Discussion:
Cross Connection
(too old to reply)
John Reinhold
2007-09-15 01:30:01 UTC
Permalink
Dear all,

I am new to the SDH equipment and seeking for some advices for the
following basic questions:

1. There are a lot descriptions about SDH product that stating
a. 16 X 16 VC4
b. 8 X 8 VC4 non blocking cross connection
c. cross connect VC4/VC3/VC12 which equivalent to 64X 64 VC4.
What are those really mean and how can one accurately calculate how
much matrix capacity he or she will need?

2. There are two protection method that keep me confused: 1+1 and
1:N. What are the differences between two?

Please kindly help out!

Thanks a lot.

Raymond
--
Via: http://www.jumlers.com/comp.dcom.sdh-sonet/
Azhar
2007-09-15 08:02:53 UTC
Permalink
Post by John Reinhold
Dear all,
I am new to the SDH equipment and seeking for some advices for the
1. There are a lot descriptions about SDH product that stating
a. 16 X 16 VC4
b. 8 X 8 VC4 non blocking cross connection
c. cross connect VC4/VC3/VC12 which equivalent to 64X 64 VC4.
What are those really mean and how can one accurately calculate how
much matrix capacity he or she will need?
2. There are two protection method that keep me confused: 1+1 and
1:N. What are the differences between two?
Please kindly help out!
Thanks a lot.
Raymond
--
Via:http://www.jumlers.com/comp.dcom.sdh-sonet/
Cross connection capacity depends on swtiching matrix IC used in cross
switch card. It is always in the format INPUT x OUTPUT. where input
and output are always equal. It denotes the number of cross
connections you can create in the node.

Every tributary and line card uses service buses on the backplane to
connect to cross switch card. 16x16 VC4 means 16 STM-1 buses between
cross switch card and service cards.
Azhar
2007-09-15 08:06:32 UTC
Permalink
Post by John Reinhold
Dear all,
I am new to the SDH equipment and seeking for some advices for the
1. There are a lot descriptions about SDH product that stating
a. 16 X 16 VC4
b. 8 X 8 VC4 non blocking cross connection
c. cross connect VC4/VC3/VC12 which equivalent to 64X 64 VC4.
What are those really mean and how can one accurately calculate how
much matrix capacity he or she will need?
2. There are two protection method that keep me confused: 1+1 and
1:N. What are the differences between two?
Please kindly help out!
Thanks a lot.
Raymond
--
Via:http://www.jumlers.com/comp.dcom.sdh-sonet/
Cross connection capacity depends on swtiching matrix IC used in cross
switch card. It is always in the format INPUT x OUTPUT. where input
and output are always equal. It denotes the number of cross
connections you can create in the node.

Every tributary and line card uses service buses on the backplane to
connect to cross switch card. 16x16 VC4 means 16 STM-1 buses between
cross switch card and service cards.
Huub van Helvoort
2007-09-15 10:54:26 UTC
Permalink
Hello Raymond (or is it John ;-),
Post by John Reinhold
I am new to the SDH equipment and seeking for some advices for the
1. There are a lot descriptions about SDH product that stating
a. 16 X 16 VC4 b. 8 X 8 VC4 non blocking cross connection
In general it desribes the number of inputs X the number of outputs.
Post by John Reinhold
c. cross connect VC4/VC3/VC12 which equivalent to 64X 64 VC4. What are
those really mean and how can one accurately calculate how
much matrix capacity he or she will need?
The capacity is the sum of I/O at the line interfaces, e.g. an STM-16
requires 16 I/O, the number of tributaries, e.g. how many VC-4 can
be added/dropped in an ADM.
Post by John Reinhold
2. There are two protection method that keep me confused: 1+1 and
1:N. What are the differences between two?
In general 1+1 means that at the source the signal is always
sent on the working path AND on the protecting path.
In 1:1 the original signal is sent either to the working
path OR to the protecting path, when the original signal
is not using the protecting path, the protecting path can be
used to transport other (extra) traffic.

You can read more about protection schemes in ITU-T recommendations
G.841 and G.808.1 (freeley available via the ITU-T site).

Cheers, Huub.
--
reply to hhelvooort with 2 'o's
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http://www.van-helvoort.eu/
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Always remember that you are unique...just like everyone else...
john reinhold
2007-09-16 05:39:01 UTC
Permalink
Dear Azhar, Huub,

Thank you for the immediate reply.

I would like to further my questions for Q1.

a. If I have one equipment that supports:
Higher order cross connect : 384 X384 VC4
Lower order cross connect:
384 X 384 VC3
2016 X 2016 VC12

the equipment is set as a ADM to perform the following tasks:
- Add and drop 630 VC12; Pass through 63 VC12
- Add and drop 2 VC3; Pass through 5 VC3
- Pass through 5 x STM-16 line equipment

Does it mean that the equipment has utlized the following?
High Order cross connect: 80 X 80 VC4
Lower order cross connect:
7X 7 VC3
693 X 693 VC12

And the remaining cross connect capability left in the equipment is
as follows?
High Order Cross connect: 304 X 304 VC4
Lower order cross connect:
377 X 377 VC3
1323 X 1323 VC12

Is this how I shalll calculate to decide which capacity of the
equipment can fulfill my site requirement?
In the above case, does the calculation imply that I shall get a
equipment with smaller capacity?

b. What is non-blocking?

c. Is grooming is equivalent to cross connect?

