Equal-cost multi-path routing

<h2 id="history">History</h2>
<p>Load balancing by per-packet <a href="/facts/Multipath_routing/kmyJXlW8">multipath routing</a> was generally disfavored due to the impact of rapidly changing latency, <a href="/facts/Packet_reordering/ImewjL5P">packet reordering</a> and <a href="/facts/Maximum_transmission_unit/l2FdKoLa">maximum transmission unit</a> (MTU) differences within a network flow, which could disrupt the operation of many Internet protocols, most notably <a href="/facts/Transmission_Control_Protocol/WW4sPrt9">TCP</a> and <a href="/facts/Path_MTU_discovery/0SyST1ms">path MTU discovery</a>. RFC 2992 analyzed one particular multipath routing strategy involving the assignment of <a href="/facts/Traffic_flow_(computer_networking)/Yp8UP6ys">flows</a> through <a href="/facts/Hash_algorithm/rk6MlCt3">hashing</a> flow-related data in the <a href="/facts/Packet_header/DSbn3tM1">packet header</a>. This solution is designed to avoid these problems by sending all packets from any particular network flow through the same path while balancing multiple flows over multiple paths in general.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
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<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Link_aggregation/3BE3qHDT">Link aggregation</a></li>
<li><a href="/facts/Shortest_Path_Bridging/xslEBCKB">Shortest Path Bridging</a> – establishes multiple forward and reverse paths on <a href="/facts/Ethernet/nMfhU8tU">Ethernet</a> networks.</li>
<li><a href="/facts/Source_routing/1Xtpqwby">Source routing</a></li>
<li><a href="/facts/TRILL/7lHM52Xe">TRILL</a> – enables per flow pair-wise load splitting without configuration and user intervention.</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://etutorials.org/Networking/Integrated+cisco+and+unix+network+architectures/Chapter+8.+Static+Routing+Concepts/Equal-Cost+Multi-Path+ECMP+Routing/">Etutorials: Equal-Cost Multi-Path (ECMP) Routing</a></li>
<li><a href="http://paris-traceroute.net">Paris-Traceroute: traceroute for ECMP networks</a></li>
<li><a href="https://dublin-traceroute.net">Dublin-Traceroute: NAT-aware traceroute for ECMP networks</a></li>
<li><a href="https://dl.acm.org/doi/10.1109/TNET.2016.2614247">Traffic Engineering With Equal-Cost-MultiPath: An Algorithmic Perspective</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Multipath Issues in Unicast and Multicast Next-Hop Selection. doi:10.17487/RFC2991. RFC 2991. Retrieved 16 December 2013. <a href="https://tools.ietf.org/html/rfc2991" target="_blank">https://tools.ietf.org/html/rfc2991</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Analysis of an Equal-Cost Multi-Path Algorithm. doi:10.17487/RFC2992. RFC 2992. <a href="https://datatracker.ietf.org/doc/html/rfc2992" target="_blank">https://datatracker.ietf.org/doc/html/rfc2992</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
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Equal-cost multi-path routing open-in-new

Equal-cost multi-path routing