Services
7750 SR OS Services Guide Page 97
The user can also configure how long the service manager must wait before it must revert the SDP
to a higher priority LSP type when one becomes available by using the following command:
config>service>sdp mpls>mixed-lsp-mode>sdp-revert-time seconds
A special value of the timer dictates that the SDP must never revert to another higher priority LSP
type unless the currently active LSP type is down:
config>service>sdp mpls>mixed-lsp-mode>sdp-revert-time infinite
The BGP LSP type will also be allowed. In other words, you will also be able to configure the
bgp-tunnel [bgp-lbl-prd] command under the SDP concurrently with the lsp and ldp commands.
Mixed-LSP Mode of Operation
At any given time, the service manager programs only one type of LSP in the IOM that will
activate it to forward service packets according to the following priority order:
1. RSVP LSP type. Up to 16 RSVP LSPs can be entered by the user and programmed by the
service manager in ingress IOM to load balance service packets. This is the highest priority
LSP type.
2. LDP LSP type. One LDP FEC programmed by service manager but ingress IOM can use
up to 16 LDP ECMP paths for the FEC to load balance service packets when ECMP is
enabled on the node.
The service manager will program the NHLFE(s) for the active LSP type preferring the RSVP
LSP type over the LDP LSP type.
If no RSVP LSP is configured or all configured RSVP LSPs go down, the service manager will re-
program the IOM with the LDP LSP if available. If not, the SDP goes operationally down.
When a higher priority type LSP becomes available, the service manager reverts back to this LSP
at the expiry of the sdp-revert-time timer or the failure of the currently active LSP, whichever
comes first. The service manager then re-programs the IOM accordingly. If the infinite value is
configured, then the SDP reverts to the highest priority type LSP only if the currently active LSP
failed.
Note however, that LDP uses a tunnel down damp timer which is set to three seconds by default.
When the LDP LSP fails, the SDP will revert to the RSVP LSP type after the expiry of this timer.
For an immediate switchover this timer must be set to zero. The command for this timer is
configure>router>ldp>tunnel-down-damp-time
If you change the value of the sdp-revert-time timer, it will take effect only at the next use of the
timer. Any timer which is outstanding at the time of the change will be restarted with the new
value.
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