PassFinder AP2520 VoIP Router/Gateway Operation Manual
Version 1.10 / Mar. 2002
AddPac Technology Co., Ltd.
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79
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4.5.3.
Frame-Relay Configuration
The frame-relay mode is a transmission method of the frame layer that is used in
the frame-relay data communication network. By connecting the WAN
(serial) port of the PassFinder AP2520 router to the DSU/CSU, the operator can
transmit frame-relay packets at the speed of T1/E1.
As the transmission line quality improves and error occurrence rate significantly
drops in the transmission line, the frame-relay minimizes various control functions
and the error recovery function which occupies significant amount of the
data-link layer, and implements only core functions that are necessary for data
transmission in the network. In this way, the frame-relay simplifies the
processing steps and enables the DTE to perform other functions. As a result,
the frame-relay is a kind of protocol that realizes high-speed transmission and
minimum delay.
The WAN (serial) port of the PassFinder AP2520 router that is set as the
frame-relay mode is applied to the physical layer and the data link layers
among OSI 7 layers. Data link layers include the Link Access Procedure on the
D channel (LAPD) complying with ITU-T Q.922 and Q.921 and the Link Access
Protocol for Frame Relay (LAPF) complying with ITU-T Q.922. The WAN (serial)
port can use several sub-interfaces in one physical link and use these
sub-interfaces as virtual circuits.
The frame-relay parameters include Data Link Connection Identifier (DLCI)
values that are frame-relay addresses. Communication network service
providers such as Korea Telecom or Dacom (in Korea) allocate these values.
The PassFinder AP2520 router supports both of static mapping and the
inverse-ARP in the frame-relay network. LMI types that the PassFinder AP2520
router supports are ANSI and Q.933a. The PassFinder AP2520 router also
complies with IETF(RFC1490) standard for the encapsulation method.
The PassFinder AP2520 router functions not only as a frame-relay access router
but also as a frame-relay switch. The PassFinder AP2520 router can be used
under Permanent Virtual Circuit (PVC) environment.
Information
