H3C Technologies H3C S10500 Series Switches - Manual (Page 104)

93
The RSVP-TE GR function depends on the extended hello capability of RSVP-TE. A GR-capable device
advertises its GR capability and relevant time parameters to its neighbors by extended RSVP hello
packets. If a device and all its neighbors have the RSVP GR capability and have exchanged GR
parameters, each of them can function as the GR helper of another device, allowing data to be
forwarded without interruption when the GR restarter is rebooting.
A GR helper considers that a GR restarter is rebooting when it receives no Hello packets from the
restarter in a specified period of time. When a GR restarter is rebooting, the GR helpers retain soft state
information about the GR restarter and keep sending Hello packets periodically to the GR restarter until
the restart timer expires.
If a GR helper and the GR restarter reestablish a Hello session before the restart timer expires, the
recovery timer is started and signaling packet exchanging is triggered to restore the original soft state.
Otherwise, all RSVP soft state information and forwarding entries relevant to the neighbor are removed.
If the recovery timer expires, soft state information and forwarding entries that are not restored during the
GR restarting process are removed.
NOTE:
After enabled with RSVP-TE GR, the switch can act as a GR restarter and a GR helper simultaneously.
Traffic forwarding
For traffic to travel along an LSP tunnel, you must make configuration after creating the MPLS TE tunnel.
Otherwise, traffic is IP routed.
Even when an MPLS TE tunnel is available, traffic is IP routed if you do not configure it to travel the tunnel.
For traffic to be routed along an MPLS TE tunnel, you can use static routing, policy routing, or automatic
route advertisement.
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.
NOTE:
For more information about static routing, see Layer 3—IP Routing Configuration Guide.
Policy routing
You can also use policy routing to route traffic over an MPLS TE tunnel. In this approach, you need to
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.
NOTE:
For more information about policy 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.