FL SWITCH SFN…

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As an example, if a total of four switches are connected

together, there will be a first switch then three additional

switched segments. This means that three times the

overhead value must be used.

4.

Add all the application traffic (step 2.) with all the over

head values (step 3.) and compare with the total

available bandwidth.

Example 1

Assuming gigabit devices are used with 9000-byte jumbo

frames and a total of three cascaded switches. Each switch

has one 8 bit/pixel camera plus 10 Mbps of miscellaneous

traffic from other ports.

Figure 14 depicts an example with three cameras

connected to individual switches. Each camera is

configured for an 8 bits per pixel color depth, creating a

load of 182 Mbps per camera (see Table 2) with a total

traffic load of 546 Mbps. Frame size is configured to 9000

bytes creating an overhead of 180 Mbps (see Figure 13) for

each cascading switch for a total of 360 Mbps.

Figure 14

9000-byte frame size example

Adding the camera data and overhead together indicates a

total traffic load of 906 Mbps, leaving 94 Mbps of the

1000 Mbps total unused.

Example 2

To take advantage of the bandwidth not used in example 1,

assume one of the cameras is now required to operate at

12 bits per pixel.

The increased camera color depth increases the traffic load

to a total of 639 Mbps. Combined with the 360 Mbps

overhead with a 9000-byte frame size, the total bandwidth is

999 Mbps. While technically within the capability of a

1000 Mb switch, any additional traffic across the

transmission line could result in frame loss.

Figure 15

8000-byte frame size example

One possible solution is to change the frame size to

8000 bytes, reducing the overhead (see Figure 15). The

reduced frame size results in a total overhead of 320 Mbps.

Combined with the camera traffic load, the resulting

bandwidth requirement is 959 Mbps, allowing some space

for additional traffic.

input

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HP LP 2065

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Ord.-No.: 2891929

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FL SWITCH SFN 8TX

Ord.-No.: 2891929

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182 Mbps

182 Mbps

182 Mbps

180 Mbps

180 Mbps

input

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HP LP 2065

X1

X3

X5

X7

FL SWITCH SFN 8TX

Ord.-No.: 2891929

100

LNK/

AC

T

100

LN

K/

AC

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FL SWITCH SFN 8TX

Ord.-No.: 2891929

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FL SWITCH SFN 8TX

Ord.-No.: 2891929

100

LNK/

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182 Mbps

182 Mbps

275 Mbps

160 Mbps

160 Mbps