Description

The MPLS LSP configuration will not be committed, when the highest set-up priority is defined, instead of the hold priority value. You cannot configure an LSP with a high setup and a low reservation priority value.

Symptoms

Even when you try to configure the high set up priority, rather than the hold priority, for an RSVP signaled MPLS LSP, Junos CLI will not allow you to commit the configuration. It will  generate the Configuration Check-out failed error message, as shown below: 

lab:R1# show protocols mpls
label-switched-path LSP-1 {
    from 1.1.1.1;
    to 4.4.4.4;
    bandwidth 10g;
    no-cspf;
    priority 2 5;
}
interface all;

[edit]
lab:R1# commit check
[edit logical-systems R1 protocols mpls]
'label-switched-path LSP-1'
invalid priority value at '5' not in range 0 to 2
error: configuration check-out failed

Solution

  • As the default set up priority and Holding Priority values are 7 and 0 for an RSVP LSP, the RSVP signaling protocol will not allow you to manually lower the holding priority value to that of the setup priority value.

  • Either both the setup and holding priority values need to be the same or set-up priority should be less than the holding priority value.

Note : The priority is inversely proportional to numerical values.

Configure the low set-up priority, rather than the holding priority value, for the LSP to form.

edit protocols mpls label-switched-path LSP-1]
lab:R1# show
from 1.1.1.1;
to 4.4.4.4;
bandwidth 10g;
no-cspf;
priority 5 4;

[edit protocols mpls label-switched-path LSP-1]
lab:R1# commit check
configuration check succeeds
Alternatively, you can configure the set-up and holding priority to the same value, as shown below, for the LSP to form:
[edit protocols mpls label-switched-path LSP-1]
lab:R1# show
from 1.1.1.1;
to 4.4.4.4;
bandwidth 10g;
no-cspf;
priority 5 5;

[edit protocols mpls label-switched-path LSP-1]
lab:R1# commit
commit complete

[edit protocols mpls label-switched-path LSP-1]
lab:R1# top

[edit]
lab:R1# run show mpls lsp
Ingress LSP: 1 sessions
To          From         State      Rt    P        ActivePath       LSPname
4.4.4.4     1.1.1.1       Up         0    *                          LSP-1
Total 1 displayed, Up 1, Down 0

Egress LSP: 0 sessions
Total 0 displayed, Up 0, Down 0

Transit LSP: 0 sessions
Total 0 displayed, Up 0, Down 0

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