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Configuring MPLS
decremented once by the ingress LSR and once by the egress LSR. When disabled, the
MPLS TTL is set to 255 by the ingress LSR and is independent of the IP TTL.
When
is enabled, each LSR is viewed as a router hop (from an IP
propagate-ip-ttl
TTL perspective). When a packet traverses an LSP, it emerges with the same TTL value
that it would have had if it had traversed the same sequence of routers without being
label-switched. When enabled, the MPLS TTL field is initially set by the IP TTL field at
the ingress LSR, and the IP TTL field is set to the MPLS TTL by the egress LSR.
Configuring Penultimate Hop Popping
To enable or disable PHP, use the following command:
config mpls php [enabled | disabled]
This command enables or disables whether PHP is requested by the egress LER.
When PHP is enabled, PHP is requested on all LSPs for which the switch is the egress
LER.
PHP is requested by assigning the Implicit Null Label in an advertised mapping. PHP is
always performed when requested by an egress LSR (for example, when the switch is
acting as an intermediate LSR). The Implicit Null Label is always used in conjunction
with routes exported by OSPF, regardless of the PHP configuration.
This command can only be executed when MPLS is disabled. The default setting is
disabled.
Configuring QoS Mappings
To configure QoS mappings, use the following command:
config mpls qos-mapping [dot1p-to-exp | exp-to-dot1p] [all |
<input_value>]/<output_value>
This command configures MPLS QoS mappings. If
is specified, all input values are
all
mapped to the specified
. The valid range of integers for the
<output_value>
and the
is 0 to 7. By default, the mapping tables are
<input_value>
<output_value>
initialized such than an
of n is mapped to an
of n.
<input_value>
<output_value>
MPLS Module Installation and User Guide
3-17
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