10GのSFP+トランシーバーは色々と互換性に問題が生じる事が多いのですが、その一つにdual rateの実装方法のばらつきがあると思います。
| 10G single rate | 1/10G dual rate | |
|---|---|---|
| Transceiver codes | 0x10 0x00 0x00 0x00 0x40 0x00 0x0c 0x00 | 0x10 0x00 0x00 0x01 0x00 0x00 0x00 0x00 |
| Transceiver type |
10G Ethernet: 10G Base-SR
FC: short distance (S)
FC: Multimode, 62.5um (M6)
FC: Multimode, 50um (M5)
|
10G Ethernet: 10G Base-SR
Ethernet: 1000BASE-SX
|
| Rate identifier | 0x00 (unspecified) | 0x02 (8/4/2G Rx Rate_Select only) |
|
Option values
|
0x00 0x1a
|
0x00 0x3a
|
|
Option
|
RX_LOS implemented
TX_FAULT implemented
TX_DISABLE implemented
|
RX_LOS implemented
TX_FAULT implemented
TX_DISABLE implemented
RATE_SELECT implemented |
| BR margin, max | 10% | 0% |
| BR margin, min | 88% | 0% |
別なベンダーのDUAL RATEでは
Transceiver codes : 0x10 0x00 0x00 0x01 0x40 0x40 0x0c 0x55
Transceiver type : 10G Ethernet: 10G Base-SR
Transceiver type : Ethernet: 1000BASE-SX
Transceiver type : FC: short distance (S)
Transceiver type : FC: Shortwave laser w/o OFC (SN)
Transceiver type : FC: Multimode, 62.5um (M6)
Transceiver type : FC: Multimode, 50um (M5)
Transceiver type : FC: 800 MBytes/sec
Transceiver type : FC: 400 MBytes/sec
Transceiver type : FC: 200 MBytes/sec
Transceiver type : FC: 100 MBytes/sec
Rate identifier : 0x00 (unspecified)
Option : RX_LOS implemented
Option : TX_FAULT implemented
Option : TX_DISABLE implemented
BR margin, max : 0%
BR margin, min : 0%
Transceiver typeに10G Ethernet: 10G Base-SR, Ethernet: 1000BASE-SX両方がセットされ。OptionでRATE_SELECT implementedがセットされるのが正しいと思えるのですが、機器によってはそれでは不具合が生じる場合があるらしく、奇妙に思える値の組み合わせがセットされている光トランシーバーが販売されています。
信号線による切り替え
PIN 7 RS0
RS0 for Rate Select: Open or Low = Module supports 1.25 Gb/s High = Module supports 9.95 Gb/s to 10.3125 Gb/s 5
Transceiver data rate selected through the 2-wire bus in accordance with SFF-8472 Rev. 10.3. Soft RS0 is set at Bit3, Byte 110, Address A2h. Soft RS0 default state on power up is ‘0’ LOW, and the state is reset following a power cycle. Writing ‘1’ HIGH selects max. data rate operation. Transceiver data rate is the logic OR of the input state of the RS0 pin and soft RS0 bit. Thus, if either the RS0 pin OR the soft RS0 bit is HIGH then the selected data rate will be 9.95 and 10.3 Gb/s. Conversely, to select data rate 1.25 Gb/s both the RS0 pin and the soft RS0 bit are set LOW.