Thank you for all helps!

Regards,
John :)
Post by John Reinhold
Dear all,
I am new to the SDH equipment and seeking for some advices for the
1. There are a lot descriptions about SDH product that stating
a. 16 X 16 VC4
b. 8 X 8 VC4 non blocking cross connection
c. cross connect VC4/VC3/VC12 which equivalent to 64X 64 VC4.
What are those really mean and how can one accurately calculate how
much matrix capacity he or she will need?
2. There are two protection method that keep me confused: 1+1 and
1:N. What are the differences between two?
Please kindly help out!
Thanks a lot.
Raymond
--
Via: http://www.jumlers.com/comp.dcom.sdh-sonet/
--
Via: http://www.jumlers.com/comp.dcom.sdh-sonet/
Huub van Helvoort
2007-09-16 20:29:28 UTC
Permalink
Hello again John,
Post by john reinhold
I would like to further my questions for Q1.
Higher order cross connect : 384 X384 VC4
Lower order cross connect: 384 X 384 VC3
2016 X 2016 VC12
This is a big piece of equipment!
Post by john reinhold
- Add and drop 630 VC12;
This requires at least 10 VC-4 because they can also come
from partially filled VC-4s
Post by john reinhold
Pass through 63 VC12
This requires more than 1 VC-4 because they will come from
partially filled VC-4s and passed to other partially
filled VC-4s (worst case 63)
Post by john reinhold
- Add and drop 2 VC3;
This requires more than 1 VC-4 (a VC-4 can take up to 3 VC-3)
they may be dropped/added from 2 different VC-4
Post by john reinhold
Pass through 5 VC3
This requires at least 2 VC-4, worst case they may come from
5 different VC-4 and passed to 5 other VC-4.
Post by john reinhold
- Pass through 5 x STM-16 line equipment
This requires 80 VC-4s
Post by john reinhold
Does it mean that the equipment has utlized the following?
High Order cross connect: 80 X 80 VC4
No, it requires at least 94 X 94 VC-4 in the HO CC and
worst case 384 X 384 VC-4 in the HO CC.
Post by john reinhold
Lower order cross connect: 7 X 7 VC3 and 693 X 693 VC12
Right.
Post by john reinhold
And the remaining cross connect capability left in the equipment is
as follows? High Order Cross connect: 304 X 304 VC4
This is the best case, but as I mention above, it can be
much less.
Post by john reinhold
Lower order cross connect: 377 X 377 VC3
1323 X 1323 VC12
Right.
Post by john reinhold
Is this how I shalll calculate to decide which capacity of the
equipment can fulfill my site requirement?
You have to take into acouint that the LO VC-3 and VC-12
also need VC-4 for their transport which require capacity
in the HO CC.
Post by john reinhold
In the above case, does the calculation imply that I shall get a
equipment with smaller capacity?
No, if you want to utilise later more tributary slots you
need the full HO CC capacity.
Post by john reinhold
b. What is non-blocking?
That you can always make a connection through the CC.
I.e. connect the last available input to the last free output
without having to change some of the existing connections.
A square matrix is non-blocking, in a multistage matrix
(2 or more matrixes in series) blocking can occur.
Post by john reinhold
c. Is grooming is equivalent to cross connect?
Grooming is changing existing connections in a multistage
CC to enable adding another connection.
See also http://en.wikipedia.org/wiki/Clos_network.

