Traffic Forwarding - HP FlexNetwork 10500 Series Configuration Manual

4. PCE 1 uses the local and received path information to select an end-to-end path for the PCC to
reach the CRLSP destination, and sends the path to PCC as a reply.
5. PCC uses the path calculated by PCEs to establish the CRLSP through RSVP-TE.
Figure 25 BRPC path calculation
Area 1
PCC

Traffic forwarding

After an MPLS TE tunnel is established, traffic is not forwarded on the tunnel automatically. You must
direct the traffic to the tunnel by using one of the following methods:
Static routing
You can direct traffic to an MPLS TE tunnel by creating a static route that reaches the destination
through the tunnel interface. This is the easiest way to implement MPLS TE tunnel forwarding. When
traffic to multiple networks is to be forwarded through the MPLS TE tunnel, you must configure
multiple static routes, which are complicated to configure and difficult to maintain.
For more information about static routing, see Layer 3—IP Routing Configuration Guide.
Automatic route advertisement
You can also configure automatic route advertisement to forward traffic through an MPLS TE tunnel.
Automatic route advertisement distributes the MPLS TE tunnel to the IGP (OSPF or IS-IS), so the
MPLS TE tunnel can participate in IGP routing calculation. Automatic route advertisement is easy to
configure and maintain.
Automatic route advertisement can be implemented by using the following methods:
•
IGP shortcut—Also known as AutoRoute Announce. It considers the MPLS TE tunnel as a link
that directly connects the tunnel ingress node and the egress node. Only the ingress node uses
the MPLS TE tunnel during IGP route calculation.
•
Forwarding adjacency—Considers the MPLS TE tunnel as a link that directly connects the
tunnel ingress node and the egress node, and advertises the link to the network through an IGP.
Every node in the network uses the MPLS TE tunnel during IGP route calculation.
As shown in
only the ingress node Router D to use the MPLS TE tunnel in the IGP route calculation. Router A
cannot use this tunnel to reach Router C. With forwarding adjacency enabled, Router A can learn this
MPLS TE tunnel and transfer traffic to Router C by forwarding the traffic to Router D.
Area 0
PCE 1
Path calculation request
Path calculation reply
Calculated path
Figure 26, an MPLS TE tunnel exists from Router D to Router C. IGP shortcut enables
PCE 2
Area 2
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