Configuring Keepalives

By default, physical interfaces configured with Cisco HDLC or PPP encapsulation send keepalive packets at 10-second intervals. The Frame Relay term for keepalives is LMI packets; the JUNOS software supports both ANSI T1.617 Annex D LMIs and ITU Q933 Annex A LMIs. On ATM networks, OAM cells perform the same function. You configure OAM cells at the logical interface level; for more information, see Defining the ATM OAM F5 Loopback Cell Period.

To disable the sending of keepalives on a physical interface, include the no-keepalives statement at the [edit interfaces interface-name] hierarchy level:

[edit interfaces interface-name]

no-keepalives; 

When you configure PPP over ATM or Multilink PPP over ATM encapsulation, you can enable or disable keepalives on the logical interface. For more information, see Configuring PPP over ATM2 Encapsulation.

To explicitly enable the sending of keepalives on a physical interface, include the keepalives statement at the [edit interfaces interface-name] hierarchy level:

[edit interfaces interface-name]

keepalives; 

To change one or more of the default keepalive values, include the appropriate option at the [edit interfaces interface-name] hierarchy level:

[edit interfaces interface-name]

keepalives <interval seconds> <down-count number> <up-count number>;

On interfaces configured with Cisco HDLC or PPP encapsulation, you can include the following three keepalive statements; note that Frame Relay encapsulation is not affected by these statements:

• interval seconds—The time in seconds between successive keepalive requests. The range is from 1 second through 32767 seconds, with a default of 10 seconds.
• down-count number—The number of keepalive packets a destination must fail to receive before the network takes a link down. The range is from 1 through 255, with a default of 3.
• up-count number—The number of keepalive packets a destination must receive to change a link's status from down to up. The range is from 1 through 255, with a default of 1.

For information about Frame Relay keepalive settings, see Configuring Frame Relay Keepalives.