?– Switched virtual circuit (SVC): Provides temporary connections that are used in
situations that require only sporadic data transfer between DTE devices across the
Frame Relay network. SVCs are dynamically established on demand and are torn
down when transmission is complete.
?– Data-link connection identi?¬?er (DLCI): Contains a 10-bit number in the address
?¬?eld of the Frame Relay frame header that identi?¬?es the VC. DLCIs have local
signi?¬?cance because the identi?¬?er references the point between the local router and the
local Frame Relay switch to which the DLCI is connected. Therefore, devices at
opposite ends of a connection can use different DLCI values to refer to the same virtual
connection.
?– Committed information rate (CIR): Speci?¬?es the maximum average data rate that
the network undertakes to deliver under normal conditions. When subscribing to a
Frame Relay service, you specify the local access rate, for example, 56 kbps or T1.
Typically, you are also asked to specify a CIR for each DLCI. If you send information
faster than the CIR on a given DLCI, the network ?¬‚ags some frames with a discard
eligible (DE) bit. The network does its best to deliver all packets but discards any DE
packets ?¬?rst if congestion occurs.
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