Using DDR, low-volume, periodic network connections can be made CCIE Exams(http://www.cathayschool.com) over the PSTN. A routeractivates the DDR feature when
it receives a bridged or routed IP packet destined for a location on the other side of the dial-up line. After the router dials the destination phone number
and establishes the connection, packets of any supported protocol can be transmitted. When the transmission is complete, the line is automatically
disconnected. By terminating unneeded connections, DDR reduces cost of ownership.
Encapsulation (Tunneling) Encapsulation takes packets or frames fromone network systemand places theminside frames from another network system. This method
is sometimes called tunneling. Tunneling provides a means for encapsulating packets inside a routable protocol via virtual interfaces. Synchronous Data Link
Control (SDLC) transport is also an encapsulation of packets in a routable protocol. In addition, transport provides enhancements to tunneling, such as local
data-link layer termination, broadcast avoidance, media conversion, and other scalability optimizations. Cisco routers support the following encapsulation
and tunneling techniques:
The IBM technology feature set provides these methods:
— Serial tunneling (STUN) or Synchronous Data Link Control (SDLC) Transport
— SRB with direct encapsulation
— SRB with Fast Sequenced Transport (FST) encapsulation
— SRB with Transmission Control Protocol/Internet Protocol (TCP/IP) encapsulation
— Data Link Switching Plus (DLSw+) with ccie routing and switching training(http://www.cathayschool.com/ccie-routing-and-switching-1-on-1-classes.html)
encapsulation
— DLSw+ with TCP/IP encapsulation
— DLSw+ with Fast Sequenced Transport/Internet Protocol (FST/IP) encapsulation
— DLSw+ with DLSw Lite (Logical Link Control Type 2 [LLC2]) encapsulation
• Generic Routing Encapsulation (GRE)
Cisco supports encapsulating Novell Internetwork Packet Exchange (IPX), Internet Protocol(IP), Connectionless Network Protocol (CLNP), AppleTalk, DECnet
Phase IV, Xerox Network Systems (XNS), Banyan Virtual Network System (VINES), and Apollo packets for transport
over IP
• Single-protocol tunneling techniques:ccie service provider lab(http://www.cathayschool.com/ccie-security-1-on-1-classes.html) (AppleTalk over IP), AURP
(AppleTalk over IP),
EON (CLNP over IP), and NOS (IP over IP)
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