Precedence Levels For Dynamic Pvcs; Precedence Level Examples; Upgrade Considerations - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - LINK LAYER CONFIGURATION GUIDE 2010-10-13 Configuration Manual

Upgrade Considerations

Copyright © 2010, Juniper Networks, Inc.

Precedence Levels for Dynamic PVCs

For PVCs that are dynamically created, the router determines the PVC attribute values
according to the following precedence levels, in order from highest precedence to lowest
precedence:
The attribute value specified in the VC class assigned in the base profile always has
1.
the highest precedence.
If no VC class is assigned in the base profile, the router takes the value for that attribute
2.
from the VC class assigned to the associated ATM major interface.
If neither the base profile nor the ATM major interface has a VC class assigned, the
3.
router takes the value for that attribute from the individually specified attributes in
the base profile.
If neither the base profile nor the ATM major interface has a VC class assigned, and
4.
no attributes are individually specified in the base profile, the router applies the default
values for the commands listed in Table 8 on page 57. For information about the
default value for each command, see the command descriptions in "Configuring VC
Classes" on page 56.

Precedence Level Examples

For examples that illustrate how precedence levels affect the assignment of VC classes,
see "Precedence Level Examples for Assigning VC Classes" on page 64.
To help you better understand these examples, we recommend that you first read the
following sections to learn how to configure and assign VC classes:
The following considerations apply to using ATM VC classes when you upgrade to the
current JunosE Software release from a lower-numbered JunosE Software release:
It is possible to use VC classes for PVCs created in a lower-numbered release with the
atm pvc command. In such cases, the router uses the following rules to determine the
PVC attribute values:
Nondefault values explicitly specified for PVC attributes with the atm pvc command
take precedence over the attribute values specified in the associated VC class. As a
result, the router takes the values for these attributes from the atm pvc command
settings.
Default values implicitly specified for PVC attributes with the atm pvc command
have a lower precedence than the attribute values specified in the associated VC
class. As a result, the router takes the values for these attributes from the assigned
VC class.
The output of the show configuration command uses either the pvc command format
or the atm pvc command format to display ATM PVCs. The display format of
configuration information for ATM PVCs created with the atm pvc command depends
on the JunosE Software release from which you are upgrading, as follows:
Chapter 1: Configuring ATM
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