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DES-7200 Configuration Guide Chapter 1 MPLS Configuration
1-23
DES-7200(config-mpls-router)#
lsp-control-mode {independent |
orderd}
Set the label distribution control mode.
DES-7200(config-mpls-router)# no
lsp-control-mode
Restore the default label distribution control
mode.
Configuring the LDP Label Distribution Mode
The LDP label distribution mode specifies how an LSR notifies its neighbors of the binding
between labels and FECs. There are two modes: DOD and DU.
In DOD mode, a downstream LSR responds to a label binding message only after the receipt of
a label request from an upstream LSR neighbor. In DU mode, one LSR voluntarily sends label
binding messages to its upstream LSRs according to certain triggering policies. If the upstream
and downstream LSRs use different label distribution modes, use the DU mode if the LSRs are
connected to each other through Ethernet.
By default, the LDP works in DU mode. You can use the distribution-mode command in the
interface mode to set the label distribution mode on an interface.
Command Function
DES-7200(config-if-type ID)# mpls ldp
distribution-mode {du | dod}
Set the label distribution mode.
DES-7200(config-if-type ID)# no mpls
ldp distribution-mode
Restore the default label distribution mode (DU).
Configuring the LDP Label Retention Mode
The label retention mode specifies whether an LSR should retain the label binding learnt from a
label mapping message if the message is not sent from the next hop of the corresponding FEC
or the message does not match any existing IP route. There are two label retention modes:
conservative and liberal modes.
When the preceding situation occurs, the liberal mode retains the binding of the FEC and label
from the neighbor whereas the conservative mode does not retain the binding information.
The conservative label retention mode uses and maintains a small number of labels. The LSR
should reobtain the label values in the case of route changes, prolonging responses. The liberal
label retention mode, however, responds rapidly to route changes but unnecessary label
mappings are also distributed and maintained.