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Creating a Named Path

To configure signaled LSPs, you must first create one or more named paths on the ingress router. For each path, you can specify some or all transit routers in the path, or you can leave it empty.

Each pathname can contain up to 32 characters and can include letters, digits, periods, and hyphens. The name must be unique within the ingress router. Once a named path is created, you can use the named path with the primary or secondary statement to configure LSPs at the [edit protocols mpls label-switched-path label-path-name] hierarchy level. You can specify the same named path on any number of LSPs.

To determine whether an LSP is associated with the primary or secondary path in an RSVP session, issue the show rsvp session detail command. For more information, see the JUNOS Routing Protocols and Policies Command Reference.

To create an empty path, create a named path by including the following form of the path statement. This form of the path statement is empty, which means that any path between the ingress and egress routers is accepted. In actuality, the path used tends to be the same path as is followed by destination-based, best-effort traffic.




path path-name;

You can include this statement at the following hierarchy levels:

[edit protocols mpls]
[edit logical-systems logical-system-name protocols mpls]

To create a path in which you specify some or all transit routers in the path, include the following form of the path statement, specifying one address for each transit router:




path path-name {

address | hostname <strict | loose>;
}

You can include this statement at the following hierarchy levels:

[edit protocols mpls]
[edit logical-systems logical-system-name protocols mpls]

In this form of the path statement, you specify one or more transit router addresses. Specifying the ingress and/or egress routers is optional. You can specify the address or hostname of each transit router, although you do not need to list each transit router if its type is loose. Specify the addresses in order, starting with the ingress router (optional) or the first transit router, and continuing sequentially along the path up to the egress router (optional) or the router immediately before the egress router. You need to specify only one address per router hop. If you specify more than one address for the same router, only the first address is used; the additional addresses are ignored and truncated.

For each router address, you specify the type, which can be one of the following:

strict—(Default) The route taken from the previous router to this router is a direct path and cannot include any other routers. If address is an interface address, this router also ensures that the incoming interface is the one specified. Ensuring that the incoming interface is the one specified is important when there are parallel links between the previous router and this router. It also ensures that routing can be enforced on a per-link basis.
For strict addresses, you must ensure that the router immediately preceding the router you are configuring has a direct connection to that router. The address can be a loopback interface address, in which case the incoming interface is not checked.
loose—The route taken from the previous router to this router need not be a direct path, can include other routers, and can be received on any interface. The address can be any interface address or the address of the loopback interface.

Examples: Creating a Named Path

The following path, to-hastings, specifies the complete strict path from the ingress to the egress routers through 14.1.1.1, 13.1.1.1, 12.1.1.1, and 11.1.1.1, in that order. There cannot be any intermediate routers except the ones specified. However, there can be intermediate routers between 11.1.1.1 and the egress router because the egress router is not specifically listed in the path statement. To prevent intermediate routers before egress, configure the egress router as the last router, with a strict type.



[edit protocols mpls]
path to-hastings {
14.1.1.1 strict;
13.1.1.1 strict;
12.1.1.1 strict;
11.1.1.1 strict;
}

The following path, alt-hastings, allows any number of intermediate routers between routers 14.1.1.1 and 11.1.1.1. In addition, intermediate routers are permitted between 11.1.1.1 and the egress router.



[edit protocols mpls]
path alt-hastings {
14.1.1.1 strict;
11.1.1.1 loose;
}

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