H3C Technologies H3C S12500-X Series Switches - Manual (Page 84)

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Configuring a static CRLSP
Overview
A static Constraint-based Routed Label Switched Path (CRLSP) is established by manually specifying the
incoming label, outgoing label, and required bandwidth on each node (ingress, transit, or egress node)
of the forwarding path. If the device does not have enough bandwidth resources required by a CRLSP,
the CRLSP cannot be established.
Static CRLSPs consume fewer resources, but they cannot automatically adapt to network topology
changes. Therefore, static CRLSPs are suitable for small and stable networks with simple topologies.
Follow these guidelines to establish a static CRLSP:
• On the ingress node, specify the outgoing label for the CRLSP, the next hop or the outgoing
interface to the next hop, and the required bandwidth, create an MPLS TE tunnel interface, and
reference the static CRLSP for the tunnel interface. The tunnel interface adds the outgoing label of
the static CRLSP to each packet, and forwards the packet to the next hop or out of the outgoing
interface.
• A transit node swaps the label carried in a received packet with a specific label, and forwards the
packet to the next hop or out of the outgoing interface. You must specify the incoming label, the
outgoing label, the next hop or the outgoing interface, and the required bandwidth on each transit
node.
• If it is not configured with the penultimate hop popping function, an egress node pops the incoming
label of a packet, and performs label forwarding according to the inner label or IP forwarding. You
are only required to specify the incoming label on the egress node.
• The outgoing label specified on an LSR must be the same as the incoming label specified on the
directly connected downstream LSR.
Configuration procedure
Static CRLSPs are special static LSPs. They use the same label space as static LSPs. On a device, a static
CRLSP and a static LSP cannot use the same incoming label.
A static CRLSP can be used to forward MPLS TE traffic only after you create an MPLS TE tunnel interface
on the ingress node and reference the static CRLSP for the tunnel interface. For more information about
MPLS TE, see "Configuring MPLS TE."
Before you configure a static CRLSP, complete the following tasks:
• Identify the ingress node, transit nodes, and egress node of the CRLSP.
• Enable MPLS on all interfaces that participate in MPLS forwarding. For more information, see
"Configuring basic MPLS."
• Enable MPLS TE for each node and interface that the CRLSP traverses. For more information, see
"Configuring MPLS TE."
To configure a static CRLSP: