Arista fixed configuration Jericho2 deep buffer switches

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7280CR3-32P4 and 7280CR3K-32P4

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7280CR3-32D4 and 7280CR3K-32D4

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7280PR3-24 and 7280PR3K-24

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7280DR3-24 and 7280DR3K-24

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7280CR3-96 and 7280CR3K-96

Announcement webinar 23 May 2019, first ship Q3 2019

Cisco does not make fixed configuration switches with Jericho2 ASICs; they use the ASICs in high-end line cards for chassis solutions. Arista makes chassis cards too, but not reviewed here. Arista makes switches with QSFP-DD and OSFP optics plugins. Jericho2 switches can contain external TCAM, or not. External TCAM is indicated by a K in the model number. Overall, there are ten models.

OSFP means OctalSFP, so 8 lanes, 50 Gb/s PAM4 yields 400 Gb/s.

QSFP-DD means 2X quad, so 8 lanes, 50 Gb/s PAM4. Yields 400 Gb/s. QSFP-DD has its plug connector on the back end arranged so that a QSFP module can slide into the slot and be recognized as a single density QSFP. This provides backward compatibilty and what they call investment protection.

OSFP modules are larger which lets them disipate more heat and thus do stuff beyond the thermal limits of QSFP-DD. An example announced on March 9, 2020 is the coherant 400G-ZR transceiver paired with an EDFA optical amplifier.

picture of a transciever and line amplifer in OSFP packages

This transceiver and amplifier pair are expected to start shipping in the second half of 2020.

Packet Buffers

Each Jericho2 ASIC is co-packaged with an 8 GB hbm memory. This memory is used to store packets when the on-chip 16 MB memory starts to fill. The question dynamic vs static buffers is answered for Broadcom in an Arista architecture white paper. Buffer allocation is dynamic. Quoting:
. . . the majority of the buffer is allocated in a dynamic manner wherever it is required across potentially millions of VoQs per system:
  • ~30% buffer reserved for traffic per Traffic Class per Output Port
  • ~15% buffer for multi-destination traffic
  • ~55% available as a dynamic buffer pool

    Output Port CharacteristicMax Packet Buffer DepthMax Packet Buffer Depth (msec)
    10 Gb/s output port50 MByte40 msec
    25 Gb/s output port125 MByte40 msec
    40 Gb/s output port200 MByte40 msec
    50 Gb/s output port250 MByte40 msec
    100 Gb/s output port500 MByte40 msec
    400 Gb/s output port500 MByte10 msec