RSVP-TE Configuration Example

RSVP-TE LSPs comprise profiles, paths, and the actual LSP. This section describes how to configure an RSVP-TE LSP.

Configuring RSVP LSPs is a multi-step process with some optional steps, depending on the specific requirements of the LSP. Conceptually, a number of mandatory elements must be configured to create an RSVP-TE LSP. In addition, you can also configure optional elements. In certain configurations, there are also order dependencies.

The profile contains constraints that you might wish to apply to the LSP. These constraints can affect the path selected across the MPLS domain in order to meet those constraints. Examples of profile parameters include bandwidth, setup, and hold priority relative to other configured LSPs.

The path can be used to specify the explicit path across the MPLS domain that the LSP should follow. This is done using EROs. An ERO is an object, sent as part of the LSP setup request (path message) that explicitly specifies the part of the path across the MPLS domain the setup request should follow. You can configure both loose and strict EROs in a path.

Certain elements of configuration are order dependent. For example if you specify a profile or path when creating an LSP, those path or profile definitions must already exist. Similarly a path must exist before an ERO is created, as the ERO is added explicitly to the path.

The typical steps used to configure and verify an RSVP-TE LSP are as follows:

  1. Create and configure a path (optional).
  2. Reserve bandwidth for the LSP (optional).
  3. Create and configure a profile (optional).
  4. Create an LSP (mandatory).
  5. Add a primary/secondary path to the LSP (mandatory).
  6. Add a secondary path to the LSP (optional).
  7. Verify LSP status (recommended).
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    RSVP-TE Configuration Example
    ../Graphics/MPLS_24.svg

    The configuration example, shown in the following figure, creates primary and secondary LSPs between the node Glasgow and the node Birmingham. The steps specifically create an LSP between Glasgow and Birmingham based on an explicitly routed path via London with bandwidth, setup priority, and hold priority profile requirements. A secondary path is also created which, in the event of failure of a link or node on the primary path, activates the secondary LSP from Glasgow to Liverpool to Birmingham.

    Note

    Note

    Before configuring RSVP-TE LSPs, you need to enable the protocol on the switch, and an initial step of adding RSVP-TE to a VLAN must be carried out for all VLANs over which the user wishes RSVP-TE LSPs to be signaled. This is a one-time operation.

    A loopback VLAN with the LSR-ID should be added to MPLS to allow RSVP-TE LSPs to be established to the LSR-ID.

    The following commands configure RSVP-TE for the switch and add RSVP signaling capabilities to the specified VLANs:

    enable mpls
    enable mpls protocol rsvp-te
    configure mpls add vlan loopback
    configure mpls add vlan gla-lon
    enable mpls rsvp-te vlan gla-lon
    enable mpls vlan gla-lon
    configure mpls add vlan gla-liv
    enable mpls rsvp-te vlan gla-liv
    enable mpls vlan gla-liv

    The following commands reserve bandwidth for RSVP-TE LSPs on these MPLS interfaces:

    configure mpls rsvp-te bandwidth committed-rate 20 Mbps gla-lon
    configure mpls rsvp-te bandwidth committed-rate 20 Mbps gla-liv

    The following commands create and configure an LSP profile named Glasgow-Birmingham-pro.

    LSPs that use the Glasgow-Birmingham-pro profile are signaled with a reserved bandwidth of 10 Mbps and an LSP setup and hold priority of 5.

    create mpls rsvp-te profile Glasgow-Birmingham-pro
    configure mpls rsvp-te profile Glasgow-Birmingham-pro bandwidth committed-rate 10 m
    configure mpls rsvp-te profile Glasgow-Birmingham-pro setup-priority 5 hold-priority 5

    The following commands define the primary and secondary paths between Glasgow and Birmingham:

    create mpls rsvp-te path Glasgow-Birmingham-pri-path
    create mpls rsvp-te path Glasgow-Birmingham-sec-path

    The following commands pin each path to an LSR, such that each path takes a different route to the endpoint 4.0.0.0.

    Path Glasgow-Birmingham-pri-path is routed through LSR 1.0.0.0 and path Glasgow-Birmingham-sec-path is routed through LSR 5.0.0.0.

    configure mpls rsvp-te path Glasgow-Birmingham-pri-path add ero 1.0.0.0/32 loose
    configure mpls rsvp-te path Glasgow-Birmingham-sec-path add ero 5.0.0.0/32 loose

    The following commands create one RSVP-TE LSP with one primary and one secondary or backup path.

    Each path uses the same profile.

    create mpls rsvp-te lsp Glasgow-Birmingham-lsp destination 4.0.0.0
    configure mpls rsvp lsp Glasgow-Birmingham-lsp add path Glasgow-Birmingham-pri-path profile Glasgow-Birmingham-pro primary
    configure mpls rsvp lsp Glasgow-Birmingham-lsp add path Glasgow-Birmingham-sec-path profile Glasgow-Birmingham-pro secondary
    
    Note

    Note

    The secondary LSP is signaled, however it remains in a standby state unless the primary path becomes unavailable.

    By default, a VPLS pseudowire flows over any available LSP.

    However, a VPLS pseudowire can be specifically directed to use a configured RSVP-TE based LSP. Configuration is no different from configuring an LDP-based VPLS pseudowire, except that the RSVP-TE LSP is explicitly specified. The following command specifically directs a VPLS pseudowire to use a previously configured RSVP-TE LSP:

    configure vpls Glasgow-Birmingham-cust1 peer 4.0.0.0 add mpls lsp Glasgow-Birmingham-lsp