Configuring the Bandwidth Subscription Percentage for LSPs
By default, RSVP allows all of a class type’s bandwidth (100 percent) to be used for RSVP reservations. When you oversubscribe a class type for a multiclass LSP, the aggregate demand of all RSVP sessions is allowed to exceed the actual capacity of the class type.
If you want to oversubscribe or undersubscribe all of the class types on an interface using the same percentage bandwidth, configure the percentage using the subscription statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section.
To undersubscribe or oversubscribe the bandwidth for each class type, configure a percentage for each class type (ct0, ct1, ct2, and ct3) option for the subscription statement. When you oversubscribe a class type, an LOM is applied to calculate the actual bandwidth reserved. See Class Type Oversubscription and Local Oversubscription Multipliers for more information.
For a list of hierarchy levels at which you can include this statement, see the statement summary section.
percentage is the percentage of class type bandwidth that RSVP allows to be used for reservations. It can be a value from 0 through 65,000 percent. If you specify a value greater than 100, you are oversubscribing the interface or class type.
The value you configure when you oversubscribe a class type is a percentage of the class type bandwidth that can actually be used. The default subscription value is 100 percent.
You can use the subscription statement to disable new RSVP sessions for one or more class types. If you configure a percentage of 0, no new sessions (including those with zero bandwidth requirements) are permitted for the class type.
Existing RSVP sessions are not affected by changing the subscription factor. To clear an existing session, issue the clear rsvp session command. For more information on the clear rsvp session command, see the Junos OS Operational Mode Commands.
Constraints on Configuring Bandwidth Subscription
Be aware of the following issues when configuring bandwidth subscription:
- If you configure bandwidth constraints at the [edit class-of-service interface interface-name] hierarchy level, they override any bandwidth configuration you specify at the [edit protocols rsvp interface interface-name bandwidth] hierarchy level for Diffserv-TE. Also note that either of the CoS or RSVP bandwidth constraints can override the interface hardware bandwidth constraints.
- If you configure a bandwidth subscription value for a specific interface that differs from the value configured for all interfaces (by including different values for the subscription statement at the [edit protocols rsvp interface interface-name] and [edit protocols rsvp interface all] hierarchy levels), the interface-specific value is used for that interface.
- You can configure subscription for each class type only
if you also configure a bandwidth model. If no bandwidth model is
configured, the commit operation fails with the following error message:
user@host# commit check[edit protocols rsvp interface all] 'subscription' RSVP: Must have a diffserv-te bandwidth model configured when configuring subscription per traffic class. error: configuration check-out failed
- You cannot include the subscription statement
both in the configuration for a specific class type and the configuration
for the entire interface. The commit operation fails with the following
error message:
user@host# commit check[edit protocols rsvp interface all] 'subscription' RSVP: Cannot configure both link subscription and per traffic class subscription. error: configuration check-out failed
