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Guidelines for Configuring VPI/VCI Ranges of ATM Virtual Circuits
Copyright © 2010, Juniper Networks, Inc.
The F5 Operations Administration and Maintenance (OAM) cells and Integrated Local
Management Interface (ILMI) cells are carried on the pseudowire because F5 OAM cells
arrive with the same VPI/VCI values as the data cells. In such cases, you can configure
the ILMI VPI/VCI as part of the range to enable the ILMI cells be carried on the pseudowire.
However, F4 OAM cells are not carried over the pseudowire because the router does not
enable opening of the VP-level OAM circuits to be transported transparently on the
pseudowire. Because only a subset of the ATM virtual circuits on an ATM port are carried
on the pseudowire, LDP uses the ATM n-to-one VCC cell transport (0x0009) pseudowire
(PW) type instead of the ATM transparent cell transport (0x0003) PW type in the
signaling messages.
Observe the following guidelines when you specify a single VPI/VCI range of ATM VCs
whose cells need to be transported on the single pseudowire:
Use to specify a single VPI/VCI range of ATM VCs whose cells need to be transported
on the single pseudowire.
You can configure the mpls-relay atm vpi-range vci-range command on the ATM port
only after you associated a pseudowire with the port by using the mpls-relay or route
interface tunnel command.
You can use this command only on an ATM port (ATM AAL5 over ATM major interface).
When you attempt to run this command on other interface types, such as ATM
subinterfaces or Ethernet interfaces, this setting is not saved and an error message is
displayed.
When you run the mpls-relay or route interface tunnel command, no default VPI/VCI
range is configured. You must specifically configure the VPI/VCI ranges.
The VPI/VCI values that are not part of the specified range can be used for other existing
applications. For example, you can configure an ATM subinterface on the same ATM
port with a VPI/VCI value that is not included by the specified range specification and
use that interface as an IP interface or subscriber interface.
If you configured a VPI/VCI range on the shim interface and try to configure an ATM
subinterface with the VPI/VCI value that is encompassed by the VPI/VCI range specified
earlier on the shim interface, an error message is displayed stating the VPI/VICI range
that you are trying to configure is already reserved and the configuration fails.
If some of the VPI/VCI values specified in the range are used for other applications,
the specified range is marked inactive and this setting is saved on the router, without
being used to transport traffic. You must remove the conflicting range, and remove or
reconfigure this range to activate it for transportation of ATM cells.
If the specified VPI/VCI range includes the F4 OAM VCI values, the range is saved. The
F4 OAM VCs are not opened, but the rest of the VCs are opened if they are not
configured for other applications. If some of the VCs other than the F4 OAM VCs are
opened for other applications, the range is marked inactive. You must specify ranges
that do not overlap with the F4 OAM VCI values.
Chapter 8: Layer 2 Services over MPLS Overview
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