After Cc Cell Flow Is Enabled; Loopback; Vc Integrity - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - LINK LAYER CONFIGURATION GUIDE 2010-10-13 Configuration Manual

Loopback

Copyright © 2010, Juniper Networks, Inc.

After CC Cell Flow Is Enabled

If the VC or VP is set up as the source point, the ATM interface sends one CC cell per
second. CC cell generation stops if one of the following conditions occur:
The ATM interface goes down.
You disable OAM CC on the circuit by using the atm pvc command.
The peer deactivates the OAM CC cell flow.
You disable OAM cell reception and transmission on the ATM interface by using the
atm oam flush command.
If the VP is set up as a CC sink point and no CC cell is received for 4 seconds, the VP goes
to AIS state and sends one RDI cell per second.
To view the current state of the activation or deactivation process, including statistics,
use the show atm oam command for VPs and the show atm vc atm interface command
for VCs.
You can use loopback cells to verify connectivity between VP/VC endpoints, as well as
segment endpoints within the VP/VC. You can use these tests to perform fault isolation
over the VP/VC.
The ATM interface supports VC integrity, which generates F5 end-to-end loopback cells.
It also supports ATM ping, which generates F4 and F5 segment and end-to-end loopback
cells to test the reachability of an endpoint or a segment endpoint.

VC Integrity

VC integrity is used to monitor the operational status of an individual VC. VC integrity
provides continuous ATM VC-layer connectivity verification by periodically sending F5
end-to-end loopback cells on individual PVCs to verify end-to-end connectivity. You can
set the frequency with which loopback cells are transmitted for an individual VC.
If VC integrity is enabled, the peer ATM host must respond to the router's loopback cells,
or the circuit will be disabled. The ATM interface does not reenable the circuit until it
receives loopback responses or until local VC integrity is disabled.
You can set the following VC integrity parameters for an individual VC with the oam retry
command. For more information, see "oam retry" on page 52.
The retry frequency with which loopback cells are transmitted when the router verifies
the down status of the circuit; that is, when the peer ATM host does not respond to a
loopback cell
The retry frequency with which loopback cells are transmitted when the router verifies
the up status of the circuit; that is, when the ATM host resumes responding to a
loopback cell
Chapter 1: Configuring ATM
17