Verilink Red Zone Encryption (REMS) (880-502423-001) Product Manual - Manual (Page 33)

System operation
Red Zone Encryption Management System (REMS) User Manual 3-7
Alignment
sequence The alignment sequence is as follows:
1. The near-end FBR sends all ones (no framing bit) to the encryptor.
The all-ones stream is encrypted, and this cipher text is passed to the
BRC.
2. The near-end BRC inserts an initial ESF framing bit onto the cipher
text by overwriting a bit at a random location. Additional ESF
framing bits are inserted in every subsequent 386th bit.
3. This ESF-framed cipher text is passed through the network to the far-
end BRC. This signal passes through the BRC unchanged and goes to
the far-end encryptor, where it is decrypted to restore the original all-
ones signal. Some of the bits which were inserted (overwritten) show
up as errors —zeros where all ones were expected. The position of
the errors is noted.
Without further processing, the payload data would be errored
sporadically in the inserted bit position.
4. Using this information, the far-end FBR identifies the near-end
framing sequence generated by the near-end BRC and synchronizes
to it.
5. By sending FBR code, the far-end FBR signals the near-end FBR that
it has synchronized to the framing sequence of the near-end
(transmitting) BRC.
Time
I BRC
I
I = BRC inserted bit