Cheers, Huub.
--
reply to hhelvooort with 2 'o's
================================================================
http://www.van-helvoort.eu/
================================================================
Always remember that you are unique...just like everyone else...
Azhar
2007-09-17 15:29:16 UTC
Permalink
Post by Huub van Helvoort
Hello again John,
Post by john reinhold
I would like to further my questions for Q1.
Higher order cross connect : 384 X384 VC4
Lower order cross connect: 384 X 384 VC3
2016 X 2016 VC12
This is a big piece of equipment!
Post by john reinhold
- Add and drop 630 VC12;
This requires at least 10 VC-4 because they can also come
from partially filled VC-4s
Post by john reinhold
Pass through 63 VC12
This requires more than 1 VC-4 because they will come from
partially filled VC-4s and passed to other partially
filled VC-4s (worst case 63)
Post by john reinhold
- Add and drop 2 VC3;
This requires more than 1 VC-4 (a VC-4 can take up to 3 VC-3)
they may be dropped/added from 2 different VC-4
Post by john reinhold
Pass through 5 VC3
This requires at least 2 VC-4, worst case they may come from
5 different VC-4 and passed to 5 other VC-4.
Post by john reinhold
- Pass through 5 x STM-16 line equipment
This requires 80 VC-4s
Post by john reinhold
Does it mean that the equipment has utlized the following?
High Order cross connect: 80 X 80 VC4
No, it requires at least 94 X 94 VC-4 in the HO CC and
worst case 384 X 384 VC-4 in the HO CC.
Post by john reinhold
Lower order cross connect: 7 X 7 VC3 and 693 X 693 VC12
Right.
Post by john reinhold
And the remaining cross connect capability left in the equipment is
as follows? High Order Cross connect: 304 X 304 VC4
This is the best case, but as I mention above, it can be
much less.
Post by john reinhold
Lower order cross connect: 377 X 377 VC3
1323 X 1323 VC12
Right.
Post by john reinhold
Is this how I shalll calculate to decide which capacity of the
equipment can fulfill my site requirement?
You have to take into acouint that the LO VC-3 and VC-12
also need VC-4 for their transport which require capacity
in the HO CC.
Post by john reinhold
In the above case, does the calculation imply that I shall get a
equipment with smaller capacity?
No, if you want to utilise later more tributary slots you
need the full HO CC capacity.
Post by john reinhold
b. What is non-blocking?
That you can always make a connection through the CC.
I.e. connect the last available input to the last free output
without having to change some of the existing connections.
A square matrix is non-blocking, in a multistage matrix
(2 or more matrixes in series) blocking can occur.
Post by john reinhold
c. Is grooming is equivalent to cross connect?
Grooming is changing existing connections in a multistage
CC to enable adding another connection.
See alsohttp://en.wikipedia.org/wiki/Clos_network.
Cheers, Huub.
--
reply to hhelvooort with 2 'o's
================================================================
http://www.van-helvoort.eu/
================================================================
Always remember that you are unique...just like everyone else...
Hi,
Huub has given you a detailed understanding. I love to read his book
on SDH.

In general, you don't need to count number of cross connections in
your equipment or worry whether they are exceeding cross switching
capacity.

It is not possible to put more cards (tirbutary or line) than its
cross switch capacity provided you have followed vendor's rules of
placing cards in appropriate slots. Some times multi-port cards may
create confusion but additional ports won't work as per vendor's
restrictions.

Some vendors also provide various cross switch cards of different
capacities to be used within same node. So same node can have
different cross switching capacities.

Azhar
john reinhold
2007-09-18 14:16:02 UTC
Permalink
Hi Huub, Azhar,

Thanks a lot for the guidance !

One more questions, and I think by giving example will really help
me to understand better. It goes as follow:
- Equipment: 384 X 384 HO CC capacity, 384 X 384 VC3,
john reinhold
2007-09-18 14:19:01 UTC
Permalink
Hi Huub, Azhar,

Thanks a lot for the guidance !

One more questions, and I think by giving example will really help
me to understand better. It goes as follow:
- Equipment: 384 X 384 HO CC capacity, 384 X 384 VC3, 2016 X2016 LO
capacity

- If I have to drop 16 E1 (using 4 x VC4) from West direction (A
Fiber port);
- and 4 E1 (using 1 X VC4) in East direction (B Fiber Port)

The total capacity left shall be as follow?
380 X 383 VC4 OR 379 X 379 VC4 ( Shall I care about the Fiber Port
direction?)
384 X 384 VC3
2000 X 2012 OR 1996 X 1996 VC12 ( Shall I care about the Fiber Port
direction?)

Please kindly advise.

Thank you once again !

Regards
John
Huub van Helvoort
2007-09-18 18:17:20 UTC
Permalink
Hello John,
Post by john reinhold
One more questions, and I think by giving example will really help
- Equipment: 384 X 384 HO CC capacity, 384 X 384 VC3, 2016 X2016 LO
capacity
- If I have to drop 16 E1 (using 4 x VC4) from West direction (A
Fiber port); - and 4 E1 (using 1 X VC4) in East direction (B Fiber Port)
The total capacity left shall be as follow?
380 X 383 VC4 OR 379 X 379 VC4 ( Shall I care about the Fiber Port
direction?)
You have to keep in mind that normally traffic is bi-directional,
so if a signal is dropped, it is inserted as well. So a bi-directional
signal always requires an input and an output.

379 X 379 is the right answer in this case.
In case of uni-directional traffic where in this example
4 + 1 VC-4 are dropped the answer is 379 X 384, etc.
Post by john reinhold
384 X 384 VC3
Yes,
Post by john reinhold
2000 X 2012 OR 1996 X 1996 VC12
for bi-directional 1996 X 1996.
Post by john reinhold
Shall I care about the Fiber Port direction?
No, not really.

Keep in mind your network configuration and how
the forward and return path are provisioned.

In a ring topology traffic always runs in the same
direction:
received from east side, passed throught to west side
or dropped and inserted in west direction, and v.v.

In a linear topology traffic is passed through from
east to west or v.v.
traffic from east is dropped and inserted to east
traffic from west is dropped and inserted to west

Cheers, Huub.
--
reply to hhelvooort with 2 'o's
================================================================
http://www.van-helvoort.eu/
================================================================
Always remember that you are unique...just like everyone else...
john reinhold
2007-09-19 16:07:01 UTC
Permalink
Hi Huub,

Thank you for all the support !
I have learnt a lot from you.

Regards,
John

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