# PPP, MLPPP, and Cisco HDLC Options

After you configure an interface for PPP or Cisco HDLC encapsulation in the interface's Basic Properties, you can configure keepalive options.

- To configure PPP keepalive options, click PPP.

  To configure keepalive options:

  1. Enter the following:

  Keepalive: Select this option to have the interface send keepalive packets to its peer.

  Keepalive Interval: Enter the interval, in seconds, at which keepalive packets are sent.

  Down Counter: Enter the number of successive times that a destination fails to receive keepalive packets before the link is considered to be down.

  2. Click Apply.

- To configure Cisco HDLC keepalive options, click Cisco HDLC.

  To configure keepalive options:

  1. Enter the following:

  Keepalive: Select this option to have the interface send keepalive packets to its peer.

  Keepalive Interval: Enter the interval, in seconds, at which keepalive packets are sent.

  Down Counter: Enter the number of successive times that a destination fails to receive keepalive packets before the link is considered to be down.

  Up Counter: Enter the number of successive times that a destination receives a keepalive packet before the link is considered to be up.

  2. Click Apply.

After you create a multilink interface and configure it for MLPPP encapsulation, you can configure MLPPP options for the bundle.

- To configure MLPPP options, click MLPPP.

  To configure MLPPP options for a multilink interface (also called a bundle):

  1. Enter the following:

  Drop Timeout: Enter the timeout, in milliseconds, for bundle links that drop one or more packets. A value of 0 means that drop timeout is disabled.

  Minimum Links: Enter the minimum number of bundle links that must be up for the bundle to be considered up.

  Maximum Received Reconstructed Unit: Enter the maximum packet size, in bytes, that the bundle can process..

  Fragment Threshold: Enter the maximum size, in bytes, for packet payloads transmitted across individual links within the multilink circuit.

  Short-Sequence MLPPP Number: Select this option to use a sequence header format of 12 bits. Deselect this option to use a sequence header format of 24 bits.

  2. Click Apply.