Discussion

the community string from the route, no action is taken and evaluation automatically
continues with the send-statics policy, which has an accept action to terminate policy
evaluation.
When chaining policies together in this way, make sure that the last policy in the
chain has a terminating action (either then accept or then reject). One trick for
ensuring that there’s always a terminating action is to create a policy that is nothing
more than the action itself and place it at the end of the chain:
[edit policy-options policy-statement final-accept]
aviva@router1# set then accept
[edit protocols bgp group external-group]
aviva@router1# set export [ block-private remove-communities send-statics finalaccept
]
You would no longer need the set then accept command at the end of the sendstatics
policy, so the configured policies would look like this:
[edit]
aviva@router1> show configuration policy-options
policy-statement remove-communities {
term 1 {
then {
community delete all-communities;
}
}
}
policy-statement send-statics {
term 1 {
from protocol [ static direct ];
}
}
policy-statement final-accept {
term 1 {
then accept;
}
}
community all-communities members *:*;
The second configuration in this recipe chains policies using the next policy action
in a then clause. This forces policy evaluation to continue with the next policy after a
match occurs. The next policy action is optional because it is the default action that
the policy evaluation takes when a match occurs; when you do not include an
accept, reject, ornext term action; and when there are no more terms in the routing
policy. However, using it can speed up policy evaluation when a policy contains several
terms and the import or export command references a number of policies.
It is also possible to explicitly jump to the next term in a policy when a match
occurs:
[edit policy-options policy-statement from-my-customers]
aviva@router1# set term 1 from protocol direct
aviva@router1# set term 1 then local-preference 300
aviva@router1# set term 1 then community set 65500:12345
Creating a Chain of Routing Policies | 299
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