The set-overload command sets the overload bit for non-pseudonode LSPs.
The undo set-overload command removes the overload bit of non-pseudonode LSPs.
By default, no overload bit is set for non-pseudonode LSPs.
set-overload [ on-startup [ timeout1 | start-from-nbr system-id [ timeout1 [ timeout2 ] ] | wait-for-bgp [ timeout1 ] ] [ send-sa-bit [ timeout3 ] ] ] [ allow { interlevel | external }* ]
undo set-overload
| Parameter | Description | Value |
|---|---|---|
on-startup |
Indicates that the overload bit remains set within the specified period when the switch restarts or is faulty. |
- |
timeout1 |
Specifies the duration of the overload bit after the system starts. |
The value is an integer that ranges from 5 to 86400, in seconds. The default value is 600 seconds. |
start-from-nbr system-id |
Specifies the duration of the system overload bit according to the status of a specified neighbor. |
The value is in XXXX.XXXX.XXXX format. |
timeout1 [ timeout2 ] |
Specifies the period during which the overload bit remains set, which is related to the neighbor status. |
|
wait-for-bgp |
Specifies the period during which the overload bit of the system remains set according to the BGP convergence status. |
- |
send-sa-bit |
Specifies the overload bit remains in Hello packets after the device is started. |
- |
timeout3 |
Specifies the period during which the overload bit remains in Hello packets after the device is started. |
The value is an integer ranging from 5 to 120, in seconds. The default value is 30 seconds. |
allow |
Allows advertising IP prefixes. By default, the system is prohibited from advertising IP prefixes when the system enters the overload state. |
- |
interlevel |
Allows advertising the IP prefixes learned from IS-IS of different levels when allow is specified. |
- |
external |
Allows advertising the IP prefixes learned from other protocols when allow is specified. |
- |
Usage Scenario
Although LSPs with the overload bit are flooded on the network, the LSPs are ignored in the calculation of the routes that pass through the switch in overload state. That is, after the overload bit is set on the switch, other switches ignore the switch when performing SPF calculation. Direct routes of the switch are not ignored during SPF calculation.
To prevent the local switch from being used by other switches to perform SPF calculation, run the set-overload command on the local switch without specifying the on-startup keyword. Then the system immediately sets the overload bit in the LSP to be sent. To remove the overload bit, run the undo set-overload command.
When the local switch restarts or is faulty, to prevent the local switch from being used by other switches to perform SPF calculation, run the set-overload command on the local switch and specify the on-startup keyword.
When the switch is experiencing memory shortage, the system automatically sets the overload bit in the sent LSPs regardless of whether the set-overload command is run.
You can set the overload bit to solve the problem of network traffic loss caused by the difference between the BGP convergence speed and IGP convergence speed.
Precautions
If a TE LSP uses the local device as a transit node before the set-overload command is run, the TE LSP is not torn down and re-established and still uses the local device as a transit node after the set-overload command is run; if the local device is restarted after the command is run and fast convergence is not configured on the ingress of the RSVP-LSP, TE LSP forwarding fails, and services are affected. Therefore, the mpls te path-selection overload command needs to be run on the ingress of the RSVP-LSP before the device is restarted.