| X.25 encapsulation is typically
seen in a packet-switched environment. LAPB is the data link
protocol used to encapsulate X.25 packets. X.25 evolved in the days of analog
circuits when error rates were much higher than today, so
reliability was built into the X.25 framework.
X.25 can transport LAN packets end-to-end through a packet-switched
network. A Virtual Circuit (VC) is established, and LAN datagrams
use the connection-oriented reliable-transfer X.25 packet switching.
Like X.25, Frame Relay is an industry-standard
data link layer protocol that is commonly used in packet-switched
networks. Frame
Relay is a well-understood, connection-oriented service that relies
on digital switching to achieve very respectable throughput. Frame
Relay supports technological advances such as fiber-optic cabling
and digital transmission.
Frame Relay circuits run over more reliable
types of data links, such as fiber optic links and higher quality
circuits, and thus don't require the complex error correction that
is needed with older, less reliable WAN media types. Since error
correction and flow control are time consuming processes, Frame
Relay links of a given speed can be more efficient than equal speed
links of other types.
Customers
purchase a committed information rate from the carrier to ensure
their minimum bandwidth requirements are met. Additional DS0
channels can be easily added to meet growth requirements. Because
you are using a public network, you must consult with your service
provider and obtain information specific to your link.
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