Glossary of iseend ch4

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Created by jds3000

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DS1 (T1):
DS3 (T3):
J1 (Y1):
hdlc: FACTDF
the bytes in an HDLC frame:
flag(1 byte) address(1 byte) control(1 byte) type(2 bytes) data(variable bytes) FCS(4 bytes)
WAN term: synchronous...
time ordering on a bit stream. 1 device tries to use the same speed as another on the end of a serial link. The device examines transitions btwn voltage on the link, device can notice variations in speed and adjust accordingly.
WAN term: clock source...
the device to which other devices on the link adjust their speed when using synchronous links.
WAN terms: CSU/DSU...
channel service unit / data service unit. It's an interface to the telco. Routers are connected to it w/short cable from serial interface, attached to the telco's line.
WAN terms: Telco...
telephone company
ch4 terms: access link...
in Frame Relay...the physical serial link that connects a router to frame relay switch. same physical layer standards as point to point leased lines.
ch4 term: clocking...
supplying a signal over cable so that the receiving device can keep synchronized with the sending device.
ch4 term: DTE (layer 1)...
Data Terminal Equipment. In layer 1's view, the DTE syncs its clock based on the clock sent by the DCE. In packet-switching's view, the DTE is the device outside the svc provider's network, like a router.
ch4 term: CSU/DSU...
channel service unit / data service unit. Device that understands the layer 1 details of serial links installed by a telco and how to use a serial cable to comm' with networking equip such as routers.
ch4 term: DCE (layer 1)...
Data Communications Equipment. Layer 1's view: provides the clocking on a WAN link. The CSU/DSU is the DCE. Packet switching's view: the svc provider's switch to which a router would connect; considered the DCE.
ch4 term: frame relay...
a standard data-link protocol; defines frame switching/packet switching; allows DTE devices (routers) to send data to many other devices using a single physical connection to the frame relay service.
ch4 term: leased line...
a serial circuit btwn 2 points, provided by svc provider. Charges monthly fee to send bits btwn the 2 sites; considered to be a leased svc.
ch4 term: packet switching...
WAN service; examines the contents of data to make a forwarding decision. Contrasts with "frame" switching: provider sets up a circuit btwn 2 devices, makes no attempt to interpret the meaning of the bits.
ch4 term: PPP...
point to point protocol. provides connections over circuits.
ch4 term: serial cable...
type of cable with many different styles of connectors to connect a router to an external CSU/DSU on a leased line installation.
ch4 term: virtual circuit...
In Frame Relay, the ability of routers send/receive data directly to each other. Provides the same function of a leased line, but without a physical circuit.

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