Chapter 2. Technical description 37
2.4 Hubbed-ring network configuration
In the hubbed-ring configuration, shelves in the remote sites have a one-to-one
correspondence with shelves in the hub site, according to their allocated shelf
band pairs. The pair of shelves are allocated to the same band wavelength (Band
1 through Band 8). The shelf band wavelengths can be arbitrary, but must be
unique within the network.
Figure 30 on page 38 shows an example of an IBM 2029 network in the
hubbed-ring configuration. It consists of a hub site with four IBM 2029 shelves
connected through a fiber pair ring to four remote shelves.
The shelves in each site are interconnected using single-mode fiber-optic jumper
cables (also known as pigtails). These jumper cables connect the OMX West
modules in the hub site to each other, and the OMX East modules in the hub site
to each other.
The two fiber pairs running between the hub site and the remote sites are
connected to an OMX module in the first and last shelves at the hub site. The first
fiber pair (transmit and receive) connects the OMX East module in the Band 1
hub shelf with the OMX West module in the Band 4 remote shelf. The second
fiber pair (transmit and receive) connects the OMX West module in the Band 4
hub shelf with the OMX East module in the Band 1 remote shelf.
The OMX West and OMX East modules of each remote site shelf are
interconnected using fiber-optic pigtails.
The network traffic flow for Figure 30 (using ADF, shown in Figure 22 on
page 30), is as follows:
We called all signals originating or destined for the East side of all shelves in the
hub site E-Bx, and for the West side W-Bx (x being the respective band number).
1. Starting from Band 1 East side at the hub site, the E-B1 signal gets added. All
signals (E-B1, B2, B3, B4) are sent out (OTS OUT) to remote site Band 4
West side.
2. Band 4 receives the signals through OTS IN, the E-B4 signal gets dropped,
then all other signals (E-B1, B2, B3) are passed (THRU OUT) to Band 4 East
side (THRU IN), W-B4 signal gets added and E-B1, B2, B3, and W-B4 get sent
out (OTS OUT) to remote site Band 3 West side.
3. Band 3 receives the signals through OTS IN, the E-B3 signal gets dropped,
then other all signals (E-B1, B2, and W-B4) are passed (THRU OUT) to Band
3 East side (THRU IN), W-B3 signal gets added and E-B1, B2, and W-B3, B4
get sent out (OTS OUT) to remote site Band 2 West side.
4. Band 2 receives the signals through OTS IN, the E-B2 signal gets dropped,
then all other signals (E-B1 and W-B4, B3) are passed (THRU OUT) to Band 2
East side (THRU IN), W-B2 signal gets added and E-B1 and W-B2, B3, B4 get
sent out (OTS OUT) to remote site Band 1 West side.
5. Band 1 receives the signals through OTS IN, the E-B1 signal gets dropped,
then other all signals (W-B2, B3, B4) are passed (THRU OUT) to Band 1 East
side (THRU IN), W-B1 signal gets added and W-B1, B2, B3, B4 get sent out
(OTS OUT) to the hub site Band 4 West side.
38 Fiber Saver (2029) Implementation Guide
6. Band 4 at the hub site receives W-B1, B2, B3, B4 signals through OTS IN,
drops the W-B4 signal and passes (THRU OUT) all other signals to Band 3
West side, and so on, until each signal gets dropped by its respective band.
In the opposite direction the flow is the same, only in reverse order.
Figure 30. IBM 2029 hubbed-ring network
A hubbed-ring network may have up to eight shelves in the hub site and eight
remote shelves. The remote shelves site locations may be one shelf each in
eight remote sites, or fewer multishelf remote sites, or all shelves in one remote
site. The maximum fiber distance supported between the hub site and the furthest
remote site shelf is 35 km.
WE
I
T
O
O
O
I
T
O
I
T
O
O
O
I
T
O
Band 1
Band 3
Band 4
I
T
O
O
O
I
T
O
W
E
W
E
WE
4A 1B
1A 4B
I
T
O
O
O
I
T
O
I
T
O
O
O
I
T
O
Band 2
WE
I
T
O
O
O
I
T
O
I
T
O
O
O
I
T
O
W
E
I
T
O
O
O
I
T
O
I
T
O
O
O
I
T
O
Band 4
Band 3
Band 2
Band 1
W
E
I
T
O
O
O
I
T
O
I
T
O
OO
I
T
O
I
T
O
OO
I
T
O
I
T
O
OO
I
T
O
I
T
O
OO
I
T
O
I
T
O
OO
I
T
O
1A
2A
3A
4A
1A
2A
3A
4A
1A
2A
3A
4A
2A
3A
1A
4A
1B
2B
3B
4B
1B
2B
3B
4B
1B
2B
3B
4B
2B
3B
1B
4B
I
T
O
OO
I
T
O
WE
1A 4B
1A 4B
1A
4B
First fiber pair
Second fiber pair
Hub Shelves
Remote Shelves
E-B1
drop
E-B1
add
W-B1
drop
W-B1
drop
W-B1
add
W-B1
add
E-B1
add
E-B1
drop
OCI
OCI
E-B1
W-B1
W-B1
E-B4
E-B4
E-B3, B4
E-B3, B4
E-B2, B3, B4
E-B2, B3, B4
W-B1, B2
W-B1, B2
W-B1, B2, B3
W-B1, B2, B3
E-B1, B2, B3, B4
W- NONE
E-B1,B2,B3,B4
W- NONE
W-B1, B2, B3, B4
E- NONE
W-B1, B2, B3, B4
E- NONE
W- B4
E-B1,B2,B3
W- B4
E - B1, B2, B3
E-NONE
W- B1, B2, B3, B4
E-NONE
W-B1,B2,B3,B4
W- B2, B3, B4
E-B1
W- B2, B3, B4
W- B3, B4
E-B1,B2
W- B3, B4
E-B1,B2
O
I
OTS IN
O
O
OTS OUT
I
T
THRU IN
T
O
THRU OUT
W
E
OMX East
OMX West
one fiber

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