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List of terms
Nortel Multiservice Switch 7400/15000/20000
Terminology
NN10600-005 7.2S1 Standard
PCR7.2 and up March 2006
Copyright © 2006, Nortel Nortel Confidential
backbone router
A router that has an interface to the backbone, including area border routers
(ABR). A backbone router that has connections only to other backbone
routers also functions as an internal router.
backplane
The printed circuit board into which control and function processors on a shelf
are seated. The backplane serves two functions: distributes power to all
processor cards on the shelf, and supports the bus that transports data and
signaling between processor cards.
backplane bus
A cell-based 800 Mbit/s bus. The backplane bus allows each processor card
in a shelf to send data or signaling to any other processor card. There are two
backplane buses for each shelf: X and Y.
backplane control system (BCS)
The software system that manages the operation of the Nortel Multiservice
Switch 15000 and Multiservice Switch 20000 fabrics. The BCS controls the
fabrics on each processor card, allowing applications to send and receive
frames over the backplane X and Y fabrics. The BCS also monitors the state
of the fabrics to ensure that all cards can communicate. Lastly, the BCS allows
the operator to monitor and test the fabrics.
backplane fabric
A cell-based 56.3 Gbit/s fabric. The backplane fabric allows each processor
card in a shelf to send data or signaling to any other processor card. There
are two backplane fabrics for each shelf: X and Y.
backplane file system (BFS)
The file system that enables a processor card to access files on either the
active or standby control processor across the backplane.
backward congestion indication (BCI)
A bit in the Nortel Multiservice Switch packet header that indicates that
packets travelling in the opposite direction on the connection are encountering
congestion.
backward explicit congestion notification (BECN)
The bit in a frame relay header that indicates congestion in the path for the
direction opposite to the direction in which the frame is flowing.
backward resource management cell (BRM)
Forward resource management cells that the ABR destination device turns
around for delivery to the available bit rate source. See forward resource
management cell (FRM) (page 54).