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Configuration Guide
Contivity Secure IP Services Gateway
Frame Relay on Contivity Secure IP Services Gateway
Command/response bit (C/R)
ITU-T (formerly CCITT) standards do not use this bit.
Forward explicit congestion notification (FECN) and backward explicit congestion notification (BECN)
The FECN and BECN indicate congestion on the network. For information about how the frame relay software uses these bits, see “Congestion Control”.
Discard eligibility (DE)
The DE bit allows the router to mark specific frames as low priority (discard eligible) before transmitting them to the frame relay network.
Extended address bit (EA)
The EA bit signals whether the next byte is part of the address. This bit indicates the last byte of the DLCI.
Management protocols
Frame relay is an access protocol that runs between a CES or data terminal equipment (DTE) and a switch or data communications equipment (DCE). The CES and the switch use the Data Link Control Management Interface (DLCMI) to exchange information about the interface and the status of each virtual circuit.
DLCMI supports three standard data link management specifications: LMI, ANSI T1.617 Annex D, and CCITT (now
•The networking industry first developed the local management interface (LMI) specification. The LMI approach is asymmetric; the router sends a
•ANSI modified the LMI specification and incorporated it as Annex D to ANSI standard T1.617. The ANSI method is generally similar to the LMI approach.
•The CCITT (now
Be sure to configure the frame relay interface on the CES to use the same management protocol as the switched network to which it is connected.
CG030601 | 2.00 | July 2003 | Page: 2 of 14 |