# Media Redundancy Protocol > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Media_Redundancy_Protocol > Markdown URL: https://mediated.wiki/source/Media_Redundancy_Protocol.md > Source: https://en.wikipedia.org/wiki/Media_Redundancy_Protocol > Source revision: 1299453641 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Fault recovery system for Ethernet}} 250px|right|thumb|Figure 1: MRP ring in Ring-Closed status 250px|right|thumb|Figure 2: MRP ring in Ring-Open status '''Media Redundancy Protocol''' ('''MRP''') is a data [network protocol](/source/network_protocol) standardized by the [International Electrotechnical Commission](/source/International_Electrotechnical_Commission) as IEC 62439-2. It allows rings of [Ethernet](/source/Ethernet) switches to overcome any single failure with recovery time much faster than achievable with [Spanning Tree Protocol](/source/Spanning_Tree_Protocol).{{Cite journal |title= Performance Analysis of Media Redundancy Protocol (MRP) |volume= 9|author= A. Giorgetti|journal= IEEE Transactions on Industrial Informatics |date= February 3, 2013 |pages= 218–227 |doi= 10.1109/TII.2012.2186584 |publisher= IEEE Computer Society |s2cid= 5696119|display-authors=etal}} It is suitable to most [industrial Ethernet](/source/industrial_Ethernet) applications. == Properties == MRP operates at the data link layer (OSI Layer 2) of Ethernet switches and is a direct evolution of the HiPER-Ring protocol developed by Hirschmann in 1998.{{Cite web |title= Hirschmann Networking Interoperability to Industrial/Process and EtherNet/IP Environments |work= White paper |date= December 8, 2003 |url= http://www.industrialnetworking.com/pdf/Ethernet_IP.pdf |accessdate= August 17, 2013 |url-status= dead |archiveurl= https://web.archive.org/web/20080516213222/http://www.industrialnetworking.com/pdf/Ethernet_IP.pdf |archivedate= May 16, 2008 }}{{Cite web |title= Industrial Redundant Network |author= Marc Lee |work= Singapore BICSI conference |date= November 5, 2010 |url= http://www.bicsi.org/uploadedfiles/PDFs/Conferences/singapore2010/day1/1.7%20Industrial%20Redundant%20Networks%20-%20Marc%20Lee,%20Belden%20Automation.pdf |accessdate= August 17, 2013 }} Hirschmann is now owned by [Belden](/source/Belden_(electronics_company)).{{Cite web |title= HiOS - Hirschmann™ Operating System |work= Web site |publisher= Hirschmann a Belden Brand |url= http://www.hirschmann.com/en/Hirschmann_Produkte/Industrial_Ethernet/Software/HiOS-Hirschmann-Operating-System/index.phtml |accessdate= August 17, 2013 |url-status= dead |archiveurl= https://web.archive.org/web/20130512013939/http://hirschmann.com/en/Hirschmann_Produkte/Industrial_Ethernet/Software/HiOS-Hirschmann-Operating-System/index.phtml |archivedate= May 12, 2013 }} MRP is supported by several commercial [industrial Ethernet](/source/industrial_Ethernet) switches.{{Cite web |title= Fast Ethernet DIN Rail switch 8-9 ports |work= Product page |publisher= Belden |url= http://www.e-catalog.beldensolutions.com/link/57078-24455-49846-49996-176335-168500/en/RSR20-0800T1T1T1SCCHPHH07.0./0 |accessdate= August 17, 2013 }}{{Cite web |title= PROFINET Open Industrial Ethernet standard for automation |publisher= Omron |date= October 12, 2009 |url= http://www.factorycontrols.com.au/pdf/datasheet/automation_systems/CJ1-PNT21%20Profinet%20Brochure.pdf |url-status=dead |archiveurl= https://web.archive.org/web/20110216161154/http://factorycontrols.com.au/pdf/datasheet/automation_systems/CJ1-PNT21%20Profinet%20Brochure.pdf |archivedate= February 16, 2011 |accessdate= August 17, 2013 }} In an MRP ring, the ring manager is named Media Redundancy Manager (MRM), while ring clients are named Media Redundancy Clients (MRCs). MRM and MRC ring ports support three statuses: disabled, blocked, and forwarding: * Disabled ring ports drop all the received frames. They also do not send any frames. * Blocked ring ports drop all the received frames except the MRP control frames. They also do not send any frames except MRP control frames. * Forwarding ring ports receive all frames and also forward the received frames. During normal operation, the network works in the Ring-Closed status (Figure 1). In this status, one of the MRM ring ports is blocked, while the other is forwarding. Conversely, both ring ports of all MRCs are forwarding. Loops are avoided because the physical ring topology is reduced to a logical line topology. In case of failure, the network works in the Ring-Open status (Figure 2). For instance, in case of failure of a link connecting two MRCs, the MRM sets both of its ring ports to the forwarding state; the MRCs adjacent to the failure each have a disabled port (because of the link loss) and a forwarding ring port; the other MRCs have both ring ports forwarding. Also, in the Ring-Open status, the network logical topology is a line. == Frame structure == MRP information is sent in the form of an [Ethernet frame](/source/Ethernet_frame), with the [EtherType](/source/EtherType) field set to 0x88E3. The frames are built by [Type–length–value](/source/Type%E2%80%93length%E2%80%93value) (TLV) structures, allowing organizationally specific information. == Standards == The [International Electrotechnical Commission](/source/International_Electrotechnical_Commission) standard for MRP was published in 2010 as IEC 62439-2{{cite web |title=IEC 62439-2:2021. Industrial communication networks - High availability automation networks - Part 2: Media Redundancy Protocol (MRP) |url=https://webstore.iec.ch/en/publication/62849 |website=International Electrotechnical Commission |publisher=IEC Webstore |access-date=8 July 2025}} and amended in 2012. The standard IEC 62439 published in 2012 also defined the following protocols: * [Parallel Redundancy Protocol](/source/Parallel_Redundancy_Protocol) (PRP) * Cross-network Redundancy Protocol - CRP * Beacon Redundancy Protocol - BRP * [High-availability Seamless Redundancy](/source/High-availability_Seamless_Redundancy) (HSR) With the settings specified in IEC 62439-2, MRP guarantees a worst-case recovery time of 500 ms, 200 ms, or 30 ms in rings composed of up to 50 switches, and a worst-case recovery time of 10 ms in rings composed of up to 14 switches. ==See also== * [Fieldbus](/source/Fieldbus) ==References== {{Reflist}} {{Ethernet}} Category:Networking standards Category:Network protocols Category:Industrial Ethernet --- Adapted from the Wikipedia article [Media Redundancy Protocol](https://en.wikipedia.org/wiki/Media_Redundancy_Protocol) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Media_Redundancy_Protocol?action=history)). 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