Multipath selection in an ethernet fabric in a modular network element

A modular network element configured for Ethernet path selection, the modular network element comprising:

• one or more ingress line modules;
• one or more switch modules in a chassis;
• and
• one or more egress line modules, wherein the one or more ingress line modules and the one or more egress line modules are located separate from the chassis and connected to the chassis via cabling,
• wherein one or more Ethernet flows are distributed from the one or more ingress line modules to the one or more egress line modules via the plurality of switch modules,
• wherein the one or more ingress line modules receive fabric state information from the chassis out-of-band via the cabling,
• wherein, responsive to congestion on a path through the plurality of switch modules, a new path is selected by an ingress line module for an Ethernet flow, and
• wherein timing is distributed from the chassis out-of-band via the cabling, wherein the timing is determined at the chassis using a Time Division Multiplexing (TDM) flow which is spread over the plurality of switch modules, and wherein the chassis utilizes a TDM packet header to estimate relative path latency differences.

A modular network element configured for Ethernet path selection, the modular network element comprising:

• one or more ingress line modules;
• one or more switch modules in a chassis;
• and
• one or more egress line modules, wherein the one or more ingress line modules and the one or more egress line modules are located separate from the chassis and connected to the chassis via cabling,
• wherein one or more Ethernet flows are distributed from the one or more ingress line modules to the one or more egress line modules via the plurality of switch modules,
• wherein the one or more ingress line modules receive fabric state information from the chassis out-of-band via the cabling,
• wherein, responsive to congestion on a path through the plurality of switch modules, a new path is selected by an ingress line module for an Ethernet flow, and
• wherein the Ethernet flow comprises an elephant flow and each flowburst of the elephant flow is eligible to take a different path if its interburst gap is larger than a difference in latency between a current path and the new path.