I have few basic questions on Ethernet..
What's the difference between Optical Ethernet and Electrical
Ethernet?
Given that the optical Ethernet is also transmitted over a DWDM
wavelength , why do we need OTN to transmit Optical Ethernet over
longer distances ( I see optical Ethernet is limited to 80km only
..why ? what is limiting the distance?)
Hello Venkat,
You wrote:
I have few basic questions on Ethernet..
OK.
What's the difference between Optical Ethernet and Electrical
Ethernet?
The difference is only the line signal. The characteristics of
electrical signals and optical signals are different.
Electrical are normally short distance, e.g between equipment
in the same building.
Optical are normally longer distance, outside the building.
Given that the optical Ethernet is also transmitted over a DWDM
wavelength , why do we need OTN to transmit Optical Ethernet over
longer distances ( I see optical Ethernet is limited to 80km only
..why ? what is limiting the distance?)
It depends on the optical components that are used.
The IEEE standard for the Ethernet optical interface limits it
to about 80km.
Best regards, Huub.Stephen Hope stephen_hope@xyzworld.com
Some optics suppliers will provide parts with a longer reach.
I assume transport Ethernet is sending Ethernet signals on DWDM
wavelengths directly) ?
I assume transport Ethernet is sending Ethernet signals on DWDM
wavelengths directly) ?
No, in 802.3 Ethernet architectures, that is MAC 802.3 over RS/PHY 802.3, you don't have PHY 802.3 signals that are DWDM.
Best regards,
MIchelot
PHY 802.3 can be an optical signal.
It is up to the Line module to decide on what wavelength to transmit
the signal.
*Finisar 10GBASE-ZR/ZW Ethernet XFP
*Up-to 80 km over SMF @ 10Gbps
*XFP MSA & IEEE 802.3ae
You are neither sured that 2 of these interfaces from different vendors can operate together. Some vendors use 10GBASE-ZR/ZW on STM-64, others in OTU2 and OTUe (which OTU2e is not compliant to G.709 OTN.
Hi,
Thanks for the replies.
I still don't understand why do we need transport technologies like OTN and SONET , when we have transport Ethernet ( I assume transport Ethernet is sending Ethernet signals on DWDM wavelengths directly) ?
Why cant transport Ethernet travel same distance as OTN ? Hub you said , "It depends on the optical components that are used" . Does that mean optical components used in Transport Ethernet are cheaper than components used for OTN ?
Thanks
Krishna
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