Verilink 9000 Series (34-00271) Product Manual - Manual (Page 335)

Definitions of Commonly Used Terms 313
Definitions of
Commonly Used
Terms The following frequently used terms are defined below.
Adjacency
(NLSP only)
A relationship formed between selected neighboring routers for exchanging routing
information. Not every pair of neighboring routers become adjacent.
Circuit or
Interface
The connection between a router and one of its attached networks. An interface has
state information associated with it, which is obtained from the underlying lower
level protocols and the routing protocol itself.
Designated
Router
(NLSP only)
Each multi-access network that has at least two attached routers has a designated
router. The designated router generates a link state advertisement for the
multi-access network and has other special responsibilities for running the
protocol. The designated router is elected by the HELLO Protocol.
The designated router concept enables a reduction in the number of adjacencies
required on a multi-access network. This in turn reduces the amount of routing
protocol traffic and the size of the topological database.
HELLO
Protocol
(NLSP only)
The part of the NLSP protocol used to establish and maintain neighbor
relationships. On multi-access networks the HELLO Protocol can also dynamically
discover neighboring routers.
Link State
Packet
(NLSP only)
Describes the local state of a router or network. This includes the state of the
route’s interfaces and adjacencies. Each link state advertisement is flooded
throughout the routing internetwork. The collected link state advertisements of all
routers and network forms the protocol's topological database.
Lower-level
protocols
The underlying network access protocols that provide services to the Internet
Protocol and in turn the NLSP protocol. Examples of these are the X.25 packet and
frame levels for X.25 PDNs, and the Ethernet data link layer for Ethernets.
Multi-access
Networks
Those physical networks that support the attachment of multiple (more than two)
routers. Each pair of routers on such a network is assumed to be able to
communicate directly (e.g., multi-drop networks are excluded).
Neighboring
Routers
(NLSP only)
Two routers having interfaces to a common network. On multi-access networks,
neighbors are dynamically discovered by the NLSP Protocol.
Network Mask
(NLSP only)
A 32-bit number indicating the range of IPX addresses.
Router Routers interconnect different network segments and by definition are network
layer devices.