Juniper JUNOSE 11.1.X - LINK LAYER CONFIGURATION 4-7-2010, Configuration Manual

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The number of successive loopback cell responses missed before the router
determines that the circuit is down
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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 19.
F5 loopback receive and transmit statistics are available with “show atm vc atm” on
page 94 .
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:
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F5 segment loopback cells or end-to-end loopback cells, issue the ping atm
command on a VC.
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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.
Operations, Administration, and Management of ATM Interfaces
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Chapter 1: Configuring ATM