8/16G Fiber Channel 與 10G Ethernet transceiver

同事問 Fiber Channel Ttransceiver (8/16G)  與 Ethernet (10G) 這幾種收發器 (Transceiver)是否可已有向下相容的機制,8G 與 16G Fiber Channel transceiver 是確定向下相容的,在 Finisar , Avago 或是在 Brocade 官網裡面定義了Fiber Channel Transceiver 的相容機制.

• Finisar:FTLF8529P3BxV
  4 Gb/s Fibre Channel Compliant
  8 Gb/s Fibre Channel Compliant
  16 Gb/s Fibre Channel Compliant (Data Rate max 14.025 Gb/s)
• Avago:AFBR-57F5PZ
  14.025/8.5/4.25 GBd
• Brocade:
  Performance Fibre Channel: 4.25, 8.5, and 14.025 Gbps line speed, full duplex; autosensing of 4, 8, and 14 Gbps port speeds
  Up to 14.025 Gb/s bi-directional data links

note:
但明明規格是 16Gb 為什麼只支援到 14.025Gb 呢!!的確他的速限是 14.025 採用了 64/66 編碼方式.所以在實際計算時

• 1G Speed – 1062.5Mb x 8/10 (八個位元的資料串上用十位元來加以編碼) x 1/8 (8bits = 1byte) x 2012/2048 (資料有效位元) = 104.38MB

• 16G Speed – 14.025Gb x 64/66 (64個位元的資料串上用66位元來加以編碼) x 1/8 (8bits = 1byte) x 2012/2048 (資料有效位元) = 1.67GBM   所以此規格才可以號稱為 16G Fiber Channel

至於 10G Ethernet 是否可以跟 8/16G 相容,答案應該是不行,目前我並沒有看到規格書上有說明此2種 transceiver 可以共用.

答案是有的 Avago – AFBR-57F5xMZ http://www.avagotech.com/pages/en/fiber_optics/storage/16g_fibre_channel/afbr-57f5xmz/
These CDRs will lock at 14.025Gb/s (16GFC) but must be bypassed for operation at 10.3125 Gb/s (10GE), 8.5Gb/s (8GFC) and 4.25 Gb/s (4GFC)

Finisar 也有類似的 Module.