DS3 Breakdown for bandwidth command

Greetings,
An friend and I are trying to determine how Cisco arrives at 44736 for
a DS3. Furthermore we want to create a table for other speeds within a
DS3's capacity.

There is a minor disagreement on how to calculate the bandwidth. I vote
1544 * # of channels. He votes for "10" x 1024 for a 10 meg circuit.

However, I get the feeling we are both not right. Cisco shows examples
of
bandwith 44736

for a full ds3. However, I don't know how they come up with that...

1544 x 28 = 43232
1544 x 29 = 44776 (CLOSE, but no cigar)

1024 x anything = not close

My understanding is it should be 1544 x 28. I'm told that the extra
1504 for the 44736 is due to framing. I can not find any good
information for the framing overhead that equals 1504. I've found some
that'll equal 1536. (64 x 24) We use C-bit framing....

Any input on exactly how to calculate these channels and so forth will
be appreciated.

ceyko1@gmail.com

writes:
>An friend and I are trying to determine how Cisco arrives at 44736 for
>a DS3. Furthermore we want to create a table for other speeds within a
>DS3's capacity.

You'll really want to readup on how the information is mashed and
splitup inside a DS3. There's several tech articles for the googling..

>There is a minor disagreement on how to calculate the bandwidth. I vote
>1544 * # of channels. He votes for "10" x 1024 for a 10 meg circuit.

You're missing all the framing and sub-code information bits stuffed
into the mix. 1544*28 is closer, but missing the framing and c-bits.

4 DS1s form a DS2.
7 DS2s form a DS3.

A DS2 M-Subframe takes 12-bits from each of its 4 DS1s, and starts
with a frame bit, and seperates each of the 48-bit info blocks with
c-bits or frame bits.

A DS2 Multiframe takes its component DS2 M-Subframes and seperates
them out with M framing bits, and then you get M23 Stuff blocks from
interleaving each of your DS2s.

Finally, you get a DS3 M-Subframe from each of the DS2 M-Subframes,
and you stuff those together into the full DS3 Frame with additional
framing and c-bits.

Now-a-days, they don't need the clock recovery bits, so the c-bit
framing uses them for sub-band signal codes downstream.

Whew.

Doug,
Thank you for the response. It is appreciated.

Take care,
ceyko