that in a more compressed burst into the rest of the fast network. More complex possibilities are equivalent to redefining the slow cycle time. Some of the less elaborate possibilities for the use of links of different speeds are discussed in T.5.
IEEE Std 802.1Qch pdf download.