Configuring the Ingress Router for Static LSPs

The ingress router checks the IP address in the incoming packet’s destination address field and, if it finds a match in the routing table, applies the label associated with that address to the packets. The label has forwarding information associated with it, including the address of the next-hop router, and the route preference and CoS values.

To configure static LSPs on the ingress router, include the static-path statement:

You can include this statement at the following hierarchy levels:

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

The next-hop and push statements are required; the other statements are optional.

Each static-path statement consists of the following parts:

• Criteria to use to analyze an incoming packet:

  • The inet option creates an LSP that handles IPv4 packets. All static MPLS routes created using the inet option are installed in the default IPv4 routing table (inet.0), and the creating protocol is identified as static. This process is no different from creating static IPv4 routes at the [edit routing-options static] hierarchy level.
  • In the prefix option, you configure the IP destination address to check when incoming packets are analyzed. If the address matches, the specified label, out-label, is assigned to the packet, and the packet enters an LSP. Each prefix that you specify is installed as a static route in the routing table. You can specify one or more prefix statements at the [edit protocols mpls static-path] hierarchy level.
• The next-hop statement, which supplies the IP address of the next hop to the destination. You can specify this as the IP address of the next hop, the interface name (for point-to-point interfaces only), or as address/interface-name to specify an IP address on an operational interface. When the next hop is on a directly attached interface, the route is installed in the routing table. You cannot configure a LAN or nonbroadcast multiaccess (NBMA) interface as a next-hop interface.

• Label properties applied to the packet in the LSP, which are defined by the following statements:

  • push out-label—Push one more label on top of the stack.
  • double-push bottom-label top-label—Push two more labels on top of the stack.
  • triple-push bottom-label middle-label top-label—Push three more labels on top of the stack.

    A label is a 20-bit integer, so it can be a number from 0 through 1,048,575 (220– 1). Labels 0 through 999,999 are for internal use. Labels 1,000,000 through 1,048,575 are unassigned by the JUNOS software and are available for static LSPs. When you configure static LSPs, you can use only this range of labels.

  • Preference of this route (defined by the preference preference statement).
  • CoS value to apply to the packet (defined by the class-of-service cos-value statement).

To determine whether a static ingress route is installed, use the command show route table inet.0 protocol static. The following is sample output. The push keyword identifies that a label is to be added in front of an IP packet.

10.0.0.0       *[Static/5] 00:01:48
> to 11.1.1.1 via so-0/0/0, push 1000123 

Example: Configuring the Ingress Router

Configure the ingress router for a static LSP that consists of three routers (see Figure 20).

Figure 20: Static MPLS Configuration

For packets addressed to 10.0.0.0, assign label 1000123 and transmit them to the next-hop router at 11.1.1.1:

To determine whether the static ingress route is installed, use the following command:

The following is a sample of the output. The push 1000123 keyword identifies the route.

10.0.0.0/8       *[Static/5] 00:01:48
> to 11.1.1.1 via so-0/0/0, push 1000123

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