Hi OCP Networking group, Please find the spec and design package for the Facebook submission Backpack- 128x100G at the OCP site below: http://www.opencompute.org/wiki/Networking/SpecsAndDesigns#Facebook_Backpack_-_128x100G
The spec version is v.92 Design package v0.1 The design files submitted here reflect the design that’s currently in production at Facebook datacenters. Also below are answers to a couple of questions that were raised during the OCP community review: - How is OpenBMC different for a chassis based switch vs the previous release for Wedge100 o There is the concept of a Master BMC in Backpack that acts as the central point of monitoring/reporting for power/temperature/fans for the entire chassis. o This is implemented on the CMM management module in Backpack. o The CMM implementation also uses a new BMC SOC, and anew kernel/utilities. o There are slave BMCs that exist on every line card as well as fabric cards. These are similar to the openBMC that exists on the Wedge100 switch. - How does the Backpack switch get provisioned/boot up? o Wedge100 is a single unit to provision, while for Backpack we have 25 units that provision independently o (12 SCMs + 12 LC/FC + 1 CMM). For speeding up initial provisioning all these cards go roughly in parallel (see ii) o ii) For each pair of LC/FC, SCM – LC/FC provisions first and then triggers a SCM provisioning job. In wedge100, this o is self contained in a single provisioning job. o iii) Flip side of provisioning is unprovisioning. This happens roughly independently for all 25 cards in Backpack. Exception here is o we unprovision SCM first followed by its paired LC/FC. We will likely break this serialization in future. o iv) Same infrastructure is used for provisioning Backpack as for wedge100. A simple way of seeing Backpack provisioning o is to see each card as a system to be provisioned unto itself. o v) Since the chassis is not ready to take traffic until all cards are provisioned, each card in FSW comes up as drained – I.e. o it does not announce out any traffic bearing prefix. Only once all cards have been provisioned and chassis has been audited o do we undrain it. We follow the same process for vendor FSWs even though there its a single SUP to provision Please let us know if you have any questions about the package or if you are interested in integrating with Backpack from a software perspective or potentially obtaining a Backpack when they are generally available. We plan to bring Backpack for OCP Incubation committee review soon. Ramesh Padmanabhan Luis MartinGarcia Technical Program Manager, Facebook Network Partner Engineering, Facebook
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