Configuring T1 Interfaces

To configure properties on a T1 interface:

  1. From the configuration page, as shown in Figure 1, select the T1 interface you want to configure.

    The properties you can configure on a T1 interface are displayed, as shown in Figure 7.

    Figure 7: T1 Interfaces Configuration Page

    T1 Interfaces Configuration Page
  2. Enter information into the configuration page, as described in Table 10.
  3. Click one of the following buttons:
    • To apply the configuration and stay on the Configure Interfaces page, click Apply.
    • To apply the configuration and return to the configuration page that lists all interfaces, click OK.
    • To cancel your entries and return to the Configure Interfaces page, click Cancel.

Table 10: T1 Configuration Summary

Field

Function

Your Action

Logical Interfaces

Add logical interfaces

Defines one or more logical units that you connect to this physical T1 interface. You must define at least one logical unit for a T1 interface. You can define multiple units if the encapsulation type is Frame Relay.

Click Add.

Logical Interface Description

(Optional) Describes the logical interface.

Type a text description of the logical interface to more clearly identify it in monitoring displays.

IPv4 Addresses and Prefixes

Specifies one or more IPv4 addresses for the interface.

  1. Click Add.
  2. Type one or more IPv4 addresses and prefixes. For example:

    10.10.10.10/24

  3. Click OK.

Physical Interface Description

(Optional) Adds supplementary information about the physical T1 interface.

Type a text description of the T1 interface to more clearly identify it in monitoring displays.

MTU (bytes)

Specifies the maximum transmission unit (MTU) size for the T1 interface.

Type a value between 256 and 9192 bytes. The default MTU for T1 interfaces is 1504.

Clocking

Specifies the transmit clock source for the T1 line.

From the list, select one of the following:

  • internal—Device's own system clock (the default)
  • external—Clock received from the T1 interface

Per Unit Scheduler

Enables scheduling on logical interfaces.

Allows you to configure multiple output queues on a logical interface and associate an output scheduler and shaping rate with the queues.

  • To enable scheduling, select the check box.
  • To disable scheduling, clear the check box.
Encapsulation

Encapsulation

Specifies the encapsulation type for traffic on the interface.

From the list, select the encapsulation for this T1 interface:

  • PPP
  • Frame Relay
  • Cisco HDLC

Enable CHAP

Enables or disables CHAP authentication on a T1 interface with PPP encapsulation only.

  • To enable CHAP, select the check box.
  • To disable CHAP, clear the check box.
CHAP Local Identity (available if CHAP is enabled)

Use System Host Name

Specifies that the T1 interface uses the device's system hostname in CHAP challenge and response packets.

  • To enable, select the check box (the default).
  • To disable, clear the check box.

Local Name

If Use System Host Name is disabled, specifies the local name for CHAP to use.

Type a local name for this T1 interface.

CHAP Peer Identity

Identifies the client or peer with which the device communicates on this T1 interface.

Type the CHAP client name.

CHAP Secret

Specifies the secret password for CHAP authentication, known to both sides of the connection.

Type a password that is known to the other side of the connection. Use a combination of letters and numbers that is difficult for others to guess.

T1 Options

BERT Algorithm

Specifies the bit error rate test (BERT) algorithm to use during a BERT. BERT is supported only when transmission is unframed. (See the Unframed option.)

From the Bert Algorithm list, select the algorithm to use:

  • all-ones-repeating
  • alternating ones-zeros
  • all-zeros-repeating
  • pseudo-2e11–o152
  • pseudo-2e15–o151
  • pseudo-2e20–o151
  • pseudo-2e20–o153
  • pseudo-2e23–o151
  • pseudo-2e29
  • pseudo-2e31
  • pseudo-2e9–o153

BERT Error Rate

Specifies the exponent n in the bit error rate 10–n.

Type a value between 3 and 7, or 0. For example, a value of 6 specifies that 1 bit out of 1,000,000 is transmitted in error. The default is 0 (no bits are transmitted in error).

BERT Period

Specifies the length of time, in seconds, of the BERT.

Type a value between 1 and 240. The default is 10.

Byte Encoding

Specifies the byte encoding method.

From the list, select one of the following:

  • nx56—7 bits per byte
  • nx64—8 bits per byte (the default)

Frame Checksum

Specifies the number of bits in the frame checksum. A 32-bit checksum provides more reliable packet verification, but is not supported by some older equipment.

Select 16 or 32. The default checksum is 16.

Framing Mode

Specifies the framing mode for the T1 line.

From the list, select one of the following:

  • g704—The default
  • g704–no-crc4—G704 without cyclic redundancy check 4 (CRC4)
  • unframed—Unframed transmission format

Invert Data

Enables or disables data inversion. Data inversion is normally used only in alternate mark inversion (AMI) mode.

  • To enable, select the check box.
  • To disable, clear the check box.

Line Encoding

Specifies the line encoding method.

From the list, select one of the following:

  • ami—Alternate mark inversion
  • b8zs—Binary 8 zero substitution (the default)

Loopback

Configures the T1 interface as a loopback interface for testing purposes.

When T1 is configured as a local loopback interface, the device transmits test traffic simultaneously to the CSU and to the receiver at the T1 interface.

When T1 is configured as a remote loopback interface, test traffic transmitted by the CSU is simultaneously received at the T1 interface and transmitted back to the CSU.

From the Loopback list, select one of the following:

  • local—Traffic loops from the transmitter to the receiver at the T1 interface during tests.
  • remote—Traffic loops from the receiver to the transmitter at the T1 interface during tests.

Timeslots

Specifies the number of time slots allocated to a fractional T1 interface. By default, an T1 interface uses all the time slots.

Type numeric values from 2 through 32. Separate discontinuous entries with commas, and use hyphens to indicate ranges. For example:

2,4,7–9

T3 Options

Frame Checksum

Specifies the number of bits in the frame checksum. A 32-bit checksum provides more reliable packet verification, but is not supported by some older equipment.

Select 16 or 32. The default value is 16.

Enable Long Buildout

Specifies a short or long cable length for copper-cable-based T3 interfaces. A long cable is longer than 225 feet (68.6 m).

  • To enable long buildout, select the check box.
  • To disable long buildout, clear the check box.

Disable C-Bit Parity Mode

Enables or disables C-bit parity mode, which controls the type of framing that is present on the transmitted T3 signal.

  • To disable, select the check box.
  • To enable, clear the check box.