this chapter. If you are already comfortable with the topics in this chapter, this summary could
help you recall a few details. If you have just read this chapter, this review should help solidify
some key facts. If you are doing your final preparation before the exam, Tables 10-2 through
10-3 are a convenient way to review the day before the exam.
mode terminals) that do not support the full functionality of a particular protocol to a
network. PADs buffer data and assemble and disassemble packets sent to such end devices.
network. In the basic Frame Relay specification, DLCIs are locally significant.
successor to RIP in the Internet community. OSPF features include least-cost routing,
multipath routing, and load balancing. OSPF was derived from an early version of the IS-IS
protocol.
Relay
using HDLC encapsulation between connected devices. Frame Relay is more efficient than
X.25, the protocol for which it is generally considered a replacement.
remote terminal access and computer communications in PDNs. X.25 specifies LAPB, a data
link layer protocol, and PLP, a network layer protocol.
LMI includes support for a keepalive mechanism, which verifies that data is flowing; a
multicast mechanism, which provides the network server with its local DLCI and the
multicast DLCI; global addressing, which gives DLCIs global rather than local significance
in Frame Relay networks; and a status mechanism, which provides an ongoing status report
on the DLCIs known to the switch.
DTE receiving the frame that congestion was experienced in the path from source to
destination. DTE receiving frames with the FECN bit set can request that higher-level
protocols take flow-control action as appropriate.
traveling in the opposite direction of frames encountering a congested path. DTE receiving
frames with the BECN bit set can request that higher-level protocols take flow control action
as appropriate.