ITU G. 8032 Standard Ethernet Ring Protection
Evidently, Industrial Ethernet has been migrating as the main stream technology comparing the serial communications with the advantage of high speed, low cost, long range, PHY independence and easy deployment, the market is shifting toward Ethernet technology which is a proved and matured one where Industrial communication is required.
The most renowned redundancy protocol “RSTP” or “MSTP” in Ethernet enjoys the freedom of topology that connects several switches in a ring forming a “closed loop” where the RSTP or MSTP will calculate the closest backup bath to reconnect the path if broken which is commonly called “Ethernet Ring Switching”. But the protection scheme from generating broadcast storm is essential to negotiate which link is the most appropriate one to avoid the loop amongst all switches where is like a tree branching out so the calculating and responding will be greater along with the growth of network which could be subject from 2~120 seconds even 5 minutes. This irrevocable recovery time is intolerant in some critical network infrastructure like sub-station, aviation, traffic light control etc where the even 1 second lost connection is fatal, so the proprietary ring is commonly seen in the market for each brand to improve the ring recovery time to the range of 10~50ms.
However, lacking of inter-operability from brand to brand results in less-resiliency of infrastructure and higher TOC, also the test measurement is unlikely the same to tell which product is actually better. The same phenomena is happening in the Telcom industry where many ISPs are adapting carrier Ethernet to replace expensive SDH/Sonet/ATM, so big Ethernet system players are launching their proprietary recovery protocol like CISCO PRP(Resilient Packet Ring), Extreme Network EAPS(Ethernet Automatic Protection Switching) to have the same failure recovery that of SDH/Sonet ring. The controversial interoperability is bothering the ISP with the most evidential example of CISCO PRP that has different MAC header than Ethernet standard.
Besides, all those ring telco switches are having the following issues in the real site deployment:
1. Command setting is minute and complicated
Each ring switch must complete the parameters correctly so that the redundancy will operate normally, if any switch is missing out, the backup will fail.
2. Status quo is missing
There are many elements to form a ring redundancy, but the current available products only can inform of ring fail without warning where has gone wrong.
3. Multicast exclusion
When the fail over is occurring, the current redundancy recovery is only valid within data packets while leaving out the multicast packets causing the blockage of video stream until it rebuilds the IGMP table. This is the discrepancy of current ring.
To solve interoperability issue, ITU(International Telecommunication Unit) has draft a protocol, G.8032, Ethernet Ring Protection Switching(ERPS), to be compatible with Ethernet standard and enhanced the recovery scheme and protocol to be less than 50ms. The G.8032 v2 draft (almost final) is complete enough for many big Ethernet system players that are rushing out their equipment to be conforming with, which will be deem as main stream technology soon. The benefits of G.8032 are:
1. <50ms recovery time when failover
2. G.8032 is the standard protocol which can interact amongst different brands without being tie up by the same supplier to ensure the best investment
3. G.8032 has defined the protocol scheme, parameters, functions, test measures to be unified that the users can evaluate the possible network infrastructure without literally testing each brand in large scale.
Lantech is implementing ITU G.8032 in our new series of switches and also offers the two key advantages for the real applications
1. Zero Configuration Enabled automatic setting for the best parameters without manual operation to avoid miss-counting mistakes for G.8032
2. Multicast Integration Unlike the current ring which is only refreshing Mac address table instead of IGMP one when failover, Lantech G.8032 ring will also recover the video stream link in less than 20ms when the video client is disconnected without waiting for the query to － the path in 60~180 seconds.