
Customizing Frame Relay
114058 Rev. A 3-5
If you are connecting two routers back to back, use one of the DTE parameter
options (Rev 1 LMI, ANSI T1.617D, CCITT Annex A) for the router acting as a
DTE, and one of the DCE options (LMI Switch, Annex D Switch, Annex A
Switch) for the router acting as the DCE. Although you can configure the router
for the DCE side of a connection, the router cannot act as a full switch, and it will
not perform complete bidirectional signaling.
The LMI Switch, Annex D Switch, and Annex A Switch options are primarily for
troubleshooting.
Selecting Address Type and Length
You can specify the DLCI address type and length that the router and the Frame
Relay network use to direct packets to their destinations. The address type for the
router and for the switch must be the same.
Selecting a DLCI Address Type
Your options for the DLCI address type follow.
• ADDR Q922 selects addressing as specified in the final version of the Q.922
standard. Q.922 provides for FECN, BECN, DE, and EA bits. While most
Q.922 addresses are included within a 2-octet field, the standard allows for 3-
and 4-octet address fields. This is the default.
• The November draft of ADDR Q922 differs from ADDR Q922 in dropping
the D/C bit from the extended (3- and 4-byte) forms. The D/C bit (DLCI or
DL-Core Control Indication) is always 0.
• The March draft of ADDR Q922 differs from ADDR Q922 in defining an
11-bit DLCI and dropping the DE bit from the second octet of the address
field.
• ADDR Q921 differs from ADDR Q922 MARCH 90 in that it does not use
FECNs or BECNs, which means that it does not provide congestion control.
Site Manager: Mgmnt Type parameter: page A-2
Site Manager: Address Type parameter: page A-3
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