Glossary | P |
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PNNI Routing Hierarchy
The hierarchy of peer groups used for PNNI routing.
PNNI Topology State Packet
A type of PNNI Routing packet that is used for flooding PTSEs among logical nodes within a peer group.
POH
Path Overhead: A maintenance channel transmitted in the SONET overhead following the path from the beginning multiplexer to the ending demultiplexer. This is not implemented in SONET Lite.
Point-to-Multipoint Connection
A
•One ATM link, called the Root Link, serves as the root in a simple tree topology. When the Root Node sends information, all of the remaining nodes on the connection, called Leaf Nodes, receive copies of the information.
•Each of the Leaf Nodes on the connection can send information directly to the Root Node. The Root Node cannot distinguish which Leaf is sending information without additional (higher layer) information. (See note below for User Network Interface (UNI) 4.0 support)
•The Leaf Nodes cannot communicate directly to each other with this connection type.
Note: UNI 4.0 does not support traffic sent from a Leaf to the Root.
A connection with only two endpoints.
Port Identifier
The identifier assigned by a logical node to represent the point of attachment of a link to that node.
Partial Packet Discard (PPD)
Partial Packet Discard (PPD) is a congestion control technique that drops all of the ATM cells in a Classical IP over ATM packet. When congestion occurs and any one cell of a particular frame is dropped, PPD discards the rest of the cells (since the frame is errored and will need to be sent again anyway).
Centillion 1200N ATM Switch User Manual | |
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