Terminating Stale Pppoa Subscribers And Restarting Lcp Negotiations - Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010 Configuration Manual

Terminating Stale PPPoA Subscribers and Restarting LCP Negotiations

In configurations of dynamic IP over dynamic PPP over a static ATM 1483
subinterface, as shown in Figure 45 on page 529, any of the following conditions
might cause the static ATM 1483 subinterface to transition to a dormant state as the
result of an ungraceful subscriber logout:
When the ATM 1483 subinterface transitions to a dormant state as a result of any
of these conditions, the router tears down the dynamic PPP interface column. The
dynamic PPP interface is unable to send an LCP terminate request to its peer because
its own lower-layer interface is down. This action causes a loss of connectivity between
the router and the PPPoA customer premises equipment (CPE). If the CPE supports
the PPP keepalive feature, it can detect the loss of connectivity and restart Link
Control Protocol (LCP) negotiations in order to initiate a new connection. However,
if the CPE does not support PPP keepalive, it cannot detect that the connection is
down, and continues to send PPP data packets to the router.
On receipt of an IPv4-over-PPP data packet or an IPv6-over-PPP data packet from
the CPE when the ATM 1483 subinterface transitions to a dormant state, the router
sends an LCP terminate request packet to the CPE. Receipt of the LCP terminate
request packet causes the CPE to restart LCP negotiations in order to initiate a new
connection. After the CPE restarts LCP negotiations, the router recreates the dynamic
PPP and IP upper-layer interfaces above the static ATM 1483 subinterface. This
behavior is always in effect on the router and does not require CLI or SNMP
configuration.
Sending an LCP terminate request packet in response to receipt of an IPv4-over-PPP
data packet or an IPv6-over-PPP data packet from a PPPoA CPE device offers the
following benefits:
Use the no version to remove a profile assignment.
See profile.
Rebooting the router
Rebooting a line module
Transitioning the physical (for example, SONET) interface, ATM major interface,
or ATM AAL5 interface from up to down to up again
Transitioning the ATM 1483 subinterface or the ATM PVC from up to down to
up again
Any other lowerLayerDown operational status condition that affects the dynamic
PPP interface; a lowerLayerDown status indicates that a lower-layer interface
below the dynamic PPP interface is down
For CPEs that support PPP keepalive, receipt of an LCP terminate request packet
from the router restarts the LCP negotiations more quickly.
For CPEs that do not support PPP keepalive, receipt of an LCP terminate request
packet from the router enables the CPE to detect the connection termination
and restart LCP negotiations in response.
Configuring PPP and PPPoE Dynamic Interfaces over Static ATM
Chapter 17: Configuring Dynamic Interfaces
533