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    Configuring T1 and E1 Port Parameters for VComp Bundles (CTP Menu)

    This topic describes how to configure port parameters for T1/E1 interfaces.

    Before you begin:

    • Disable the bundle before you modify the bundle options.

    To configure port parameters for T1/E1 interfaces for VComp bundles using the CTP Menu:

    1. From the Main Menu, select 1) Bundle Operations.
    2. Select 4) VCOMP.
    3. If you are creating a new VComp bundle on a T1/E1 interface module and there are no other bundles configured on the interface, you are prompted to specify whether the T1/E1 interface is dedicated to VComp bundles.
      Do you want to configure this card for all VCOMP?  y[n]:
      • If you specify yes, all ports on the interface can be used for VComp bundles, and you cannot configure any other bundle types on the interface.
      • If you specify no, you can configure other types of bundles on the interface. However, you cannot use port 2 for VComp bundles.
    4. If you are configuring an existing bundle, select a bundle from the list.

      If you select an active bundle, you are prompted to disable the bundle before configuring it.

    5. Select 3) Port Config.
    6. Follow the onscreen instructions, and configure the options as described in Table 1.

      The options vary depending on whether the bundle is T1 or E1.

    Note: BITS input is a T1/E1 line interface unit (LIU), with AMI (alternate mark inversion) encoding enabled and B8ZS/HDB3 (Zero Suppression) disabled. The equalization is set for a 0-133 feet cable. An internal 100 ohm termination is present, although it might need to be externally augmented based on the type of cabling used. Any valid AMI signal works properly and it is not restricted to only the "all 1" BITS signal but the ones density must be sufficient to prevent LOS (according to the ITU G.775 recommendation). The TTL input has a slice point of 3.3V/2 = 1.65V relative to chassis ground (GND). Therefore, any signal on the coaxial center conductor that transitions through that voltage registers a transition. There are many signals, besides TTL, that satisfy this criteria. An external termination must be provided that matches the impedance of the cable that goes to the BNC connector.

    If you can configure the rate in CTP menu, then the TTL supports a frequency of 2048 KHz for the TTL clock input, provided the signal is good and noise-free (terminated properly). TTL is rate-agile, while BITS is restricted to T1/E1 frequencies.

    The TTL input is high-impedance (no on-board termination provided) because a variety of cable types might exist that you can use to drive signal to this connector, such as RG-58 coax (50 ohm), RG-59 coax (75 ohm), or twisted pair (100-120 ohm). Instead of applying a particular impedance termination on the board and have it incorrectly done, we recommend that you configure the impedance termination based on your network environment. For example, a 50 ohm termination is needed if you are using RG-58/U coax cable, which has 50 ohm impedance.

    Table 1: VComp Bundle T1/E1 Port Parameter Settings in the CTP Menu

    FieldFunctionYour Action

    Port descriptor

    Specifies a description for the port.

    Enter a description of up to 62 alphanumeric characters. Do not use the following characters:

    ( ; ' " ) ]


    Specifies the type of interface.

    The type of interface that you select affects the default packet size and buffer sizes for the bundle.

    Select one:

    • T1
    • E1


    Specifies the T1 encoding method used on this bundle.

    Select one:

    • B8ZS
    • AMI


    For T1 interfaces, specifies the line buildout.

    Select one:

    • 0) ~133 ft
    • 1) ~266 ft
    • 2) ~399 ft
    • 3) ~533 ft
    • 4) ~655 ft
    • 5) -7.5dB CSU
    • 6) -15dB CSU
    • 7) -22.5dB CSU

    Frame Mode

    For T1 interfaces, specifies the framing method.

    Select one:

    • ESF—Extended Superframe (ESF) Framing. Frame synchronization, data link, and CRC framing bits are passed across the IP network untouched.
    • D4—Superframe Framing.

    Signal (for T1)

    For T1 interfaces, specifies whether or not CAS signaling is used.

    Enter one:

    • On—Signaling is on. Signaling lead input on each channel is transported end-to-end.
    • Off—Signaling is off.

    Signal (for E1)

    For E1 interfaces, specifies the signaling method used.

    Select one:

    • CSS—Common channel signaling. The common channel carries data messages that convey signaling for the circuits between two devices.
    • CAS—Channel associated signaling. Each traffic channel has a dedicated signalling channel (channel 16).

    Modified: 2015-05-20