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Glossary

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split horizon

Useful for preventing routing loops, a type of distance-vector

routing rule where information about routes is prevented from leaving the
router interface through which that information was received.

spoofing

1) In dial-on-demand routing (DDR), where a circuit-switched

link is taken down to save toll charges when there is no traffic to be sent,
spoofing is a scheme used by routers that causes a host to treat an interface
as if it were functioning and supporting a session. The router pretends to
send "spoof" replies to keepalive messages from the host in an effort to con-
vince the host that the session is up and running. See also: DDR. 2) The
illegal act of sending a packet labeled with a false address, in order to deceive
network security mechanisms such as filters and access lists.

spooler

A management application that processes requests submitted to it

for execution in a sequential fashion from a queue. A good example is a print
spooler.

SPX

Sequenced Packet Exchange: A Novell NetWare transport protocol

that augments the datagram service provided by Network layer (Layer 3)
protocols, it was derived from the Switch-to-Switch Protocol of the XNS
protocol suite.

SQE

Signal Quality Error: In an Ethernet network, a message sent from a

transceiver to an attached machine that the collision-detection circuitry is
working.

SRB

Source-Route Bridging: Created by IBM, the bridging method used in

Token-Ring networks. The source determines the entire route to a destina-
tion before sending the data and includes that information in route informa-
tion fields (RIF) within each packet. Contrast with: transparent bridging.

SRT

source-route transparent bridging: A bridging scheme developed by

IBM, merging source-route and transparent bridging. SRT takes advantage
of both technologies in one device, fulfilling the needs of all end nodes.
Translation between bridging protocols is not necessary. Compare with:
SR/TLB.

SR/TLB

source-route translational bridging: A bridging method that

allows source-route stations to communicate with transparent bridge sta-
tions aided by an intermediate bridge that translates between the two bridge
protocols. Used for bridging between Token Ring and Ethernet. Compare
with: SRT.

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