Need Help in understanding Wave vs Ethernet Hand off and Other Service Provider OTN level basics

[kanwarjit-singh]

Hi, 

I understand 10Gbe and I know how differently it can be delivered over different hand off viz commonly 10GBaseSR, LR, ER, ZR etc. This is how we deliver them on LAN side..but how are they related with LAN and WAN PHY hand off and when such hand offs comes into picture. 

Also  need help on how 10G Wave would be different from 10G Ethernet(WAN or LAN PHY). I understand that if we present a 10G wave to a customer then they can further demux it by plugiing them in their layer 1 box but 10G Ethernet cannot be broken down further...it has to go and connect to a L3 router or device. 

Please help me to get clear understanding and any links where I can read stuff from basic.... 

[Joseph W. Doherty]

SR, LR, ER, ZR don't change at all when used on the WAN side.  Of course, because of distance and cost issues, something like SR isn't generally used for any physical WAN connection, similarly, something like ZR isn't generally used with a LAN.

CWDM and DWDM, in principal, don't really differ that much from other foregoing fiber standards using SM fiber.  The just use a wavelength from a set of wavelengths that are close in frequency.  In theory, their additional precision would support a higher transmission bandwidth, but instead of using the bandwidth for a single higher effective rate, they support "standard" bandwidth rates and frequency multiplex.  (Also in principal, they work very much like a T1 that's frequency multiplexed to support multiple channels.)

The big advantage of frequency multiplexing, you can guarantee a set amount of bandwidth end-to-end.  The big disadvantage of frequency multiplexing, there's often "unused" bandwidth that something like time division multiplexing might take advantage of.

In other words, given one physical link, which is better, eight gig channels or one ten gig channel?  The answer is, it depends.  CWDM or DWDM provide you multiple channels, while the other fiber technologies provide one channel.

[kanwarjit-singh]

Hi Joseph, 

Thanks for your response but I couldnot understand most part of it..but I know you can help me... 

I am getting confused in understanding difference of how technology changed from SONET to DWDM and then to OTN. 

I m now writing down what I know about this.. 

SDH/SONET was traditional TDM based circuit which were originally laid for sending voice/PSTN signal but then IP traffic increased by time and people started sending data/IP over SONET/SDH. Normally data in LAN is Ethernet based, so in order to convert LAN data while sending it onto WAN network , we used GFP(generic framing procedure) so that  LAN payload can be mapped on to  SONET based WAN networks... 

NEXT is ...

SONET/SDH can be upgraded to support 40G on the same fiber but we get stability issues so in order to keep things stable SDH?SONET devices are kept fixed at 10Gbps.(STM64/OC192).  End point of those fiber were SONET boxes with layer 1 and layer 2(ethernet) ports. 

NEXT...

In order to increase the capability of same fiber....DWDM boxes were introduced and replaced by SONET boxes.... which can send multiple wavelength carrying different data over same fiber....

Managing DWDM boxes and monitoring became easy and capacity on same fiber was increased to 40G.

I dont know why DWDM was again replaced by OTN boxes at the end of fibers but I understand that OTN can further increase capacity of same fiber from 100G to 400G.....but HOW ? 

ALso....sometimes customers comes as ask for 10G Ethernet and ODU2e on a cable system...the BW are little bit different but do they terminate on different ports??? 

Are the devices placed across a cable system has different OTN interface(ODU2e) vs 10G interface. ?? 

PLus when I read about SONET/SDH, I always see that protection used in SNCP where we get one backup path with one primary path but when talk about DWDM and OTN then concept of ASON comes up which means that tertiary level of protection can be provisioned.....

is it because DWDM and OTN backbone uses T-MPLS based core network? Were SDH based core network not based on MPLS transport ? 

I am flooded with so much stuff with no clarity and whenever I try to find things on internet it is full of sales pitch rather than actual working.... 

I hope you will respond back or share some links where I can read .....

Please try to use simple English while responding... :)

[Joseph W. Doherty]

Yea, a lot of Internet information is sales oriented, and much assumes you well understand the subject.

What you've mentioned in you last post covers a great breadth of technologies, that both overlap and are independent.  Not something that can be easily addressed in a short reply.

I can now better appreciate why you're looking for link references.  Unfortunately I don't have any at hand.

Some of what you looking to understand might be found on Wiki.  Some might be found on sites like Cisco's main site as part of overview documentation.