Verilink Red Zone Encryption (REMS) (880-502423-001) Produc Manual de usuario descargar pdf (Pagina 39)

How the BRC communicates with the FBR

Red Zone Encryption Management System (REMS) User Manual

3-13

Table 3-1 Decoding the 4-bit Message Field

Message bit #

1234 Site Code or Message State

1011

FBR Code

The FBR code, placed in the offset frame bit positions, is sent from the far-end

FBR.

0 1 1 0

Encrypted FBR Code

As it passes through the encryptor, the FBR code is encrypted.

⇓

Originating BRC performance message

Network performance data is coded as a BRC performance message, ready to

be inserted and sent to the near-end Access Manager 2000.

1011

Combined encrypted FBR code and BRC performance message

The encrypted FBR code and the BRC performance message are combined into

one message using a 2-input exclusive-OR function. Simply, for each bit

position, if the bit values which are being combined are:

• different, the resulting value is “1

• the same, the resulting value is “0”

0 1 1 0

Decrypted FBR code (with inserted BRC performance message

As the exclusive-OR’ed text passes through the encryptor, it is decrypted to

produce this result. Remember that the decryption key has now been applied to a

message which was created from encrypted FBR code and a plain text BRC

performance message, so the result will differ from original exclusive-OR’ed text.

⇓

Local FBR reference code

The local FBR refers to the FBR code it was expecting.

1101

Resulting BRC performance message

The FBR extracts the BRC message by using a second exclusive-OR function to

compare the received code with the FBR reference code. Simply, each bit

position is compared to the expected value. If the result of the comparison is:

• different, the output is a “1”

• the same, the output is a “0”

The resulting message is the same as the original BRC performance message

created in .

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Verilink Red Zone Encryption (REMS) (880-502423-001) Produc Manual de usuario Pagina 39