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Configuring a Hierarchy of RSVP LSPs to Tunnel Multiple RSVP LSPs Over a Single RSVP LSP

The following sections describe how to configure a hierarchy of RSVP LSPs:

Configuring an RSVP LSP on Ingress Routers

Configure a standard RSVP LSP on the ingress router to be used as the forwarding adjacency LSP (see label-switched-path). This LSP requires no special configuration to function as a forwarding adjacency LSP.

Configuring Forwarding Adjacencies

A forwarding adjacency is a type of GMPLS traffic engineering link. It requires that you configure local and remote addresses to identify the link. A forwarding adjacency is associated with a specific peer router. You could configure multiple forwarding adjacencies to the same peer router.

To configure a forwarding adjacency, you need to configure the te-link statement at the [edit protocols link-management] hierarchy level:

[edit protocols link-management]

te-link te-link-name {

label-switched-path lsp-name;

local-address ip-address;

remote-address ip-address;

}

For more information on how to configure GMPLS traffic engineering links, see Configuring LMP Traffic Engineering Links.

Note: Do not configure the control channel for a forwarding adjacency peer router. Configuring a control channel causes the commit operation to fail.

The following sections describe how to configure the te-link statement for a forwarding adjacency:

Configuring the Local IP Address for Forwarding Adjacencies

To configure the local IP address for the forwarding adjacency, include the local-address statement:

local-address ip-address;

For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.

Note: If you configure local-address, you must also configure remote-address.

Configuring the Remote IP Address for Forwarding Adjacencies

The address of the peer router is the node ID for the forwarding adjacency LSP egress node. You configure this node ID for the forwarding adjacency using the remote-address statement:

remote-address ip-address;

You can include this statement at the following hierarchy levels:

[edit protocols link-management te-link te-link-name]
[edit logical-systems logical-system-name protocols link-management te-link te-link-name]

Note: If you configure remote-address, you must also configure local-address.

Configuring the LSP for Forwarding Adjacencies

To configure a router to function as a forwarding adjacency, use the label-switched-path statement and specify the LSP configured in Configuring a Hierarchy of RSVP LSPs to Tunnel Multiple RSVP LSPs Over a Single RSVP LSP:

label-switched-path label-switched-path-name;

You can include this statement at the following hierarchy levels:

[edit protocols link-management te-link te-link-name]
[edit logical-systems logical-system-name protocols link-management te-link te-link-name]

Configuring RSVP for Forwarding Adjacencies

For the forwarding adjacency to function properly, RSVP must be made aware of it. Do this by specifying the name of the peer interface corresponding to the link-management peer associated with the forwarding adjacency. Including the peer-interface statement at the [edit protocols rsvp] hierarchy level enables RSVP to use all of the traffic engineering links configured for that peer. You can also configure RSVP control-plane parameters such as the hello interval and refresh reduction.

To configure RSVP to recognize a forwarding adjacency, include the peer-interface statement:

peer-interface peer-interface-name {

disable;

(aggregate | no-aggregate);

authentication-key key;

hello-interval seconds;

(reliable | no-reliable);

}

You can include this statement at the following hierarchy levels:

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

For more information on how to configure the peer-interface statement, see Configuring RSVP and OSPF for LMP Peer Interfaces.

Advertising Forwarding Adjacencies Using OSPF

You can allow other routers to dynamically signal paths over a forwarding adjacency LSP by configuring OSPF. This configuration is optional.

If you configure OSPF to advertise a forwarding adjacency LSP, the LSP is added to the traffic engineering database on each router in the traffic engineering domain. Because the forwarding adjacency LSP is unidirectional, the corresponding traffic engineering link (forwarding adjacency) is also unidirectional. The forwarding adjacency LSP appears as a standard traffic engineering database half-link to all routers in the traffic engineering domain.

Constrained Shortest Path First (CSPF) performs a bidirectional link check to ensure that traffic can flow in both directions. CSPF checks for a reverse link, either the exact reverse forwarding adjacency or another reverse link. If there is no reverse link from the forwarding adjacency LSP egress router to the forwarding adjacency LSP ingress router, the CSPF check fails.

CSPF might find another parallel reverse link. However, the LSP cannot function properly over the forwarding adjacency unless you have explicitly configured a corresponding forwarding adjacency LSP to handle the traffic flowing in the opposite direction on the forwarding adjacency LSP egress router.

To advertise the traffic engineering properties of a forwarding adjacency to a specific peer router, include the peer-interface statement:

peer-interface peer-interface-name {

dead-interval seconds;

disable;

hello-interval seconds;

retransmit-interval seconds;

transit-delay seconds;

}

You can configure this statement at the following hierarchy levels: