On 1/25/20 10:18 PM, Vinicius Costa Gomes wrote: > CAUTION: This Email originated from outside Televic. Do not click links or open attachments unless you recognize the sender and know the content is safe. > > > Hi, > > "Allan W. Nielsen" <allan.nielsen@xxxxxxxxxxxxx> writes: > >> Hi Vinicius, >> >> On 24.01.2020 13:05, Vinicius Costa Gomes wrote: >>> I have one idea and one question. >> Let me answer the question before dicussing the idea. >> >>> The question that I have is: what's the relation of IEC 62439-2 to IEEE >>> 802.1CB? >> HSR and 802.1CB (often called FRER - Frame Replication and Elimination >> for Reliability) shares a lot of functionallity. It is a while since I >> read the 802.1CB standard, and I have only skimmed the HSR standard, but >> as far as I understand 802.1CB is a super set of HSR. Also, I have not >> studdied the HSR implementation. >> Both HSR and 802.1CB replicate the frame and eliminate the additional >> copies. If just 1 of the replicated fraems arrives, then higher layer >> applications will not see any traffic lose. >> >> MRP is different, it is a ring protocol, much more like ERPS defined in >> G.8032 by ITU. Also, MRP only make sense in switches, it does not make >> sense in a host (like HSR does). >> >> [snip MPR explanation] >> >> Sorry for the long explanation, but it is important to understand this >> when discussion the design. > Not at all, thanks a lot. Now it's clear to me that MRP and 802.1CB are > really different beasts, with different use cases/limitations: > > - MRP: now that we have a ring, let's break the loop, and use the > redudancy provided by the ring to detect the problem and "repair" the > network if something bad happens; indeed. MRP is IEC 62439-2 > > - 802.1CB: now that we have a ring, let's send packets through > two different paths, and find a way to discard duplicated ones, so > even if something bad happens the packet will reach its destination; Not exactly, 802.1CB is independent of the network layout, according to the abstract on https://ieeexplore.ieee.org/document/8091139. The IEC 62439-3 standard mentions 2 network layouts: 2 parallel paths and a ring: - IEC 62439-3.4 Parallel Redundancy Protocol (PRP): this runs on 2 separated parallel paths in the network - IEC 62439-3.5 HSR (High availability seamless redundancy): this runs on a ring: each host sends all data in 2 directions, and when it receives its own data back, it discards it (to avoid a loop). (and it is better to implement IEEE, because the standard costs only 151$, and the IEC ones cost 2x410$) Kind regards, Jürgen
