H3C Technologies H3C S12500 Series Switches - Manual (Page 217)

206
Step Command Remarks
2. Associate the static route
with a track entry to
check the reachability of
the next hop.
• Method 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 ]
• Method 2:
ip route-static vpn-instance
s-vpn-instance-name&<1-6> dest-address { mask
| mask-length } { next-hop-address track
track-entry-number [ public ] | vpn-instance
d-vpn-instance-name next-hop-address track
track-entry-number } [ preference
preference-value ] [ tag tag-value ] [ description
description-text ]
Use either command.
Not configured by
default.
For more information
about static route
configuration, see
Layer 3—IP Routing
Configuration Guide.
NOTE:
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.
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, next hop,
and other parameters to guide the forwarding of packets that match specific ACLs.
PBR cannot detect the availability of any action taken on packets. When an action is not available,
packets processed by the action might be discarded. For example, configure PBR to forward packets that
match certain criteria through a specific next hop. When the next hop fails, PBR cannot sense the failure,
and continues to forward matching packets through the next hop.
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.
• The Invalid state of the track entry shows that the apply clause is valid.
The object that can be associated with a track entry is next hop.
Configuration prerequisites
Before you associate Track with PBR, create a policy or a policy node and configure the match criteria as
well.