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D-10
Cisco ONS 15454 Installation and Operations Guide
November 2001
Appendix D Glossary
Ping
Packet internet grouper. ICMP echo message and its reply. Often used in IP networks to test the
reachability of a network device.
PPJC
positive pointer justification count
PPMN
Path Protected Mesh Network. PPMN extends the protection scheme of a unidirectional path switched
ring (UPSR) beyond the basic ring configuration to the meshed architecture of several interconnecting
rings.
Priority queuing
Routing feature that divides data packets into two queues: one low-priority and one high-priority.
Provisioning user
A security level that allows the user to access only provisioning and maintenance options in CTC. See
also Superuser, Maintenance user, and Retrieve user.
Q
Queue
In routing, a backlog of packets waiting to be forwarded over a router interface.
R
Red band
DWDM wavelengths are broken into two distinct bands: red and blue. The red band is the higher
frequency band. The red band DWDM cards for the ONS 15454 operate on wavelengths between
1547.72nm and 1560.61nm.
Retrieve user
A security level that allows the user to retrieve and view CTC information but not set or modify
parameters. See also Superuser, Maintenance user, and Provisioning user.
Revertive switching
A process that sends electrical interfaces back to the original working card after the card comes back
online.
Rising threshold
The number of occurrences (collisions) that must be exceeded to trigger an event.