H3C Technologies H3C SR8800 - Manual (Page 125)

116
Step Command Remarks
2. Associate the static route
with a track entry to
check the reachability of
the next hop.
• Approach 1:
ip route-static dest-address { mask |
mask-length } { next-hop-address | vpn-instance
d-vpn-instance-name next-hop-address } track
track-entry-number [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
• Approach 2:
ip route-static vpn-instance
s-vpn-instance-name&<1-6> dest-address { mask
| mask-length } { next-hop-address [ public ]
track track-entry-number | vpn-instance
d-vpn-instance-name next-hop-address track
track-entry-number } [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
Use either approach.
Not configured by
default.
NOTE:
•
If you associate a track entry with a nonexistent static route, the static route is automatically created.
• You can associate a track entry with a static route before or after you create the track entry. However, the
association takes effect only after you create the track entry with the track command.
• If the track module detects the next hop reachability of the static route in a private network through
NQA, the VPN instance name of the next hop of the static route must be consistent with that configured
for the NQA test group. Otherwise, the reachability detection cannot function properly.
• If a static route needs route recursion, the associated track entry must monitor the next hop of the
recursive route instead of that of the static route; otherwise, a valid route may be considered invalid.
• For more information about static route configuration, see Layer 3—IP Routing Configuration Guide.
Associating track with PBR
Policy-based routing (PBR) is a routing mechanism based on user-defined policies. Different from the
traditional destination-based routing mechanism, PBR enables you to use a policy (based on the source
address, packet length, and other criteria) to route packets. You can specify the VPN instance, packet
priority, outgoing interface, next hop, default outgoing interface, default next hop, and other parameters
to guide the forwarding of packets that match specific ACLs or have specific lengths.
PBR cannot detect the availability of any action taken on packets. When an action is not available,
packets processed by the action may be discarded. For example, configure PBR to forward packets that
match certain criteria through a specific interface. When the specified interface fails, PBR cannot sense
the failure, and continues to forward matching packets out of the interface.
This problem can be solved by associating track with PBR, which improves the flexibility of PBR
application, and enables PBR to sense topology changes.
After you associate a track entry with an apply clause, the detection module associated with the track
entry sends the detection result of the availability of the object (an interface or an IP address) specified
in the apply clause.
• The Positive state of the track entry shows that the object is available, and the apply clause is valid.
• The Negative state of the track entry shows that the object is not available, and the apply clause is
invalid.