RSVP protocol level

The operator enables DiffServ TE by executing the diffserv-te command in the config>router>rsvp context. When this command is enabled, IS-IS and OSPF start advertising available bandwidth for each TE class configured under the diffserv-te node. The operator can disable DiffServ TE globally by using the no form of the command.

The enabling or disabling of DiffServ on the system requires that the RSVP and MPLS protocol be shutdown. The operator must execute the no shutdown command in each context after all parameters under both protocols are defined. When saved in the configuration file, the no shutdown command is automatically inserted under both protocols to make sure they come up after a node reboot.

IGP advertises the available bandwidth in each TE class in the unreserved bandwidth TE parameter for that class for each RSVP interface in the system.

In addition, IGP continues to advertise the existing Maximum Reservable Link Bandwidth TE parameter so the maximum bandwidth that can be booked on a specific interface by all classes. The value advertised is adjusted with the link subscription factor configured in the config>router>rsvp>if>subscription percentage context.

The operator can overbook (underbook) the maximum reservable bandwidth of a CT by overbooking (underbooking) the interface maximum reservable bandwidth by configuring the appropriate value for the subscription percentage parameter.

The diffserv-te command only has effect if the operator has already enabled TE at the IS-IS and, or OSPF routing protocol levels:

config>router>isis>traffic-engineering

config>router>ospf>traffic-engineering

The following DiffServ TE parameters are configured globally under the diffserv-te node. They apply to all RSVP interfaces on the system. When configured, these parameters can only be changed after shutting down the MPLS and RSVP protocols:

Definition of TE classes, TE Class = {Class Type (CT), LSP priority}. Eight TE classes can be supported. There is no default TE class when DiffServ is enabled. The operator must explicitly define each TE class. However, when DiffServ is disabled there is an internal use of the default CT (CT0) and eight preemption priorities as shown in Table: Internal TE class definition when DiffServ TE is disabled.

Table: Internal TE class definition when DiffServ TE is disabled
Class type (CT internal)	LSP priority
0	7
0	6
0	5
0	4
0	3
0	2
0	1
0	0

A mapping of the system forwarding class to CT. The default settings are shown in Table: Default mapping of forwarding class to TE class.

Table: Default mapping of forwarding class to TE class
FC ID	FC name	FC designation	Class type (CT)
7	Network Control	NC	7
6	High-1	H1	6
5	Expedited	EF	5
4	High-2	H2	4
3	Low-1	L1	3
2	Assured	AF	2
1	Low-2	L2	1
0	Best Effort	BE	0

Configuration of the percentage of RSVP interface bandwidth each CT shares, for example, the Bandwidth Constraint (BC), using the class-type-bw command. The absolute value of the CT share of the interface bandwidth is derived as the percentage of the bandwidth advertised by IGP in the maximum reservable link bandwidth TE parameter, for example, the link bandwidth multiplied by the RSVP interface subscription percentage parameter. Note that this configuration also exists at the RSVP interface level and the interface specific configured value overrides the global configured value. The BC value can be changed at any time. The operator can specify the BC for a CT which is not used in any of the TE class definition but that does not get used by any LSP originating or transiting this node.
Configuration of the Admission Control Policy to be used: only the Maximum Allocation Model (MAM) is supported. The MAM value represents the bandwidth constraint models for the admission control of an LSP reservation to a link.

RSVP protocol level

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