H3C Technologies H3C S10500 Series Switches - Manual (Page 384)

369
Concepts
Policy
A policy is used to route IP packets. A policy can consist of one or multiple nodes.
Node
A node is identified by a node number. The node with the smallest node number has the highest priority.
A policy node consists of if-match and apply clauses. An if-match clause specifies a match criterion on
a node, and an apply clause specifies an action to be taken on packets.
The action to be taken on matched packets depends on the match mode, which can be permit or deny.
if-match clause
This Switch Series supports the if-match acl clause.
You can specify only one if-match clause of each type in a policy node.
apply clause
This Switch Series supports three apply clauses, apply ip-precedence, apply ip-address next-hop, and
apply ip-address default next-hop.
NOTE:
The apply ip-address default next-hop command takes effect only when no next hop is defined, or the
defined next hop is invalid and the destination address does not match any route in the routing table.
Relationship between the match mode and clauses
Table 7 Relationship between the match mode and the clauses
Then…
If a packet…
In permit mode In deny mode
Matches all the if-match clauses
on a policy node
The apply clause is executed, and
the packet will not go to the next
policy node for a match.
The apply clause is not executed, the
packets will not go to the next policy
node for a match, and will be
forwarded according to the routing
table.
Fails to match an if-match clause
on the policy node
The apply clause is not executed,
and the packet will go to the next
policy node for a match. The apply clause is not executed,
and the packet will go to the next
policy node for a match.
The nodes of a policy are in an OR relationship. If a packet matches a node, it passes the policy; if the
packet does not match any node of the policy, it fails to pass the policy and is forwarded according to
the routing table.
QoS mode
The QoS policy uses QoS traffic classification to define matching criteria, and uses the redirection action
of traffic behavior to guide packet forwarding in order to implement flexible routing.
PBR takes precedence over destination-based routing. If a packet meets the match criteria, PBR applies;
otherwise, destination-based routing applies.