Fiber Saver (2029) Implementation Guide

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

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O

O

O

I

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O

Band 2

WE

I

T

O

O

O

I

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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

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Band 4

Band 3

Band 2

Band 1

W

E

I

T

O

O

O

I

T

O

I

T

O

OO

I

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O

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T

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OO

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OO

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OO

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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

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OO

I

T

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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