HP HSR6800 Configuration Manual page 53

Static routing
Static routing is the easiest way to route traffic along an MPLS TE tunnel. You only need to manually
create a route that reaches the destination through the tunnel interface.
For more information about static routing, see Layer 3—IP Routing Configuration Guide.
Policy-based routing
You can also use policy-based routing to route traffic over an MPLS TE tunnel. In this method, you
create a policy that specifies the MPLS TE tunnel interface as the output interface for traffic that
matches certain criteria defined in the referenced ACL.
This policy should be applied to the incoming interface.
For more information about policy-based routing, see Layer 3—IP Routing Configuration Guide.
Automatic route advertisement
You can use automatic route advertisement to advertise MPLS TE tunnel interface routes to IGPs,
allowing traffic to be routed down MPLS TE tunnels.
Two methods are available to automatic route advertisement: IGP shortcut and forwarding
adjacency.
OSPF and IS-IS support both methods where TE tunnels are considered point-to-point links and TE
tunnel interfaces can be set as outgoing interfaces.
IGP shortcut, also known as autoroute announce, considers a TE tunnel as a logical interface
directly connected to the destination when computing IGP routes on the ingress of the TE tunnel.
IGP shortcut and forwarding adjacency are different in that in the forwarding adjacency method,
routes with TE tunnel interfaces as outgoing interfaces are advertised to neighboring devices but not
in the IGP shortcut method. Therefore, TE tunnels are visible to other devices in the forwarding
adjacencymethod but not in the IGP shortcut method.
Figure 17 IGP shortcut and forwarding adjacency
A TE tunnel is present between Router D and Router C. With IGP shortcut enabled, the ingress node
Router D can use this tunnel when calculating IGP routes. This tunnel, however, is invisible to Router
A. Therefore, Router A cannot use this tunnel to reach Router C. With forwarding adjacency enabled,
Router A can know the presence of the TE tunnel and forward traffic to Router C to Router D though
this tunnel.
The configuration of IGP shortcut and forwarding adjacency is broken down into tunnel configuration
and IGP configuration. When making tunnel configuration on a TE tunnel interface, consider the
following:
•
The tunnel destination address must be in the same area where the tunnel interface is located.
•
The tunnel destination address must be reachable through intra-area routing.
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