Juniper JUNOSE 11.2, Руководство по настройке

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•
The number of successive loopback cell responses missed before the router determines
that the circuit is down
• The number of successive loopback responses received before the router determines
that the circuit is up
VC integrity is a best-effort mechanism that tries to adhere to the loopback cell
transmission frequency and retry frequency values configured for each VC without
consuming excessive processing time on the line module. When you configure VC integrity
for a large number of circuits on the line module, delays in transmitting OAM loopback
cells might occur so new subscribers can connect and to maintain existing subscriber
connections.
To set up the ATM interface to transmit F5 end-to-end loopback cells over a VC, use the
oam keyword and an optional frequency with the atm pvc command. To send F5 segment
loopback cells, use the ATM ping mechanism, described in “ATM Ping” on page 18.
F5 loopback receive and transmit statistics are available with “show atm vc atm” on
page 90 .
F4 OAM Cells
You can generate F4 loopback cells using the atm oam command or the ATM ping
mechanism. F4 loopback receive and transmit statistics are available with the show
atm oam command and include statistics on incoming and outgoing F4 end-to-end and
segment loopback cells.
ATM Ping
With ATM ping you can verify whether a connection endpoint or segment point can be
reached on a VC or VP. ATM ping uses F4 and F5 loopback cells and is supported only
for data circuits and not control circuits (ILMI, signaling circuits). To generate:
•
F5 segment loopback cells or end-to-end loopback cells, issue the ping atm command
on a VC.
• F4 segment loopback cells or end-to-end loopback cells, issue the ping atm command
on a VP.
You can specify the number of loopback cells that are sent, the location ID, and the timer
value. After the interface sends the loopback cells, the timer is started and the interface
waits for a response. On receiving the loopback response (or when the timer expires) the
ATM interface sends the next cell. This operation is repeated for the number of cells
specified.
Because F4 and F5 are OAM cells, disabling receipt and transmission of OAM cells on
the ATM interface (by using the
atm oam flush command) stops all outstanding ping
operations on the ATM interface. You need to manually restart the ping operation after
you enable receipt and transmission of OAM cells for the interface.
How the ATM Interface Handles Loopback Cells Received
The ATM interface responds to received F4 and F5 loopback cells as indicated in Table
6 on page 19.
Copyright © 2010, Juniper Networks, Inc. 18
JunosE 11.2.x Link Layer Configuration Guide