Chapter 3. Configuration61200659L1-1 MX2800 STS-1 User Manual 3-7External Clock ConfigurationPRI Ext. Clock and SEC Ext. Clock - When timing is set toexternal, these entries allow selection of the primary and secondaryclock source. Any one of the 28 ports, so long as it is active, can beused. If the selected port does go into AIS or LOS, the selectedclock becomes invalid.VT INTERFACEThe VT INTERFACE menu (shown in Figure 3-4 on page 3-7) allowsyou to activate/deactivate individual T1s and E1s and to set theirline coding, length, loopback detection, circuit protection, and lineID string. The T1/E1 code violation threshold is also configuredthrough this menu. Configuration selections are described in thesections following Figure 3-4 on page 3-7.Figure 3-4. VT Interface MenuA VT group can be divided into either three E1s or four T1s. Therefore,when dealing with an E1 configuration, some of the fields in the VTINTERFACE menus do not apply (and therefore display N/A).
