Which of the following options are available for ODUk SNCP switching conditions? (Multiple choice)

If a weak signal light and a strong pump light are transmitted simultaneously in an optical fiber, and the wavelength of the weak signal light is within the Raman gain bandwidth of the pump light, the energy of the strong pump light is combined into the oscillation mode of the silicon material of the optical fiber through stimulated Raman scattering (SRS), and then emitted at a longer wavelength, which is the wavelength of the signal light, thereby amplifying the weak signal light and obtaining Raman gain.

For ODUk SNCP protection, if the pass-through site is an electrical relay site, it is recommended to configure the SNCP type as SNC/I when configuring the protection.

Which of the following are communication quality alerts? (Multiple choice)

Which of the following is the meaning of SFD in the Ethernet frame structure?