Re: Does only decimal system work for data rate specification?
For informational purposes only :-)....
802.3ad specifies a mechanism for aggregating multiple similar speed
ethernet links into a single "aggregate port". Customers use this today to
provide performance scaling when they don't want to upgrade to the next
higher speed ethernet. In some cases, customers use a single bundle of
copper to transport both physical ports, and it seems that some clever
implementer or could design a way for customers to use WDM to transport the
parallel paths over a single fiber.
At 09:09 AM 12/9/99 -0700, Mike Wincn wrote:
>At 09:55 AM 09-12-99 +0100, Fenghao Mu wrote:
>>1) Why we prefer to only specify 10GE rather than suggest other
>>reasonable data rates related to gigabit Ethernet, say 2.5/5 gigabit
>suppose i turn the question around -- what would be the point of having many
>more datarate communication standards, when we already have 1, 10, 100, and
>1000-base-whatever? it isn't clear to me that finer granularity offers any
>>2) Why we need Hari coding to tie four individual links together instead
>>of sending data separately?
>Hari doesn't code anything. Hari is a proposed method of standardizing
>PMD interconnect that uses existing line codes. otherwise, the four serial
>links are separate, other than for issues related to word- or byte-striping.
>>3) Does our data rate specification fit with market requirement and
>>technology progress well?
>yes, else there would not be much interest in developing a new standard
>for interoperable, higher-datarate systems. you should understand that
>no one will be compelled to use any standards-based 10GbE system,
>other than for desire to participate in that market space. that has been
>true for all 802.3 stuff, since inception.
>>1. From a customer point of view, only 1GE and 10GE give less choices
>>for one to build a good switching structure. He has to chose between two
>>possible data rates, either 1GE or 10GE. It might be very difficult for him
>>to upgrade his data links, in other words, 10GE is too luxurious and 1GE
>>is insufficient for his requirement. What is his best solution?
>there is already interest in developing a higher datarate standard. issues
>such as feasibility, interoperability, and so on are to be resolved in the
>standards development process. there will always be technological
>and dollar cost barriers to general market entry, and though the standards
>process helps to reduce that cost it cannot be removed entirely.
>>2. Data rate evenly distributed networks are seldom met in reality, and it
>>exists only in people's imagination. Designing a switcher fabric based on
>>this imagination will cause a big waste of resource.
>i think you will need to define your use of "wasted resource" more carefully
>before anyone can address this. do you want 100% capacity, 24 x 7? you
>won't find it here. define your conditions and we can proceed.
>>[...] If we could use 2.5/5/10 GE data
>>rates, we can individually assign a data rate for a path in a network
>>according different requirements. Multiple data rates can be very helpful
>>for optimal I/O pad usage.
>you can do that now, at 1, 10, 100, or 1000MBaud. (aside: i offer this for
>the sake of completion. does anyone know whether Starlan is still in use?)
>>3. There is no reason why we only specify 10GE, which bonds 4 individual
>>links together. Probably there isn't any information source or sink today
>>which has to be specified at 10Gb/s.
>if that were true, there would not be much interest in HSSG participation.
>>5. At today's technology, few devices could support 10GE within one link
>>for a meaningful distance.
>have you ever heard of OC-192/SDH-48? you may want to try a search
>> From technology point of view, there isn't any
>>remarkable breakthrough so that we can utilize a new and cheap device
>>to implement 10GE links.
>fast VCSELs, DMD-flattened M-M fiber, fast (linear) equalization, FEC, MAS
>and the like all offer potentially cheap solutions for 10GbE. you may want
>to have a look at presentation notes at the reflector site.
>>6. In fact, we could simply extend the Gigabit Ethernet standard to
>>2.5/5 GE specification by adapting new speed as a smooth move. If we
>>use 8B10B encoding, the speed will be 3.125/6.25 Gb/s, respectively.
>>Simple and efficient! Why not?
>i gather that people considered that, early on. seems there wasn't much